Author Topic: Basic Power Supply  (Read 8342 times)

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Offline psysc0rpi0n

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Basic Power Supply
« on: July 27, 2019, 01:33:16 pm »
Hello.

I'm seeking advice.
I want to purchase a basic power supply for home and/or hobby usage.
Not many features needed, just the basic for security like over current protection (maybe not the correct wording. Is it reverse current?).

I probably won't need more than 30V and maybe up to 10A (5A would also be OK I guess).

I think 2 channels is almost mandatory to have the possibility of having access to mirrored voltages!

What brands would you suggest up to about 150€???
 

Offline Jan Audio

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Re: Basic Power Supply
« Reply #1 on: July 27, 2019, 01:39:56 pm »
If that exist i buy also.
You need more money.
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #2 on: July 27, 2019, 02:09:06 pm »
What can I get up to that price?


Edited;

I have no clue about brands but looks like that with less than 250€ I won't get anything with 2 channels. Disregarding the price, what are low budget options with 2 ch?

Global Specialties brand is anything good?

I found this LeCroy but it's almost 500€...
Link Lecroy Teledyne T3PS23203
« Last Edit: July 27, 2019, 02:23:57 pm by psysc0rpi0n »
 

Offline Jan Audio

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Re: Basic Power Supply
« Reply #3 on: July 27, 2019, 02:33:12 pm »
There are 3 channel PSUs for around 300 Siglent SPD3303C only i dont want that brand.
I like the iTech 6302 for around 500, only its still chinese crap.
Better bring 1400 euro for some quality rhode & schwartz, they just increased the prices from 1250 to 1400, now i can not afford that even more ( not that NGE crap model ).

I see there is a UNI-T UTP3303C also, i would not buy that brand.
« Last Edit: July 27, 2019, 02:36:03 pm by Jan Audio »
 


Offline Candid

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Re: Basic Power Supply
« Reply #5 on: July 27, 2019, 03:39:44 pm »
1. https://www.welectron.com/Korad-KD3305D-Labornetzteil_1
2. https://www.welectron.com/Korad-KA3305P-Benchtop-Power-Supply

1. 179,- EUR including 19% VAT
2. 229,- EUR including 19% VAT

Shipping from Germany to Portugal about 10 EUR only with DHL

No. 2 I can suggest, it works very well for the price. No. 1 may be very similar in quality.
« Last Edit: July 27, 2019, 03:44:17 pm by Candid »
 

Offline Jan Audio

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Re: Basic Power Supply
« Reply #6 on: July 27, 2019, 03:42:08 pm »
Remember this : if your PSU fails, they keep sending it back to china until you have no more warranty,
the same counts for the R&S brand ( not to china then ), they dont fail as often.
With these prices it is expensive gambling.

Peaktech looks nice, it is not trusty, even before warranty ends.
No real quality control they told me in this forum.
 

Offline Candid

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Re: Basic Power Supply
« Reply #7 on: July 27, 2019, 03:47:29 pm »
I got a Korad from Welectron and it was faulty and I got it replaced without any costs for me even no postage costs for sending the faulty unit back to them. I got a DHL returning ticket sent from Welectron. Perfect service and good prices.
 

Offline Jan Audio

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Re: Basic Power Supply
« Reply #8 on: July 27, 2019, 03:52:59 pm »
Ah that is better if you get a new fresh model without repairs, if a shop can guarantee that to me i certainly buy any brand from them.
New model with new guarantee that is.
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #9 on: July 27, 2019, 04:01:49 pm »
There are 3 channel PSUs for around 300 Siglent SPD3303C only i dont want that brand.
I like the iTech 6302 for around 500, only its still chinese crap.
Better bring 1400 euro for some quality rhode & schwartz, they just increased the prices from 1250 to 1400, now i can not afford that even more ( not that NGE crap model ).

I see there is a UNI-T UTP3303C also, i would not buy that brand.

OOhhh no way. That would cost more than my Scope...
If I buy a better power supply, it will be at most 500€. And it cannot be right now. I need to wait to get my hands on that money!
 

Offline bob91343

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Re: Basic Power Supply
« Reply #10 on: July 27, 2019, 04:03:01 pm »
I have lots of power supplies, none of which I purchased new.  Swap meets, auctions, friends, all have helped stock my laboratory.  Not to mention the learning factor in trying to repair a unit that didn't do what it was intended.

I just bought a power supply at a swap meet for $2.  It had a shorted diode across the output.  It works great now, up to 18V at 2A with digital meters and current limiting.

The guy who sold it to me predicted that I would have it working in 5 minutes.  He was wrong; it took 15 minutes because it had two problems.  The other one was that the binding posts had been interchanged so it put out reverse voltage if you believed the colors.
 


Offline Jan Audio

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Re: Basic Power Supply
« Reply #12 on: July 27, 2019, 04:07:55 pm »
That velleman dont even has a type number, how can youtube find it then ?,
if its not on youtube from a user i dont like buying at all.

Owon oscilloscopes also looks nice, only no one on youtube has it, must have a reason maybe because no one has one.
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #13 on: July 27, 2019, 05:45:00 pm »
That velleman dont even has a type number, how can youtube find it then ?,
if its not on youtube from a user i dont like buying at all.

Owon oscilloscopes also looks nice, only no one on youtube has it, must have a reason maybe because no one has one.

Well, I'm not looking for scopes. That's was just a comment on the price you told me for a good Power Supply. Not even my scope cost that much. And it's a cheap one too but it fits my needs so far. It's a basic Rigol MSO1104Z.

So to buy a Power Supply that costs more than a scope it's not reasonable for me not even in my possibilities. I can't afford such a power supply. I may consider something around those 400€ or 500€ max but not right now! I need to save some more to be able to purchase such power supply!
 

Offline Nornand

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Re: Basic Power Supply
« Reply #14 on: July 27, 2019, 05:45:16 pm »
That velleman dont even has a type number, how can youtube find it then ?,


LABPS23023
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #15 on: July 27, 2019, 06:43:57 pm »
That velleman dont even has a type number, how can youtube find it then ?,


LABPS23023

Can't find reviews, tests or anything relevant about that brand!
 

Offline ledtester

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Re: Basic Power Supply
« Reply #16 on: July 27, 2019, 07:29:31 pm »
A couple of years ago I got a Tenma 72-8335A which has 2 channels @ 24V 1A/CH plus a 5V/2A channel, and it continues to serve me very well. Since then I've acquired a used Topward 6303A which is more in line with what you are considering. However, I still find that my Tenma is often adequate for the testing that I need to do.

Most digital and op-amp circuits can get by on 24V / 1A. There will be times when you need more volts or amps, but I've always been able to cobble together another power supply to do the job. Step-down converters like the Ruideng offerings make this easy and offer very good performance.

I got my Tenma for around $80 on sale from Newark. It's not available from the major distributors anymore, but I found this link selling used ones - and they have a European phone number:

(link)

The main point I wanted to make, though, is that you might be able to get by with multiple cheaper supplies.

And here's Dave's review of an earlier model Ruideng buck-converter module - the newer ones have a nicer user interface:

https://youtu.be/Cw2AjcczHg4

« Last Edit: July 27, 2019, 07:32:37 pm by ledtester »
 

Online tautech

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Re: Basic Power Supply
« Reply #17 on: July 27, 2019, 08:26:26 pm »
There are 3 channel PSUs for around 300 Siglent SPD3303C only i dont want that brand.
I like the iTech 6302 for around 500, only its still chinese crap.
Better bring 1400 euro for some quality rhode & schwartz, they just increased the prices from 1250 to 1400, now i can not afford that even more ( not that NGE crap model ).

I see there is a UNI-T UTP3303C also, i would not buy that brand.

OOhhh no way. That would cost more than my Scope...
If I buy a better power supply, it will be at most 500€. And it cannot be right now. I need to wait to get my hands on that money!
370 Euro buys you a good 3ch PSU with the ability to parallel to 30V @ 6A and series for 60V @ 3A.
They don't give issues and are a steady good seller here.
https://www.siglenteu.com/power-supplies/spd3303x-spd3303x-e-series-programmable-dc-power-supply/
Avid Rabid Hobbyist
 
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Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #18 on: July 27, 2019, 10:17:16 pm »
There are 3 channel PSUs for around 300 Siglent SPD3303C only i dont want that brand.
I like the iTech 6302 for around 500, only its still chinese crap.
Better bring 1400 euro for some quality rhode & schwartz, they just increased the prices from 1250 to 1400, now i can not afford that even more ( not that NGE crap model ).

I see there is a UNI-T UTP3303C also, i would not buy that brand.

OOhhh no way. That would cost more than my Scope...
If I buy a better power supply, it will be at most 500€. And it cannot be right now. I need to wait to get my hands on that money!
370 Euro buys you a good 3ch PSU with the ability to parallel to 30V @ 6A and series for 60V @ 3A.
They don't give issues and are a steady good seller here.
https://www.siglenteu.com/power-supplies/spd3303x-spd3303x-e-series-programmable-dc-power-supply/

I like that one way more despite the fact that I didn't need the fancy screen. That might be a good option.

thanks for this suggestion.

Edited;

Ohhh, I just noticed you're a Siglent ditributor, right?
 

Online nctnico

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Re: Basic Power Supply
« Reply #19 on: July 27, 2019, 10:43:04 pm »
Tautech is a Siglent distributor so according to him Siglent is always the best. Too bad he removed the line saying he is a Siglent distributor from his signature. In the 300 to 400 euro ballpark there is a lot of choice from many brands. I setup this URL to show PSUs up to about 500 euro:
https://eleshop.eu/test-measure/power-supplies/filter/price/28-517.html

I have no affiliation with this webshop other than being a customer. They carry a wide variety of brands to cater to any budget and requirement.

BTW: did you look on Ebay or your localised online advertisements website for a used power supply?
« Last Edit: July 27, 2019, 10:52:03 pm by nctnico »
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Online aristarchus

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Re: Basic Power Supply
« Reply #20 on: July 27, 2019, 11:03:30 pm »
Since seen that you also got the MSO1104z like me, my advice is to get the DP832, I got it and am happy with it two years now.
 

Online tautech

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Re: Basic Power Supply
« Reply #21 on: July 28, 2019, 02:12:32 am »
Ohhh, I just noticed you're a Siglent ditributor, right?
Yep as noted in my profile.

If I thought the X/X-E model PSU's were a POS I wouldn't suggest one as they continue to sell steadily here.
I don't have any issues with them other than with the EU and US websites that still don't show the default display like you can see here on the factory website:
http://www.siglent.com/ENs/pdxx.aspx?id=1132&T=2&tid=17

At the end of the day it's your $/Euro to spend on what best fits your needs and budget.
Good luck with your hunt.
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Online TurboTom

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Re: Basic Power Supply
« Reply #22 on: July 28, 2019, 07:51:40 am »
Since seen that you also got the MSO1104z like me, my advice is to get the DP832, I got it and am happy with it two years now.

100% confirm! AFAIK, the DP800 is the only lab supply family available in this price range with the option to enter the settings via a decimal keypad or via the encoder -- it's your choice. Having got other PSUs with encoder / pot only "programming" interface, I always prefer my DP832 or 811. Their base models can be hacked to the full-featured "A" versions. Don't let you talk out of the 832 due to the fact that CH2 and CH3 share a common ground. This has been covered in many contributions and you can use the two main channels in series, in parallel and also to provide a split, symmetric supply. The supply provides the same "headroom" as the Siglent SPD3303X series (2x 32V@3.2A max; 1x 5.3V@3.2A max), Rigol only don't promote it as a feature (maybe they should...).

Consider this: you may not need a 'scope for every single design you build or device you test, but you very likely need a PSU for it so I wouldn't skimp on that one. It may hurt a little more when buying, but later on, you will always enjoy a quality tool.

So my recommendation would be, if you are really sure you don't want a PSU with a decimal keypad, get the Siglent or a second hand "premier" brand PSU (though the second hand market in Europe isn't comparable with the US, it's much more difficult to get a good deal), otherwise get a DP832.

Cheers,
Tom
 

Online nctnico

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Re: Basic Power Supply
« Reply #23 on: July 28, 2019, 08:19:39 am »
I second the keypad suggestion on a digitally controlled PSU. I have a few of these (from HP/Agilent/Keysight) and I always use the keypad to enter the values. Much quicker than turning an encoder knob for an eternity. On an analog PSU I prefer 10 turn potmeters.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Jan Audio

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Re: Basic Power Supply
« Reply #24 on: July 28, 2019, 01:18:14 pm »
Ohhh, I just noticed you're a Siglent ditributor, right?

That is why i dont buy that brand.
 

Offline BillB

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Re: Basic Power Supply
« Reply #25 on: July 28, 2019, 03:21:21 pm »
Ohhh, I just noticed you're a Siglent ditributor, right?

That is why i dont buy that brand.

Seriously?  Because a distributor recommends the products he sells?

IIRC, tautech has never hidden the fact that he is a Siglent distributor.  It is clearly visible in his profile that can be seen on every single one of his posts.

I'll admit that I have a lot of Siglent gear, and I'm actually thankful to have an active forum member who also represents the brand.  He has provided extremely helpful support for the equipment that I have, but he also contributes extensively in general.  There are many other factory reps here for other brands that chime in occasionally to support/recommend their product and that is it.  Between the two, I'll take the active contributor.

Back to the topic at hand, I've got a few of the SPD-3303X-E's and I haven't had any problems with them.  Sure there are a few things I don't like, such as the lack of a keypad and the anemic third channel.  But, for the price, I think it offers a nice set of features for the money.     
 
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Offline Jan Audio

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Re: Basic Power Supply
« Reply #26 on: July 28, 2019, 03:42:44 pm »
I,m not here to read advertiesements.
If you get direct help in your problem topics is a good thing.

They advising only 1 brand for years, i bet people fall for it.
 

Offline Candid

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Re: Basic Power Supply
« Reply #27 on: July 28, 2019, 03:51:43 pm »
370 Euro buys you a good 3ch PSU with the ability to parallel to 30V @ 6A and series for 60V @ 3A.
They don't give issues and are a steady good seller here.
Very similar to the Korad KA3305P (Programmable benchtop power supply, 3 channels (2x30V/5A, 5V/3A), parallel and serial mode for the 2 30V/5A outputs, 315W total power, 10mV/1mA resolution, USB/RS232 interface) 229,- EUR incl. 19% VAT. THe siglent has a smarter display if needed/preferred and my have better internal electronics. The Korad has better resolution 10mV/1mA.

https://www.welectron.com/Korad-KA3305P-Benchtop-Power-Supply
« Last Edit: July 28, 2019, 03:54:03 pm by Candid »
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #28 on: July 28, 2019, 04:19:11 pm »
I've been reading posts. It is obvious and I can't see anything wrong with that, that someone representing a brand, that recommends the brand he represents.

So, I'm not paying much attention to those parts os posts that are bringing someone down just for recommending a product they represent. That's not a reason that makes a brand better or worse. Probably, way more important than the brand, is the components used inside the product.

So, I'm thankful I got here at least 3 options. Siglent, Rigol and Korad.

BTW, my multimeter was bought on that electroshop, iirc. It's polish shop, right?

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Offline Hans578

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Re: Basic Power Supply
« Reply #29 on: July 28, 2019, 04:49:59 pm »
I would buy just 2x Peaktech 6225A. Very decent power supplies imo. Doesnt take much room either since they are switching ones. From Reichelt one costs 75 euros so 2x will be excatly 150 euros. They will send all sorts of heavier stuff up to 10kg for 10 euros only all over the Europe.
 

Online nctnico

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Re: Basic Power Supply
« Reply #30 on: July 28, 2019, 05:50:54 pm »
BTW, my multimeter was bought on that electroshop, iirc. It's polish shop, right?
Eleshop.eu is a web shop from the Netherlands.

I would buy just 2x Peaktech 6225A. Very decent power supplies imo. Doesnt take much room either since they are switching ones. From Reichelt one costs 75 euros so 2x will be excatly 150 euros. They will send all sorts of heavier stuff up to 10kg for 10 euros only all over the Europe.
I strongly recommend against using a switching PSU for developing circuits. There is too much (electric) noise coming from these power supplies making it impossible to measure small signals. Switching power supplies are great if you need a lot of power and don't have to care about ripple and noise so much.
« Last Edit: July 28, 2019, 05:53:25 pm by nctnico »
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline ledtester

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Re: Basic Power Supply
« Reply #31 on: July 28, 2019, 06:29:44 pm »
So, I'm thankful I got here at least 3 options. Siglent, Rigol and Korad.

Since you're considering the Rigol and Korad offerings, you may be interested in this comparison video...

https://youtu.be/EpIxw90Oku8
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #32 on: July 28, 2019, 07:14:37 pm »
Thanks for the video.

About the shop, that name rings a bell. I bought my multimeter from a Polish shop. Can't remember the name. They had nice prices.

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Online tautech

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Re: Basic Power Supply
« Reply #33 on: July 29, 2019, 02:44:14 am »
Back to the topic at hand, I've got a few of the SPD-3303X-E's and I haven't had any problems with them.  Sure there are a few things I don't like, such as the lack of a keypad and the anemic third channel.  But, for the price, I think it offers a nice set of features for the money.     
I was never fan of that ^ either however the last week or so has me using a single channel SPD1305X for old LA battery recovery where I'm ofen checking current draw and voltages so to keep the battery cool.
When recovering old neglected batteries current draw can change dramatically and while I could set CC charging it doesn't give the same picture about what's going on so I might make adjustments a few times/day.

Despite the lack of a numeric keypad on Siglent PSU's the UI controls are quite adequate by using the Fine control to toggle to the digit you need to adjust and the </> to select the field for adjustment.
Encoder operation permits say *.1 to be reduced to *.0 and then to *-1.9 and the same for any decimal selected.

So while the lack of a numeric keypad might be seen by some as a hindrance to operation I don't feel it is as adjustments can still be made speedily with just the encoder, Fine and </> controls.
In this case Siglent's compact single channel PSU's don't have the front panel real estate for a numeric keypad and an encoder so the choice to reuse the same control layout of their 3ch PSU's makes some sense to me.

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Online nctnico

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Re: Basic Power Supply
« Reply #34 on: July 29, 2019, 09:43:23 am »
Sure you can make do with an encoder knob but a numeric keypad just is better. If you can buy a PSU with a numeric keypad for the same money, then buy that.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline BillB

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Re: Basic Power Supply
« Reply #35 on: July 29, 2019, 12:58:32 pm »
Sure you can make do with an encoder knob but a numeric keypad just is better. If you can buy a PSU with a numeric keypad for the same money, then buy that.

Similar money, but the DP800 is a tad larger too.  For me, when I was first comparing I was outfitting a very small bench and space was a premium.  I traded the keypad for the (IIRC) a larger display and the smaller size.  Frankly, the majority of the time I use them it is set and forget.  If I'm really actively hunting for precise values, I'm automating anyway.       

SPD3303X: 225(W)×143(H)×278(D) mm

DP800: 239mm(W) x 157mm(H) x 418mm(D)
 

Online TurboTom

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Re: Basic Power Supply
« Reply #36 on: July 29, 2019, 06:28:48 pm »
I guess I've got to take up the cudgels for the DP800 once again...
Besides the presence of the decimal keypad, there are two more things that I really like a lot about these PSUs: The rubber bumpers, especially those at the back, make it possible to operate the PSU resting on its rear face and to place it next to you on the floor. I found that VERY useful in several situations already. They also permit to set down the instrument on any face except the front (the terminals project).
My second "thumbs up" is the general build quality -- it's literally made like a tank. Siglent also appears to be decent qualiy but definitely not as rigid as the DP800. Korad or Owon and the likes with these flimsy reinforcement straps screwed directly to a tiny tab of the plastic front panel, making the latter a structural component of the (quite heavy) PSU, is something that I wouldn't consider adequate. But of course, electrically these power supplies may also do a good job.
Regarding the Rigol DP800 family, nowadays the issues of the early revisions that Dave highlighted, have been completely solved.
Price-wise, if you're prepared to spend 400 euros, I think some 70 or 80 more to get a more decent unit, shouldn't make much difference. If, on the other hand, your "comfort zone" stretches up to 250 euros, the only options will be the "cheapos". Depending on your application(s), you may even get along fine with a switcher, but if you only once need to check some really sensitive circuitry, you will be at a loss.

In the end, it's your decision -- we can only help with thoughts and information to find the best solution for yourself.

Cheers,
Thomas
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #37 on: July 31, 2019, 10:25:57 am »
I was out for 2 days. Later when I get home I'll catch up with the thread.

Btw, the shop where I purchased my multimeter was TME.

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« Last Edit: July 31, 2019, 12:07:32 pm by psysc0rpi0n »
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #38 on: August 03, 2019, 08:25:19 am »
Hi.

I also need to consider space. It's a bit of an issue because as I'm just a newbie, I have all my stuff in my laptop desk which is already being expanded with sits. I have already stuff sitting on a sit next to my laptop esk on my living room... Adding to that, my laptop printer is also on this desk, so space is an issue. So probably I'm going either for the Siglent or Rigol. But still thinking about 2x of the single channel Korad. 60V and 5A is more than enough.
 

Online tautech

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Re: Basic Power Supply
« Reply #39 on: August 03, 2019, 09:02:00 am »
Double check measurements if you’re tight for room.
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Online Zorc

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Re: Basic Power Supply
« Reply #40 on: August 11, 2019, 06:50:29 pm »
So probably I'm going either for the Siglent or Rigol. But still thinking about 2x of the single channel Korad. 60V and 5A is more than enough.

I'm considering almost the same.
Still in doubt, but going for 2x the Korad KA3005P seems a very attractive option. In fact, I could do with just one at the moment and I could just buy another one when needed.
Going this route would be a lot cheaper then the mentioned Siglent, and even more then te Rigol.
This guy happily seemed to have swapped his Rigol for 3x Korad: https://youtu.be/EpIxw90Oku8

Seems that most of the past issues with the Korad supply are fixed. See for example: https://youtu.be/562U6G0XTDE
Ofcourse it isn't perfect, but thats also the case for the Siglent and the Rigol.
Specs wise the korads should be a great option, but I'm still not sure how they compare to the Siglent/Rigol, quality wise (i.e. reliability, noise etc.).
On the other hand, if one of the Korads would fail on me I could just buy another one and it would still be cheaper....
Must admit I kinda like the Siglent, but not sure if it is worht the price (for my use).


 

Offline electricMN

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Re: Basic Power Supply
« Reply #41 on: August 11, 2019, 08:54:13 pm »

Very similar to the Korad KA3305P (Programmable benchtop power supply, 3 channels (2x30V/5A, 5V/3A), parallel and serial mode for the 2 30V/5A outputs, 315W total power, 10mV/1mA resolution, USB/RS232 interface) 229,- EUR incl. 19% VAT. THe siglent has a smarter display if needed/preferred and my have better internal electronics. The Korad has better resolution 10mV/1mA.

https://www.welectron.com/Korad-KA3305P-Benchtop-Power-Supply

I have this Korad and like it a lot. I preferred a linear power supply for the lower noise. The transformer in it is huge. I've only used it a handful of times but will do some extensive testing of it in the fall when I get back to Arizona for the winter. I took it apart when I got it and nothing about it scared me. YMMV.  :)
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #42 on: September 14, 2019, 09:44:55 pm »
I still haven't bought the power supply. Priorities came in the meantime (daughter school stuff). But I'm under pressure now because the power supply I've been using for the past few years is of a friend of mine and he told me he will need it soon.

What you guys have to say about the above Korad posted in the previous post?
 

Offline J-R

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Re: Basic Power Supply
« Reply #43 on: September 15, 2019, 01:02:16 am »
I still haven't bought the power supply. Priorities came in the meantime (daughter school stuff). But I'm under pressure now because the power supply I've been using for the past few years is of a friend of mine and he told me he will need it soon.

What you guys have to say about the above Korad posted in the previous post?

I'm not sure which unit you're currently interested in, but I have the KA3005D ($65) and KA6003P($80).  Bought as returns from Amazon about 2 years ago.  Replaced fans immediately with temperature controlled units (probe on heat sink).  Software is basic and buggy, but does at least add some value.  Remote control of course, more memory buttons, logging, and a step function where it will follow a list of voltage/current/time values.

The 30V 5A unit is on the workshop bench, 60V 3A programmable is on the electronics bench.

They work, I got them for a good price, I'm happy enough with them.

 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #44 on: September 15, 2019, 09:17:39 am »
I still haven't bought the power supply. Priorities came in the meantime (daughter school stuff). But I'm under pressure now because the power supply I've been using for the past few years is of a friend of mine and he told me he will need it soon.

What you guys have to say about the above Korad posted in the previous post?

I'm not sure which unit you're currently interested in, but I have the KA3005D ($65) and KA6003P($80).  Bought as returns from Amazon about 2 years ago.  Replaced fans immediately with temperature controlled units (probe on heat sink).  Software is basic and buggy, but does at least add some value.  Remote control of course, more memory buttons, logging, and a step function where it will follow a list of voltage/current/time values.

The 30V 5A unit is on the workshop bench, 60V 3A programmable is on the electronics bench.

They work, I got them for a good price, I'm happy enough with them.

I was referring to the Korad KA3005P and Kora KA3305P. But I think I will go for the 2x Korad KA3005P. 2 real inependant channels (2 completely isolated grounds), more combined power (if 3x of this are compared with the KA3305P), cheaper because I don't need 3 of them, more space saving, more weight saving. I hope the buggy software is not that bad as you mention!

An will this "welectron" site be the cheapest site where the power supply is being sold?
« Last Edit: September 15, 2019, 09:22:42 am by psysc0rpi0n »
 

Offline ledtester

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Re: Basic Power Supply
« Reply #45 on: September 15, 2019, 09:46:36 am »
Let me propose another option for you:

https://youtu.be/bSkeV2ezuBs

- 32V, 5A output
- 4 digit displays for both voltage and current
- CC, OVP, OCP, OTP protection
- can be used in series and parallel configurations
- extremely lightweight and compact
- only $60
- has Voltlog's stamp of approval

It's not a linear supply, but in retrospect I've never needed a linear supply. The radio circuits / experiments I've done were all battery powered.
« Last Edit: September 15, 2019, 09:52:59 am by ledtester »
 
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Offline J-R

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Re: Basic Power Supply
« Reply #46 on: September 16, 2019, 08:10:28 pm »
I'd propose a 3A-5A linear supply and then a 10A or higher switch mode supply.  I have a 15V 40A unit.
 


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There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline rstofer

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Re: Basic Power Supply
« Reply #49 on: September 16, 2019, 09:25:24 pm »
Everybody gets to make their own choice. 

Rigol and Siglent pretty much dominate the space for economically priced test equipment.  I have the Rigol DP832 PS and it works fine.  The SPS3303X-E is about $160 cheaper than the DP832 (according to Amazon).  Either will do the job.

I'm not sure that the Rigol digital entry is worth $160.  Once a voltage is set, it pretty much stays set.  At least in my world...

Everybody around here expects tautech to promote Siglent but in my readings he has always been totally fair in describing features and failings.  I have the Siglent SDG 2082X AWG and it works great.

I am considering one of the Siglent scopes but until I buy one, I'll use my Rigol DS1054Z  Maybe that 350 MHz 2 channel Siglent since I already have the 4 channel requirement satisfied albeit at 100 MHz.

I have no particular brand loyalty, I just want reasonable performance for a reasonable price.
 

Offline dcbrown73

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Re: Basic Power Supply
« Reply #50 on: September 16, 2019, 09:30:54 pm »
Back in 2014, I bought a Mastech HY3005D  (0-30v 5amp psu) for $99 US.  It seems they are still $99US at Amazon.  While I have a new better PSU on my bench now.  It sits right next to it and I still occasionally use it.

I'm going to guess you can get them outside the US for similar price too.
Why exactly do people feel I should have read their post before I responded?  As if that was necessary for me to get my point across.
 

Offline rstofer

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Re: Basic Power Supply
« Reply #51 on: September 16, 2019, 10:49:58 pm »
Sometimes the overcurrent setting is set by shorting the output and adjusting the knob to set the current.  This is NOT the way I prefer to do the job.  On the Rigol you simply enter the value while the output is off.  That's much more rational, I want the voltage and current limit set before I turn on the output.  It might be worth looking at the User Manual.
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #52 on: September 17, 2019, 07:17:34 pm »
Let me propose another option for you:

https://youtu.be/bSkeV2ezuBs

- 32V, 5A output
- 4 digit displays for both voltage and current
- CC, OVP, OCP, OTP protection
- can be used in series and parallel configurations
- extremely lightweight and compact
- only $60
- has Voltlog's stamp of approval

It's not a linear supply, but in retrospect I've never needed a linear supply. The radio circuits / experiments I've done were all battery powered.

What is the advantage of that "linear" feature in a power supply? I just want to consider the possibility of not having it!
 

Online nctnico

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Re: Basic Power Supply
« Reply #53 on: September 17, 2019, 07:30:27 pm »
In general linear power supplies have less noise on the output. The cheap switching power supplies you can buy nowadays are (electrically) very noisy which makes them useless for developing circuits. The noise will swamp any detail in a signal you try to measure with an oscilloscope. Another problem is that the cheap switching power supplies need upgrading of the wiring to make them safe.
All in all switching power supplies are great as an adjustable high power wall wart but for use as a bench power supply not so much.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline ledtester

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Re: Basic Power Supply
« Reply #54 on: September 17, 2019, 09:47:22 pm »
What is the advantage of that "linear" feature in a power supply? I just want to consider the possibility of not having it!

As nctnico said, linear power supplies are less noisy than switch mode supplies. Switching supplies may not be suitable for circuits which deal with very weak signals. These signals are usually audio and RF signals.

However, there are several things to consider.

First, this GopherT power supply  has particular good performance wrt noise and this is demonstrated in the review. It is a whole lot better than the run-of-the-mill Chinese switching power supplies you find in the same price range. It is an order of magnitude better than your PC power supply which a lot of experimenters use for their projects.

Secondly, linear power supplies are easy to build yourself. You can get a kit for $10 and all you need to add is a consumer transformer wall wart. And if you really need a clean supply - like for a crystal radio or op-amp circuits - just use batteries which will be even cleaner.

I mention the GopherT option because you'll spend only $60 and it will serve you very well - besides being a lot smaller and lighter. You'll get current-limiting as well as enough power to do some interesting stuff like illuminate a car head lamp, fast charge a battery bank, light-up  hundreds of leds, drive a decent sized motor or solenoid ... These high-power applications do not require a linear supply.
« Last Edit: September 17, 2019, 09:51:19 pm by ledtester »
 

Online nctnico

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Re: Basic Power Supply
« Reply #55 on: September 17, 2019, 10:36:13 pm »
However, there are several things to consider.

First, this GopherT power supply  has particular good performance wrt noise and this is demonstrated in the review. It is a whole lot better than the run-of-the-mill Chinese switching power supplies you find in the same price range. It is an order of magnitude better than your PC power supply which a lot of experimenters use for their projects.
But is it good enough? I have a bunch of HP switching power supplies and I can't say they are low noise even though these are very well designed and have a lot of filtering at the output. I'm almost tempted to get a Gophert myself to test it. New mantra: I don't need another power supply...  :scared:
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline ledtester

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Re: Basic Power Supply
« Reply #56 on: September 17, 2019, 11:18:20 pm »
But is it good enough?

Of course that depends on the application. The Voltlog review measured < 10mv pk-pk noise at 5v, 0-5A output.

I am saying that a beginner has a lot of inexpensive alternatives if this doesn't work for a particular situation.
 

Offline Wirehead

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Re: Basic Power Supply
« Reply #57 on: September 19, 2019, 10:32:21 am »
I would buy just 2x Peaktech 6225A. Very decent power supplies imo. Doesnt take much room either since they are switching ones. From Reichelt one costs 75 euros so 2x will be excatly 150 euros. They will send all sorts of heavier stuff up to 10kg for 10 euros only all over the Europe.
I strongly recommend against using a switching PSU for developing circuits. There is too much (electric) noise coming from these power supplies making it impossible to measure small signals. Switching power supplies are great if you need a lot of power and don't have to care about ripple and noise so much.

In that case I would say do develop on a noisy PSU. It'll make sure your circuit is stable then. Local voltage regulation always trumps "expectations" of clean power.
"to remain static is to lose ground"
 

Offline Gandalf_Sr

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Re: Basic Power Supply
« Reply #58 on: September 19, 2019, 11:23:52 am »
If you can deal with the size, the old HP 66xxA power supplies e.g. 6642A or 6643A turn up on eBay for around $125 plus shipping; I've modified one to have front panel binding posts plus they are built like battleships and provide awesome quality output.

For new stuff but over your budget, I'd go for the Rigol DP832 which can be made into a DP832A without opening it up; I own one. I also own a Siglent SPD3303X-E which is OK but I think the DP832A is much better in several ways (binding posts, Ch3 can be set to any voltage withing 0-5.5 and has fully settable current controls) and the Rigol is so much more rugged.  As others have mentioned, there are some cheap, switch-mode power supplies available but their outputs are very noisy and I've stopped using mine for electronic work because it's caused me so many problems.

You mentioned a scope a while back, the Rigol DS1104Z.  Did you know that you can buy a Rigol DS1054Z and turn it into a DS1104Z in about 10 minutes without taking the back off it?
If at first you don't succeed, get a bigger hammer
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #59 on: September 19, 2019, 07:42:06 pm »

....

You mentioned a scope a while back, the Rigol DS1104Z.  Did you know that you can buy a Rigol DS1054Z and turn it into a DS1104Z in about 10 minutes without taking the back off it?

I have a DSO1104Z and I have already unlocked a bunch of features that would cost quite a bit to unlock by requesting them to the brand.

I have a power supply which was modified by a friend of mine using some board to allow to have +3.3V, -3.3V, +5V -5V, +12V and -12V but this friend of mine is going to need it. And I think I had quite a few problems because of it when I was working on my school project which was an RF application to measure VSWR of antennas. I was always finding new problems at home that I couldn't reproduce in the school lab when I met my tutor to help me fixing them. So I presume, at least, some of the problems where due to a poorly filtered power supply.

And I will probably go for the 2x Korad. But I'm still considering pros an cons.
 

Offline Gandalf_Sr

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Re: Basic Power Supply
« Reply #60 on: September 20, 2019, 09:47:36 am »
I own a Korad SDM3065X and it's OK in terms of the output where the voltage is reasonably accurate and clean (it's a linear supply rather than switched) but the user interface is a disaster; it involves pressing a channel button and then pressing in one of 2 knobs to see the digit that you want to change flash and then turn the knob to set that digit but then either the flashing times out or you want to change the digit to the left of the one you're working on and you have to step through all the other digits to the right to loop back around, why couldn't they have made it change the digit to the left as you pass from 0 to 9 going down?

The Rigol DP832 (DP832A after 2 minutes with a magic USB drive downloadable from here) has a funny-looking keypad but you pick a channel to control and enter whatever you want so 5.000 volts is just 3 presses to achieve; [CH],[5],[V]

So 2 Korads which maybe don't have the issues of my SDM3065X would be OK as long as they are linear not switched.
If at first you don't succeed, get a bigger hammer
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #61 on: October 20, 2019, 02:54:27 pm »
Well, I'm still thinking about this solution too. It was already suggested but I have been wondering about which to buy!

https://www.welectron.com/Korad-KA3305P-Benchtop-Power-Supply

This one already gives 3 channels but I'm not sure if there are any disadvantages on going for this option or for the 2x single channel.
 

Offline BillB

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Re: Basic Power Supply
« Reply #62 on: October 20, 2019, 03:00:17 pm »
I own a Korad SDM3065X...

Is that really the model number for the supply?
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #63 on: October 21, 2019, 10:28:19 pm »
Ok, I just purchased the 2 Korad KA3005P and 2 pairs of cables.
I'm just not sure if they come with power cables or not!
Hope they do. Otherwise I'll have to find 2 somewhere at home!
 

Online Zorc

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Re: Basic Power Supply
« Reply #64 on: October 22, 2019, 08:18:43 am »
Most likely you'll get power cables with them :)
Can you let us now how you like them (or not) or if you find any shortcommings in the current model?
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #65 on: October 22, 2019, 09:49:32 am »
Most likely you'll get power cables with them :)
Can you let us now how you like them (or not) or if you find any shortcommings in the current model?

Of course... I will. If you want I can run some basic tests. You just let me know what to do. Just a side note: I don't have a lab at home. Lol. Just one scope, one multimeter and a basic soldering station. Scope is Rigol MSO1104Z, multimeter is Brymen BM869s and soldering Station is Ersa I-Con Pico.
 
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Online Zorc

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Re: Basic Power Supply
« Reply #66 on: October 22, 2019, 01:31:39 pm »
Of course... I will. If you want I can run some basic tests. You just let me know what to do. Just a side note: I don't have a lab at home. Lol. Just one scope, one multimeter and a basic soldering station. Scope is Rigol MSO1104Z, multimeter is Brymen BM869s and soldering Station is Ersa I-Con Pico.

Maybe your first general impression (build quality etc.)  and if they function like you expected and just basic other things you notice when you start using them, i.e. set output voltage correct, overshoot/ripple/noise issues (with scope)
 
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Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #67 on: October 23, 2019, 10:26:16 pm »
Of course, I will...

Site says it was not shipped yet!

Edited;

I guess it will take some time. It says there "Shipping from 04/11/2019"... So probably they have no stock or something like that!
« Last Edit: October 23, 2019, 10:29:36 pm by psysc0rpi0n »
 

Offline exe

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Re: Basic Power Supply
« Reply #68 on: October 24, 2019, 08:27:47 am »
I like the iTech 6302 for around 500, only its still chinese crap.

Please define "crap". It's oem for tektronix, so I expect it to be at least half-decent. Teardown and some discussion was here: https://www.eevblog.com/forum/testgear/itech-it6302-power-supply-any-teardownsreviews/
 

Offline Jan Audio

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Re: Basic Power Supply
« Reply #69 on: October 28, 2019, 03:45:51 pm »
Please define "crap".

I tell you, take a look at these 2 videos at where they press the buttons :





Its all in perspective.
If you see the difference you wont invest 500 in itech.
The bad thing is the R&S price.
« Last Edit: October 28, 2019, 03:48:05 pm by Jan Audio »
 

Offline Black Phoenix

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Re: Basic Power Supply
« Reply #70 on: October 29, 2019, 11:03:00 am »
Lights are beautiful and everything, but I will take the beep over some buttons that light up...

I'm not saying that the quality of the R&S PSU will not be better than the iTech and that you probably can also turn on the beep sound on the R&S but I kinda like the display of the iTech, looking like the HP counterparts.

Although for viewing angles and functionality the R&S PSU display looks better.

That's why you have different price levels for different equipments.
 

Offline Jan Audio

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Re: Basic Power Supply
« Reply #71 on: October 29, 2019, 01:47:20 pm »
Its not about the lights, its about the build quality.

Ok maybe i still buy the iTech, it cost US $318.00 on aliexpress, + tax around 400 euro if bad luck.
Is it exact the same on aliexpress as in other stores ?
For 300 i buy it, not for more.
« Last Edit: October 29, 2019, 01:51:32 pm by Jan Audio »
 

Offline Black Phoenix

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Re: Basic Power Supply
« Reply #72 on: October 29, 2019, 02:31:38 pm »
Its not about the lights, its about the build quality.

Ok maybe i still buy the iTech, it cost US $318.00 on aliexpress, + tax around 400 euro if bad luck.
Is it exact the same on aliexpress as in other stores ?
For 300 i buy it, not for more.

Again I don't see your analogy, by picking up your post:


I tell you, take a look at these 2 videos at where they press the buttons :





Its all in perspective.
If you see the difference you wont invest 500 in itech.
The bad thing is the R&S price.

I saw both videos, and on the pressing buttons the only difference I saw is that one lights up and the other not but makes a beep confirming the selection. By seeing someone pressing buttons or see buttons light up or options showing on a screen I can't measure build quality because I'm not feeling. Nothing broke on camera, so for me both have quality.

Hypothetically speaking, If I didn't know any of the brands and I was starting now I would after watching both videos, check the specs of each one and the price and from them decide regarding my use case.

OF course, if you have a PSU that costs US$1,565.00, so basically 5 times minimum more that the iTech on ali for US$318.00, of course the extra money is brand (R&S is a big know brand), quality of construction and a nice interface plus some high end options.

Others to be competitive have to cheap anywhere, low end interface, worse construction, etc. Sorry but what I see is a comparison of Apples and Oranges.

One is a well priced entry PSU, other is a know brand high end one. Is the same as comparing a Iron bicycle with a Carbon one. Both are equal, both are used the same way, but one is way lighter (in competition that means seconds since it's less mass you have to move), costs a lot more, and in case of a fall is easy more breakable that the other (metal bends but is very resistant to single point pressure, carbon is very resistant to torsion but it breaks if a single point pressure is applied).
« Last Edit: October 29, 2019, 02:39:25 pm by Black Phoenix »
 

Offline Frex

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Re: Basic Power Supply
« Reply #73 on: October 29, 2019, 05:01:17 pm »
Hello,

I own some month ago a ITECH IT6302 power supply from Aliexpress (about 300€ with shipping).
It's a very good unit, very pleasant to work with.Build quality is very good.
I made also output noise measurements and it's very good (~60µVrms 10Hz-100kHz bandwidth Vo=12V 100mA).
I use  also Rigol DP832 PSU series, and i really much prefer the ITECH.
the Rigol is much bigger and the UI is no very good IMHO.
The ITECH have a great value for money.
The cons is that it is noisy when fan is active (same as Rigol).
The ITECH doesn't display output power (only U/I) as Rigol do, but not a big issue for me.
Note that this unit is rebranded to Keithley 2231A-30-3  and B&K Precision 9130.
As you can expect, they don't sale it at same price...

Regards.

Frex
 

Offline Jan Audio

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Re: Basic Power Supply
« Reply #74 on: October 30, 2019, 02:28:32 pm »
Did aliexpress write worth value : €10,- on the box ?
I want no tax also, else to expensive.
What country are you from frex ?
 

Online Zorc

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Re: Basic Power Supply
« Reply #75 on: October 30, 2019, 03:44:19 pm »
Did aliexpress write worth value : €10,- on the box ?
I want no tax also, else to expensive.
What country are you from frex ?

On a box like that with corresponding weight you need to be really lucky if it gets through customs without getting noticed., regardless the written value
 

Offline Frex

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Re: Basic Power Supply
« Reply #76 on: October 30, 2019, 04:45:00 pm »
Quote
Did aliexpress write worth value : €10,- on the box ?
I want no tax also, else to expensive.
What country are you from frex ?


I always take in account that i have to possibly pay the customs tax
 when i buy something outside EU (i'm in France).
This time i had to pay it. The seller had reduced the real value,
 and because the product is heavy, customs asked me an invoice and to pay the VAT.
So i finally paid 49€ of VAT to customs.
Anyway, a great PSU for the price !

Frex
   

 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #77 on: November 07, 2019, 09:21:29 pm »
Hello.

Well, I'm getting a little bit frustrated now.
When I paid for the PSU, it said in the site that it was available only after 04/11/2019. It's 7th November and the PSU has not even been shipped. I sent 2 emails to the support and they only send a copy of the email I sent them to my email address.

Am I in trouble? I bought it at welectron.com but nobody replies to me. Anyone had bad experiences with this site?
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #78 on: November 08, 2019, 11:43:11 pm »
They have replied to one of my few emails.

Quoting:
Quote
Regarding your order 34754: we are out of stock, incoming of goods is in about five weeks. However, we are glad to inform you that we still have two KA3005P Power Supplies left in our Warehouse. Through transport they got minor damages on the packaging unit. If you do not mind we will send those to you coming Monday.

Five weeks. And they want to send me damaged packages. This is not good for business. I asked them what they mean by minor damages in packaging. If they mean the hard paper box where they come is damaged or the PSU case itself. And asked them for pictures and also a compensation because I paid them as new.

What the hell??? Are they this bad? Jeeezzzz
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #79 on: November 16, 2019, 01:19:52 pm »
Well, I agreed with them to take the PSUs they have available. The damages are in the cardboxes so no stress at all. I asked a compensation and they refund me 10%.
It was just a shame that communication was quite hard and delayed! Hope I get the PSU's somewhere next week.
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #80 on: November 18, 2019, 10:39:33 pm »
Hello guys.

I just got my 2x Korads.

ISo, for the first test, should I just connect the PSU leds to my multmeter, set a value on the PSU and note it down in a Spreadsheet? Or what should I do? (I already did this).

For the Overshoot and other scope measurements, I think I need to spend some time learning how to properly filter out noise from scope and maybe other procedures to make it more accurate. I mean, if I short it's leads, I read weird things like too high Vmin and Vmax voltages of +/- 80mV with 1V / Div. If I zoom in up to 10mV /Div I get better values but looks like lots of noise.

Should I post the results of that first test I did? I'm not sure they are relevant.

I've just measured the following:
R - 470 ohm (464 ohm measured with Brymen)
V - 15V (14.97V measured with Brymen)

I = 30mA measured in Korad and 32.7mA measured with Brymen.

This might not be the best thing to do as I was using a 1/4 W resistor and drawing almost 1/2 W so temperature rises, resistance drops and current also rises, I guess. I don't have 1/2 W resistors I guess.

I did an OverShoot measuring with the scope but I'm not sure I did it correctly. I set the trigger level to 5V, Single Mode and turned the PSU ON. It read 5.439%.
I can take a picture tomorrow and upload it here if you want to see!
« Last Edit: November 18, 2019, 11:40:07 pm by psysc0rpi0n »
 

Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #81 on: November 21, 2019, 10:01:48 pm »
Of course, I will...

Site says it was not shipped yet!

Edited;

I guess it will take some time. It says there "Shipping from 04/11/2019"... So probably they have no stock or something like that!

Weren't you the one wanting to know more about the PSUs?
Well, I'm willing to run some tests but I need some guidance. I should mention I don't have a proper load to test the PSU's. Or better, I have 2 extreme loads. Regular resistors of 1/4W and an auto lead light bulb that draws almost the limit of the power supply. So, I on't want to force them this much.
Tell me what you would like me to do!
 

Offline Gandalf_Sr

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Re: Basic Power Supply
« Reply #82 on: November 22, 2019, 09:48:04 am »
Glad your PSU eventually arrived.  A few comments:

1. Running a 0.25 W resistor at 0.423 W for a short time (5 Seconds) should be fine, just be careful as the resistor may get hot and switch off if you see smoke.
2. If you set a current limit on your PSU output, you should be able to short out that output with a piece of wire and see the display show that current flowing, the voltage should automatically reduce to enforce the current limit you set.
3. If you have 4 x 1/4 W 470 Ohm resistors you can wire them up to make one 1/2 W 470 Ohm resistor like this...
 a. Wire two 470 Ohm resistors in parallel, you will have a 235 Ohm resistor with double the W
 b. Make another 235 Ohm resistor
 c. Wire the two 235 Ohm resistors in series
4. Car stop/tail light bulbs have 2 different filaments, 5W and 21W. Use your meter to measure the resistance of the filaments and whichever is the lower, that is the 21W filament.  Be aware that measuring the resistance cold will not be the same as when it's hot (i.e. lit up).

Pictures would be good.  FYI, I own a Korad PSU

[Edit] Have you seen

It shows that the PSU can get confused and output 56V !!!! FF to 29:00 onwards
« Last Edit: November 23, 2019, 12:51:19 pm by Gandalf_Sr »
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Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #83 on: November 22, 2019, 09:30:06 pm »
Hi @Gandalf_Sr.

Ok, I asked about the method of drawing some current based on some Dave video about testing a PSU for noise and ripple. But he used something I don't have which is a constant current sink or whatever is the name of it. It draws the current from the PSU and then he uses a scope to show and explain the results. He used like 2A and that's why I wanted something more than just a few mA.
So I came across with a simple example of a current sink circuit:


So I used for this circuit:
LM358N OpAmp
10nF cap
1k Ohm, 100 ohm and 2.4 omh (5x 10ohm resistors in // - the 2.4 ohm is real value, not theoretical 10/5 = 2 ohm)
IRF640 MOSFET N-Channel
For R_L I used different loads such as lead auto light (about 4.5A to avoid dropping 12V), desk light bulb of 1.5W and 5x 100ohm resistors in //. These 5x 100 ohm resistors still get hot with about 200mA.

Dave's video is this:


Edited;

I also did what you told me about the 470 ohm resistors. But it's still very low current. About 40mA if I set the PSU to 20V.



Edited 2;
With the circuit I posted above with the OpAmp and MOSFET, I can draw about 600mA for about a minute or so before the MOSFET and the sensing resistors get too hot.
Here are 2 screens:


« Last Edit: November 22, 2019, 11:30:15 pm by psysc0rpi0n »
 

Offline Gandalf_Sr

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Re: Basic Power Supply
« Reply #84 on: November 23, 2019, 10:21:09 am »
Dave has a BK programmable load (I have an old HP one), you set the current/Wattage/voltage you want and it trys to do that and shows you the actual current and voltage.  Inside it's got big power transistors fastened to big heatsinks with big fans.  If all you want to do check the ripple on the power supply when you pull say 2A from it, the simplest and cheapest way would be to use a 21W automotive bulb (turn signal) fed with 10.5 V.  The ones you bought are Linear so they should be pretty clean as far as ripple at half their rated load is concerned.

If you want something that's cheap and reusable you might try entering "electronic load" into eBay or Aliexpress, that will give you a bunch of cheap devices that range from some high-wattage resistors with switches ($3) to FET with a big (PC processor style) heatsink and fan with an LCD display that shows Voltage, Current, and Watts ($35).  I don't own one and can't tell you about its performance but beanflying has a couple he briefly mentions here.  Those loads probably use a microcontroller to regulate the drive to a FET. Your circuit is effectively a linear (rather than switching) solution and would work but it would cost you more to make it than the $35 one from China.
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Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #85 on: November 23, 2019, 06:28:45 pm »
Dave has a BK programmable load (I have an old HP one), you set the current/Wattage/voltage you want and it trys to do that and shows you the actual current and voltage.  Inside it's got big power transistors fastened to big heatsinks with big fans.  If all you want to do check the ripple on the power supply when you pull say 2A from it, the simplest and cheapest way would be to use a 21W automotive bulb (turn signal) fed with 10.5 V.  The ones you bought are Linear so they should be pretty clean as far as ripple at half their rated load is concerned.

If you want something that's cheap and reusable you might try entering "electronic load" into eBay or Aliexpress, that will give you a bunch of cheap devices that range from some high-wattage resistors with switches ($3) to FET with a big (PC processor style) heatsink and fan with an LCD display that shows Voltage, Current, and Watts ($35).  I don't own one and can't tell you about its performance but beanflying has a couple he briefly mentions here.  Those loads probably use a microcontroller to regulate the drive to a FET. Your circuit is effectively a linear (rather than switching) solution and would work but it would cost you more to make it than the $35 one from China.

Well, for now I just wanted to check how good/bad are these PSUs.
You said to check for OverShoot/Noise/Ripple issues.

This was what I wanted to check but I have no fancy devices obviously. I'm just someone that likes electronics but my knowledge and experience is very limited.
I like to do simple things and see other things working and understand how they work. I don't do this for living as it is obvious.
I like to program micro controllers just for fun. I like to build very basic things with discrete components. But even this is now more challenging to me because I stopped practicing since I finished my graduation and my job, despite the fact that is kind of related with my graduation, has very little or nothing to do with electronics and programming (I'm working as a project designer for fiber optic networks).

I didn't understand what you said about
Quote
Your circuit is effectively a linear (rather than switching) solution and would work but it would cost you more to make it than the $35 one from China.

You mean the circuit I built based on that image I posted above? If so, how would it be more expensive than a $35 one from China?
If not, what solution you're talking about that costs $35?
 

Offline Gandalf_Sr

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Re: Basic Power Supply
« Reply #86 on: November 23, 2019, 07:19:44 pm »
All I meant was that, by the time you bought all the parts to build your circuit, including a heatsink, it would be cheaper to buy a $35 load from China.  Plus your time.
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Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #87 on: November 23, 2019, 11:30:05 pm »
All I meant was that, by the time you bought all the parts to build your circuit, including a heatsink, it would be cheaper to buy a $35 load from China.  Plus your time.

If you're referring to the circuit I posted about to use as a current sink, I don't need to buy anything because I have all components here with me! And even if I had to buy them, they would be cheaper than $35. An OpAmp, a Mosfet, a couple of resistors, a capacitor and an heat sink would not be that expensive, I guess.
 

Offline Gandalf_Sr

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Re: Basic Power Supply
« Reply #88 on: November 24, 2019, 12:58:04 am »
OK on building from parts that you have but be aware that power in Watts = volts x amps so, if you ran 12V at 2A through the circuit you showed with a 1 Ohm resistor and an IRF640:

a. The resistor would dissipate 4W (power in a resistor is amps x amps x resistance (I2R))
b. The FET would dissipate 20W (12-2 (the voltage dropped over the resistor) = 10 x 2A)

This means that they would both get VERY hot so you'd need high wattage resistor and a heat sink on the FET.

Sorry if this is telling you something you already know.
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Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #89 on: November 24, 2019, 03:38:49 pm »
OK on building from parts that you have but be aware that power in Watts = volts x amps so, if you ran 12V at 2A through the circuit you showed with a 1 Ohm resistor and an IRF640:

a. The resistor would dissipate 4W (power in a resistor is amps x amps x resistance (I2R))
b. The FET would dissipate 20W (12-2 (the voltage dropped over the resistor) = 10 x 2A)

This means that they would both get VERY hot so you'd need high wattage resistor and a heat sink on the FET.

Sorry if this is telling you something you already know.

Yes, I'm aware but thanks for warning me.

My sensing resistor is not 1 ohm as in that circuit. It's 2.4 ohm. I didn't have any 1 ohm resistor. So I used 5x 10 ohm resistor (theoretical value should be 2ohm but I get 2.4 ohm).
Anyway, to prevent damaging FEt or resistors, I'm limiting the current to 600mA.

I also can use a light bulb from a desktop chandelier that can consume up to about 1.6A. And I don't need to be careful with heating components.
I did an experiment yesterday with the scope and this light bulb. The chandelier is rated at 12V, 20W max. This light bulb, according to the PSU, at 12V, draws about 1.6A (19.2W).

I don't have enough knowledge to analyse what the results mean.
I tried a few settings with the scope trigger. It was harder and uglier to measure the rising edge OverShoot (and I hope I did it right) than to measure the falling edge OverShoot.

For instance, when measuring the "connecting the load" scenario (rising edge), I can only get measurements from scope at time frames of 100ms and above.

Rising edge @ 100ms - 0.9644% OverShoot


Rising edge @ 200ms - 0.3624% OverShoot


Rising edge @ 500ms - 0.3496% OverShoot


Falling edge @ 2ms - 1.081% OverShoot


Falling edge @ 10ms - 0.3539% OverShoot


Falling edge @ 50ms - 0.3492% OverShoot


Falling edge @ 100ms - 2.306% OverShoot


Falling edge @ 200ms - 1.040% OverShoot


Falling edge @ 500ms - 0.3487% OverShoot


Power Supply:


My scope user manual says about OverShoot:
Quote
13. Overshoot: the ratio of the difference of the maximum value and top value of
the waveform to the amplitude value.

I can now test with an "heavier" load if needed. About 4A. Is it needed?
« Last Edit: November 24, 2019, 04:00:55 pm by psysc0rpi0n »
 

Offline Gandalf_Sr

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Re: Basic Power Supply
« Reply #90 on: November 24, 2019, 05:37:23 pm »
...I can now test with an "heavier" load if needed. About 4A. Is it needed?
Only you know what you "need".

If you want to know what the ripple is like at 4A, go ahead and test.  All power supplies have noise but linear supplies are similar and will typically have much lower noise than switched ones.  I own expensive HP and Rigol supplies plus cheap $99 linear ones including a 3-channel Korad that has the same button layout as yours.  I'd be more concerned that you could repeat Dave's case of confusing the Korad to send out almost 60V when it was set for 22V; a bit of noise is normal but sending out 3 x the set voltage is a potential disaster (pun intended).
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Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #91 on: November 24, 2019, 06:18:14 pm »
...I can now test with an "heavier" load if needed. About 4A. Is it needed?
Only you know what you "need".

If you want to know what the ripple is like at 4A, go ahead and test.  All power supplies have noise but linear supplies are similar and will typically have much lower noise than switched ones.  I own expensive HP and Rigol supplies plus cheap $99 linear ones including a 3-channel Korad that has the same button layout as yours.  I'd be more concerned that you could repeat Dave's case of confusing the Korad to send out almost 60V when it was set for 22V; a bit of noise is normal but sending out 3 x the set voltage is a potential disaster (pun intended).

Ok, I thought you wanted to know the OverShoot of these PSUs for comparison... That's why I was testing this. It's not that "I need" to know for any specific load.
 

Offline Gandalf_Sr

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Re: Basic Power Supply
« Reply #92 on: November 25, 2019, 12:26:56 am »
It wasn't me that asked for that.
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Offline psysc0rpi0n

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Re: Basic Power Supply
« Reply #93 on: November 25, 2019, 10:03:15 pm »
It wasn't me that asked for that.

Ohh, I'm sorry. It was @Zorc. I really sorry sir!
 

Offline Gandalf_Sr

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Re: Basic Power Supply
« Reply #94 on: November 26, 2019, 01:41:23 pm »
Not a problem.
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Offline eevcandies

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Re: Basic Power Supply
« Reply #95 on: November 29, 2019, 07:58:27 am »
There been a bunch of these supplies sold the last few months...some went for approx $50  , I got one for about $80 , plus shipping, like new.

https://www.ebay.com/itm/Kikusui-PMP16-1QU-4-Channel-06V-0-16V-016V-025V-Regulated-DC-Power-Supply/264451210613?epid=15025745400&hash=item3d92853d75:g:-n8AAOSwk2tcpoxW
 


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