Basic Power Supply

[dcbrown73]

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.

[rstofer]

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.

[psysc0rpi0n]

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!

[nctnico]

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.

[ledtester]

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.

[nctnico]

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... 

[ledtester]

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.

[Wirehead]

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.

[Gandalf_Sr]

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?

[psysc0rpi0n]

....

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.

[Gandalf_Sr]

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.

[psysc0rpi0n]

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.

[BillB]

I own a Korad SDM3065X...

Is that really the model number for the supply?

[psysc0rpi0n]

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!

[Zorc]

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?

[psysc0rpi0n]

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.

[Zorc]

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)

[psysc0rpi0n]

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!

[exe]

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/

[Jan Audio]

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.

[Black Phoenix]

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.

[Jan Audio]

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.

[Black Phoenix]

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).

[Frex]

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

[Jan Audio]

Did aliexpress write worth value : €10,- on the box ?
I want no tax also, else to expensive.
What country are you from frex ?