Whatfor do i need a LAB PSU ?

[JanJansen]

Hi, why do i need a laboratory power supply ?
Now i use a cheap thing like this :


I listen with my ear how much noise it makes for short circuit !
So i might need the lab supply for reading how much power the circuit takes ?

What is exact the money for, since they are very expensive.
I dont wanto buy a cheap chinese one : try and die ?

So whats the best choises ?,
i also wanto buy a scope and digital multimeter, is it best to first buy a good power supply ?

Thanks in advance, greetings

[tszaboo]

The lab PSU is needed, that you dont die, the circuit doesnt die, and it makes your life easier. It has current limit, which can be controlled by a knob, so if the circuit misbehaves, it will not start a fire or blow up. If you are serious about electronics, this should be the second thing you buy, first being a multimeter.

BTW, there is nothing wrong with the power supply you showed. When I was young, I've used a power supply designed for model train speed control. Thinking back, I should have bought something nice, it would be still usable now.
There are OK quality chinese power supplies, the trick is to know which one. Farnell sells Tenma branded power supplies, they are OK, has some quirks, but they work, and they are safe. The cheapest is about 70 EUR.

mod: Now I'm seeing, that yours is also Tenma.

[JanJansen]

Hi, i switched it on and off to many times, the on/off button is going to break, so i remove the powercable from the wall all the time, i need a new one for sure.
I have a multimeter, it works only the screen displays only 4 characters, just like my very old analog scope, it works only i want a nice digital one.
So i wanto replace all 3 things sooner or later : DMM Scope & PSU, i cannot afford all in one buy ( to bad ), else i needed at least 2000+ euro.

What do i buy ?, i realy like the Hameg / R&S gear, only the PSU is to expensive, what PSU do you reccommend and why ?, or are all brands good quality for such a simple thing ?

[WackyGerman]

You could also buy second hand stuff too . My first PSU I bought for 30 Eur was a really old one , made in White Russia . Still works good and it was fitted with screws , not with hot snot like the newer ones . Also got the manual with a parts list and the schematics . So it is repairable . If you find such an old puppy at ebay or somewhere else for a good bargain , then get for it . I made a teardown of it here in the forum

https://www.eevblog.com/forum/testgear/universal-power-source-made-in-belarus-teardown/msg485318/#msg485318

[JanJansen]

Hi, i,m looking to a PEAKTECH 6225 A,
not so expensive and new for around €75,-
Is it good ?

[rstofer]

I have been messing around in electronics at various levels for nearly 60 years and I FINALLY bought a Rigol DP832.  I have gotten by with fixed voltage linear supplies, batteries, wall warts, whatever, for a very long time.  I always wanted a decent lab PS but I can't say I have ever really needed one.  I bought it just because I could.  A true bench power supply, like the DP832, has a lot of very nice features and having 3 outputs, I can power up dual-rail op amps and a microcontroller all from one source.  That's pretty handy compared to what I was doing.

In my corner of the electronics sandbox, I would put a decent scope far ahead of a power supply.  Most of my projects are uC based and are usually powered by USB.  I can get along without the PS but I can't get along without a scope.

[The Soulman]

Or if you are in the Netherlands:

http://www.marktplaats.nl/a/hobby-en-vrije-tijd/elektronica-componenten/m1098225876-dubbele-tandar-type-ts3022-regelbare-voeding-30-volt-2-amp.html?c=a2384ef0ece270f44503df9f8598c624&previousPage=lr&pos=13

A TTI ts3022, I will let others comment on that one..

[MosherIV]

Hi

Yes, where are you based exactly?

As Soulman says, TTI (or Thurlby Thandar Instruments) have made very good basic lab PSUs for decades now.
If you are in the UK, they are very common and relatively cheap used.

If you are in the USA - then HP PSUs are probably common and relatively cheap used.

[ProBang2]

Peaktech does not build devices themself. It does only rebadging chinese OEMs.
Personaly I have prefered the Korad KD3005P (as D a little cheaper, also sold as Tenma and Vellemann).
Display with one more digit resolution, precise setting with rotary encoders and a dedicated switch for turning the load on/off.
(Costs around 90,- €)

I would avoid used PSUs. Sure, they can be great bargains.
But often enough: You only bought the sorrows from an other...

[JanJansen]

Peaktech does not build devices themself. It does only rebadging chinese OEMs.
Personaly I have prefered the Korad KD3005P (as D a little cheaper, also sold as Tenma and Vellemann).
Display with one more digit resolution, precise setting with rotary encoders and a dedicated switch for turning the load on/off.

If you look at Peaktech and Reichelt site you see the 6225A is the new version of the 6225, available from 14 november. ( i can think about it for 2 weeks before buying )
It has also exact what you say, on off button i think & more accuracy, looking good.

If this Peaktech is rebaged, what would be the original brand ?, maybe that one is even cheaper ?
I readed bad things about the Korad brand : try and die, Peaktech sounds somewhat more trustworthy to me.

I would avoid used PSUs. Sure, they can be great bargains.
But often enough: You only bought the sorrows from an other...

I agree, i dont wanto take any risk.

Or if you are in the Netherlands:

I updated my profile, look my flag now !, thanks for the link, i better buy new gear not second hand.

@ rstofer : LOL, after 60 years you bought a LAB PSU!
Thanks for the reply`s all

[JacquesBBB]

If you are serious in electronics, the first thing you should do is to fix your power supply. From what you say it is just changing the switch.

[PotatoBox]

You might want to consider building your own. A linear power supply is simple to make and is a good learning experience.

[JanJansen]

I am affraid for 220 volt, i only use 15 volt max, so repairing or builing that : no thanks.

[tszaboo]

I don't use a lab power supply (well, I have one, but I just use it as a normal 5V/12V PSU). I put all power management functions on board, so all of my boards only require one power jack input, and they generate their own voltage rails using on board converters.
If you design like me, you can safely use just a 12V or 5V power adapter to power up your boards. Don't forget to test for short using a DMM before applying power, and also put a fuse on board.
However, if you don't do complete product design, instead, you are more interested in building quick proto boards to verify circuits, then a programmable PSU can help a lot.

It is still better to power it with a lab PSU. You can create shorts when probing around, or the device can go into self-destruct mode. The fuse is used to protect the cable (catching fire), not safety or current limitation. Also some awful plugpacks can float themselves to half mains voltage. It will not shock you, but i can disrupt communication.

[JanJansen]

Ok, i agree it can save time with having a 3 output PSU unit.
I dont mind hooking up some 7805 and 3.3v regulators, still i would like to have a 3 out PSU,
Only why are those brands so expensive ?, Rstofer has a Rigol, its about the cheapest brand, still it cost 500.

So what is the big difference between the €75,- PEAKTECH 6225 A, and other brands like Rigol ?,
ok it has no 3 outputs, take for example a 1 output device from a brand, the casings look much bigger then the PEAKTECH 6225 A.

And what is the Earth (green) terminal for ?, on my current adapter i have only + (red) and - (black), i always thought earth was the same as - ?

[cs.dk]

A lab psu is floating. If you for some reason wanna ground it, you can use a shorting-bar between negative and earth.

Your own psu is probably also floating with respect to mains earth. Is the 230V cable with 2 or 3 pins?

[JanJansen]

Hi, the cable is 2 pins.

[cs.dk]

Then it is floating..

Floating lab psu's can be series or paralled coupled to gain more power output. Or to make a ie. +/- 15V supply. Don't do that with grounded psu's

http://powersupply.blogs.keysight.com/2014/03/what-is-floating-power-supply-output.html

[JanJansen]

Thanks, i try to understand, maybe i just dont use the earth at all, since i see no use for it, my final projects dont have earth also.

1 more thing about the peaktech, i read here all peaktech PSU`s are rebranded :
https://www.eevblog.com/forum/testgear/bk-precision-peaktech-only-rebranded-objects/
I try to find out what the original brand is of the PEAKTECH 6225 A, they say Manson or GW instek.
When i visit the Manson site i get a virus warning, what kind of brand is that ?

[FlyingHacker]

Lab supplies are useful mainly due to the current limiter. This will save you many $ in parts. 

Personally, I like older Linear supplies (Lambda). They are reasonably priced on eBay if you look around. They are through hole, and come with schematics/service manuals. You can learn a ton from repairing things.

Modern supplies, especially anything from China, are difficult to repair, as they are surface mount and have no schematics, and will end up in the landfill while the older supplies will keep running for many decades. I don't just st mean cheap supplies either. Nobody wants users to repair things anymore.

[ProBang2]

Hmmm...  "Peaktech" and "trustworthy". Somehow paradox.

Peaktech DMMs are usually from CEM. They are the OEM for many DMMs from Extech, too. And have ruined their reputation.
The Peaktech 6225 PSU is manufactured from MCH. http://www.china-mch.com/index.php/en/info/250.html
Just for interest: Teardown of a MCH-K305D (6225)
This company even managed to have a cheaper copy ("SM-8145", 33000 Counts) of the Vici VC-8145 (80000 Counts) benchmultimeter...

Unfortunatly: There is no information about the "6225 A" at this time. Too new? Hence: No confirmation right now possible.
 

[JanJansen]

Ok, i dont wanto try and die, i have some more money.
I dont get it why Reichelt sells it then ?
Luxury choises are difficult.

Wow, i,m looking to the Rigol DP832 YouTube movie, it makes a lot of noise,
i,m busy with audio, so i dont want any Rigol gear, those scopes also makes noise.

[Dave]

What sorts of currents do you need your power supply to deliver?
If your demands aren't too high, you might like HP/Agilent/Keysight E361xA series supplies. Lovely linear supplies, low noise output and no fans - just one hefty heatsink at the back. Exactly what you need for designing audio circuits.

[gamalot]

Hi, i switched it on and off to many times, the on/off button is going to break, so i remove the powercable from the wall all the time, i need a new one for sure.
I have a multimeter, it works only the screen displays only 4 characters, just like my very old analog scope, it works only i want a nice digital one.
So i wanto replace all 3 things sooner or later : DMM Scope & PSU, i cannot afford all in one buy ( to bad ), else i needed at least 2000+ euro.

What do i buy ?, i realy like the Hameg / R&S gear, only the PSU is to expensive, what PSU do you reccommend and why ?, or are all brands good quality for such a simple thing ?

Spend 1000 euros you can get Rigol DS1054z oscilloscope, Rigol DP832 bench power supply, and UNI-T UT61E multimeter from eBay. I think they are good enough to a beginner.

[CraigHB]

Earlier in this thread someone said a lab PSU is the second thing you should buy, the first being a multi-meter.  I would agree, but possibly a scope is second with a lab PSU third.  Good ones are expensive.  I was using those el cheapo Chinese ones, but the pots wear out fast and adjustments get jumpy.  I ended up replacing a couple of those units sooner than later. 

I bought a relatively cheap Chinese lab PSU with a rotary encoder.  It's great because there's no pots to wear out, but still wasn't particularly cheap at about 200 USD.  I'm actually on my second one.  The first one failed shortly after I bought it and fortunately the vendor warrantied it for me at no cost.  Even so the firmware is buggy and sometimes it reacts incorrectly to button pushes. 

Sometimes you end up paying more by cheaping out which I probably have on benchtop supplies.  I really, really need to get a good brand name supply, but don't have the money for it right now.  Has to have digital controls, don't want pots wearing out on me. I also need higher current and voltage limits since I've got a couple projects I want to do that need it.  Digital lab supplies with higher limits get really pricey.  It will probably be the most expensive of any test equipment I've bought so far. 

Don't really understand why quality benchtop supplies are so expensive considering you can get a decent scope for around four hundred USD.  A brand name digital lab supply with higher limits is greatly more than that.