Show your favorite and most used benchtop PSU

[MikeK]

That's an awesome looking supply, I love it!

[BravoV]

However, the most used is probably this 190 watt baby, 'cause the whole family uses it -- even the grandkids!

Ok, I give up and still puzzled, is that a dc power supply ? I can see the selector from 0 to 20 volt though. Also two direction knobs ? and the red handle for A-whistle-B ? Really, I'm lost.   

From the look, must be very-very old, prolly dated back to WW II era ? 

[david77]

I'd say that's a model railway setup there and that's why even the grandkids use it, right?

@ BravoV: Thank you. I'll post some more pics & info later today.

[BravoV]

I'd say that's a model railway setup there and that's why even the grandkids use it, right?

@ BravoV: Thank you. I'll post some more pics & info later today.

Ha. ha. I'm such a noob, missed the grandkid clue. 

Thanks for the upcoming pics of your psu, can't wait to see the constructuon in detail. 

[david77]

As promised some info on my home made power supply.
As I said it's based on Elektor's lab PSU design from 1982, there's nothing special or fancy about it at all. I chose this design because I had the ideal transformer for it to hand. My former employer had a few of those ancient monster C core trannies that they sold for a really good price, it's got 2x29V/6A and 4x11V/1,6A secondaries which was perfect for the circuit published by Elektor in 1982.
The case is also home made as I could not find a reasonably priced case that suited my needs, this was supposed to be a low cost project and I didn't want to spend over 100 Euros only for the case. So I hit upon the idea to use the heatsinks as sides, that has been done before so why not? I had to buy them anyway as worst case dissipation is above 150W per supply if I recall correctly. They were the most expensive part of the whole design. I'm using 4x 2N3055 per supply, so this thing makes for a pretty good heater as well - no switching of secondaries here and it is capable of 5A @ 1V over long periods, I have tried it.
Initially I built it using four analog meters, but as you all know good ones cost a pretty penny so I skimped and bought the cheapest chinese crap I could find - they claimed 2,5% full scale accuracy but turned out to be more like 3-6% all ofer the scale.
Later I converted it to digital displays using the good old 7106. That turned out to not be as easy as I imagined - there is a separate transformer and four DC/DC converters in there just to get the displays going . Luckily the DC/DC converters were part of a load of huge boxes of electronic components I got for free.
About two years ago I wanted to power a car headlight (H4, 55W) and while doing that the one supply died. Magic smoke came out and that was it.
While investigating what had happened I found that it oscillated violently under heavy loads and some resistors in the original design were not specced powerful enough. I don't know if the original design using the proper PCB and cleaner wiring would behave the same but my tests lead me to think it's possible.
I ripped it apart, replaced the burnt out resistors, a died 2N3055 and placed small caps in the feedback loops of the two opamps to get rid of the oscillations. After some trial and error that worked and no matter what kind of load I hooked up it was now totally stable.
I also replaced my original hand wound current sense "resistors" (really just a coiled piece of copper wire) with precision resistors which cured some annoying inaccuracy with the amps meters  .
That was when I took the pics attached below.
Since then I also had to replace the low quality coarse voltage pots with high grade sealed units as the originals got a bit scratchy and this supply has the annoying habit to go full voltage when the wiper looses contact - not well designed!
All in all it works pretty well and apart from that one time it never played up. I've abused quite a bit - charging the car battery in a snow storm at -15°C with 2x5A and such things...
Total cost was an estimated 100 to 120 EUR.

[BravoV]

David77, thanks a lot for the pics and the story too, really appreciate it. 

The copper front panel + the green leds really matched each other since oxidized copper is green, really cool and nice looking steampunk style panel, love it.

About the circuit, I'm guessing from that era, its using the popular 723 chip ? What is the base made from ? Thick metal bar or strong and thick wooden plank ? Not very clear from the pics.

Look at that huge C core transformer, I think my Kenwood PSU has it and quite big if my memory serves me well, apart from the main huge E-I core transformer, wonder whats the purpose ? I will take a shot on the auxiliary C core transformer in it if I had a chance.

[david77]

Steampunk? 

The base and also the lid are made from some special sort of plywood, it's impregnated with something that makes it absolutely water proof and gives it a dark brown finish, sorry don't know what it's called in English.

There are 723's in there, yes. But they're only used as voltage references (7,15V). The actual control circuitry is built around two good old 741's.

[Madsaaby]

Hi

My, at the time, most used PSU!

HP / Agilent E3632a

0-15V @ 7A
0-30V @ 4A
1 mV and 1 mA res.

The only dislikes are:
Loud fan..
And I think it is too much "work" just set the Voltage and amp. I prefere the analog style where you just turn the damn knob.

- Mads

I posted photos + a small video here: https://www.eevblog.com/forum/reviews/hp-agilent-e3632a-120w-supply/

[SLJ]

Are you shorting the output measuring current?

[Madsaaby]

Are you shorting the output measuring current?

Yes..

[FenderBender]

Are you shorting the output measuring current?

Yes..

Badass

[SLJ]

Are you shorting the output measuring current?

Yes..

I've got one I dare do that with but it's not the HP....

[Madsaaby]

Are you shorting the output measuring current?

Yes..

I've got one I dare do that with but it's not the HP....

Well, as long as the current is limited, there should be nothing wrong with doing that..

- Mads

[Madsaaby]

Are you shorting the output measuring current?

Yes..

Badass

Sooooooo bad

-Mads 

[Spawn]

I got couple PSU’s on my bench, they are grouped up together.

I use my Xantrex for fine work mostly.
My favorite one is still old EA-4000, simply because it has everything I want:
AC from 0 to 240v and permanent leads 3v, 12v, 18v and 24v (2A)
DC till 30v 3A and permanent 5v 1A
Everything is nicely fused, it is big and heavy but still worth it





Here whole group together, on top shelf the Voltcraft one is my “portable”  PSU if I need it somewhere else than on my bench.

[BravoV]

Well, as long as the current is limited, there should be nothing wrong with doing that..

Yep, as long the PSU design and implementation is "properly" done, nothing to be scared of. I always did this test on every new acquired DMM or PSUs that have CC loop in the past either newly purchased or self built.

Just fyi, on cheap DMM that just using a piece of random thick wire as the shunt resistor for high current scale, let alone 10 Amps, sometimes even at < 5 Amps the accuracy will drift so bad once that wire is heated. 

[reagle]

Here are my two supplies. The one used daily is a BK 1698, picked off ebay and arriving with damaged front posts. Nothing some epoxy and a set of posts from RatShack store couldn't fix It's mostly well behaving, though setting limits is a pain and the fan gets noisy.
he secondary supply is an analog Tenma

[mariush]

Currently my only linear power supply, a Tenma 72-8695.

But planning to convert the power supply in the second picture to a 1.25-5v 7-10A  , 5v-12v 3A (maybe up to 15v?) power supply.  It's an old Delta 100w psu, 5v @ 13.5A , 12v @ 4.5A.  Should be fairly easy to mod it to boost the voltages a bit.

[SirDan]

My 100v super cooker. 

[Madsaaby]

My 100v super cooker. 

That's a beauty! I just love the look of those Power Designs supplies

-Mads

[mianchen]

I used to use this one a lot:



Then I got this one from eBay for cheap, and I've been using this one more recently.



There are a few DIY ones I like but without proper enclosure they are very messy to use.

[Rick]

Are you shorting the output measuring current?

Yes..

I've got one I dare do that with but it's not the HP....

Well, as long as the current is limited, there should be nothing wrong with doing that..

- Mads

But the output was off, and the UT-61E was in the Hold mode showing the previously measured current, right?
Otherwise how can you have 10 V displayed while the output is shorted?

[Madsaaby]

Are you shorting the output measuring current?

Yes..

I've got one I dare do that with but it's not the HP....

Well, as long as the current is limited, there should be nothing wrong with doing that..

- Mads

But the output was off, and the UT-61E was in the Hold mode showing the previously measured current, right?
Otherwise how can you have 10 V displayed while the output is shorted?

Nope The supply was outputting 3 amps at 0.something volts, but just showing the set values..

-Mads

[FenderBender]

My 100v super cooker. 

!!!!!!!!!!!!!!!!!TRANSISTORIZED POWER SUPPLY!!!!!!!!!!!!!!!!!!!

[HardBoot]

Is it bad my most commonly used power supply is a $20 12v computer supply with a filter and adjustable linear reg(10-turn pot fuck yeah) attached to a multimeter? More accurate than $150 benchtops, and keeps my desk warm...