Author Topic: Show your favorite and most used benchtop PSU  (Read 180018 times)

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Online capt bullshot

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Re: Show your favorite and most used benchtop PSU
« Reply #450 on: January 08, 2018, 01:47:57 AM »
It was my first PSU and I had build it myself - 35 years ago. I had no clue about design, no clue about electronics, there was no internet and no help far and wide.
Is it all the same with us EE's? Must have been around 1988 when I built my own lab supply - from similar prerequisites than yours.
I had a transformer, some electrolytic caps, fan heatsink and a few other components as a starting point. So I made this one from scratch:


The enclosure and digital meters were from Conrad, other parts purchased at a local electronics shop at Darmstadt (where I was an EE student then). All the electronics was build on perfboard, I didn't bother to draw a schematic diagram. Nobody told me a 250VA / 2x24V is not sufficient for a dual channel 24V / 5A lab supply, so built it to this spec. And, yes it worked. One can overload the transformer, I've attached a thermal sensor to it to keep it from overheating. I can't remember the details, but some way I've made a output stage out of 2 2N3773 and a BD139 that required only a bit more than the transistors Vbe drop to regulate, so the 24V goal was reached (with some ripple at max. current). I vaguely remember charge pump based auxiliary voltages of 5V below GND and 5V above input rail to do the trick.
The fan is temperature controlled (on/off) by temperature sensors mounted on the heat sinks, same sensors shut down the output in case of over temperature (this happens if you short the output at max. current setting).

The thing served me well until I found my way into TEA a few years ago, starting to buy fancy power supplies like the HP6632 and a quite unknown "Powerbox" that replaced my unit. It's still alive, but over the years some quirks found their way into it (e.g. the "---" display on one of the digital meters, or the not-always-working current limiting on one channel). Quite difficult to repair, since I never made a schematic and one needs to remove a lot of single wire to board connections to access the perf boards and the electronics. The voltage displays have a special feature: Auto-ranging between 9.99V and 99.9V fs range for better display resolution at lower voltages.



« Last Edit: January 08, 2018, 01:50:35 AM by capt bullshot »
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Online Calambres

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Re: Show your favorite and most used benchtop PSU
« Reply #451 on: January 08, 2018, 05:20:54 AM »
I've got mostly two PS:

The first is one I made when I was merely a kid. 24V and 8A. Short circuit proof and 2 x 2N3055 output stage. The initial case was much uglier than this and about 20 years ago I put it into this case and added a 220V fan. It has served me well for more than 40 years and only recently I had to change the *B-I-G* filter capacitor due to aging. Very low ripple.


The second one is my (now) most used PS. A chinese cheapie that turned out to be quite good. 0-32V and 5A. Also very low ripple. I hacked it a bit :) 

Now I'm making another one just for fun. This one is a dual PSserial/parallel based on two of these ubiquitous cheap chinese kits.

Offline emax

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Re: Show your favorite and most used benchtop PSU
« Reply #452 on: January 08, 2018, 05:38:53 AM »
Is it all the same with us EE's?

I'm not really an EE. More a wannabe. Sadly, it's  now too late for the university  ...

So I made this one from scratch:

This is WAY better than mine.  :-+

a local electronics shop at Darmstadt

Muhaha! Zimmermann? EBG ? Man, I'm from 64401 !  ;D

Where are you from? Send me a PM if you want!  8)


(funny to find local neighbours in an australian forum)
 

Offline MDM3D

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Re: Show your favorite and most used benchtop PSU
« Reply #453 on: January 09, 2018, 07:58:51 AM »
This is the bench powersupply I just made over the holiday and is now my favorite.  It uses 3 DPS5020s. The DPS5020s are feed 50V through 4 DPS 500 CB A  dell server supplies in series that can provide 45A for a total output of just over 2kw. The only bummer I have is that I only have the ability to supply 45V max out of the 5020's because they need to have at least 55V on the input. I built this mainly for electroplating and hard coat anodizing applications where lots of power is required and ripple requirements are low. As other have stated this uses low side current measurement and all of the precautions that apply with that.
I may in the future wind a transformer for 3KW with 3 1 KW outputs so that I could isolate and series the outputs. I have no ideas as to how I could go about paralleling due to the low side current measurement but would definitely appreciate 60A as hard coat anodizing requires 40 amps per surface foot.  It is really easy to get to a surface foot on relatively small parts like heat sinks.

I have the 1st "rail" in "filtered" with a 20000uF cap had laying around and quickly removed the small multi layered ceramic capacitors that blew up on Dave's testing video.
I ordered the communications versions and have plans to put an esp in to allow remote monitoring and simultaneous settings changes.

I also need to really run a 220V outlet to the bench because if I ever manage to completely load the psu then it will probably blow the 20A breaker it is attached to. 

The attached pictures were taken during the first time I turned it on before I moved it to the bench as it has a substantial amount of gravity to it.

Some quick testing with a dmm showed a Voltage ripple under 2mV for the first rail and under 9mV for the others when lightly loaded.
UNIVERSAL LAW 1, EVERYTHING runs on Smoke... If the smoke is released then it no longer functions. 
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Offline JustSquareEnough

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Re: Show your favorite and most used benchtop PSU
« Reply #454 on: January 09, 2018, 08:26:44 AM »
I've got mostly two PS:

The first is one I made when I was merely a kid. 24V and 8A. Short circuit proof and 2 x 2N3055 output stage. T

any details and pictures of the inside?
--David

hobbyist of electronics, woodworking, rocketry and other cool stuff. www.davidharms.me
 

Online Calambres

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Re: Show your favorite and most used benchtop PSU
« Reply #455 on: January 09, 2018, 07:04:45 PM »
The schematic is long lost (from an electronics magazine) and the PCB is the first I ever did so it's not pretty  :)

One of these days I'm gonna open it up and try to trace the schem. I'll take some photos and post them here.
« Last Edit: January 09, 2018, 07:06:49 PM by Calambres »
 

Offline jayjr1105

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Re: Show your favorite and most used benchtop PSU
« Reply #456 on: February 14, 2018, 10:48:51 AM »
My one and only, homebrew.  12V5A switching supply with LTC3780 doing all the magic.
 


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