Author Topic: Show your homemade power supply  (Read 1282 times)

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Offline gcewing

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Show your homemade power supply
« on: September 25, 2021, 10:28:23 am »
I had my Frankensupply open for an upgrade, and thought I'd take some pictures to post here.  Stitched together from the dismembered corpses of various pieces of equipment, it provides power for many of my mad scientist experiments.



The transformer and most of the rectifiers and capacitors are from a dot-matrix printer. The power cord, power switch and input filter are from a daisywheel typewriter. The case once housed an 8-track cartridge player. The regulators and heatsink were bought for the purpose (I needed a fresh, young heart).

The upgrade was adding a 36V output for jolting stepper motors into life.



Anyone else have a unique power solution they'd like to share?
« Last Edit: September 25, 2021, 10:31:09 am by gcewing »
 
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Online ledtester

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Re: Show your homemade power supply
« Reply #1 on: September 25, 2021, 02:39:11 pm »
How does this work? Are you using two Euro style terminal blocks to create a plug so that you don't have to unscrew any of the colored wires to disconnect the front panel?

[attachimg=1]
 
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Offline gao415517

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Re: Show your homemade power supply
« Reply #2 on: September 25, 2021, 02:47:08 pm »
Handmade
 

Offline gcewing

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Re: Show your homemade power supply
« Reply #3 on: September 26, 2021, 04:11:02 am »
Are you using two Euro style terminal blocks to create a plug so that you don't have to unscrew any of the colored wires to disconnect the front panel?
It's one of these:
https://www.jaycar.co.nz/plug-socket-12-way-screw-terminal-strip/p/HM3202
 
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Offline Terry Bites

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Re: Show your homemade power supply
« Reply #4 on: September 26, 2021, 04:40:40 pm »
Current limit is dodgy though....
 
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Offline SmokedComponent

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Re: Show your homemade power supply
« Reply #5 on: September 27, 2021, 11:09:38 am »
My weekend take at "μSupply" years ago; 0-10V, 0-0.5A linear supply with op amps. Normally runs on Ni-MH but now I'm pushing my luck...  :scared:
[attachimg=1]
 

Offline Axel_sr

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Re: Show your homemade power supply
« Reply #6 on: September 28, 2021, 04:08:25 am »
3-13VDC
 

Online BU508A

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Re: Show your homemade power supply
« Reply #7 on: September 28, 2021, 08:16:06 am »
“Chaos is found in greatest abundance wherever order is being sought. It always defeats order, because it is better organized.”            - Terry Pratchett -
 

Offline Avelino Sampaio

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Re: Show your homemade power supply
« Reply #8 on: September 29, 2021, 08:45:40 am »
Hi

It took me 6 months to complete this project. It was an amazing learning experience! My challenge started with the implementation of a Mosfet, for Soft Start control. Mosfet had two other functions: RDS_on in the composition of the CRC filter and interrupt key for the OVP and OTP system.

Details of the development at the link below

https://www.diyaudio.com/forums/power-supplies/368845-functions-mosfet-crc-filter-soft-start-sense-5.html
« Last Edit: September 29, 2021, 09:05:40 am by Avelino Sampaio »
 

Offline Thomas

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Re: Show your homemade power supply
« Reply #9 on: October 02, 2021, 08:23:58 pm »
Designed and built back in the college days :)
Made the PCB at school, in the PCB lab. Did not work first time, quite a few revisions to get rid of the oscillations :-DD
0-25V, 0-2.5A with an ATmega8 for setting the references for the output (PWM), and for measuring voltage and current (internal ADC).
It also has a RS-232 port and a DS18S20 temperature sensor for controlling the fans.

Still works fine, and I use it quite a lot.
« Last Edit: October 02, 2021, 08:45:42 pm by Thomas »
 

Offline TheMG

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Re: Show your homemade power supply
« Reply #10 on: October 03, 2021, 07:09:00 pm »
My first foray into building a bench power supply (about 10 years ago). Essentially two completely independent linear regulated power supplies in a single enclosure, each capable of 30V up to 3A.

The case, transformers, heatsink, pass transistors, bridge rectifiers, and a few other components are salvaged from e-waste.

In the first picture, modifying the toroidal transformers. I added a couple of taps to the main secondary winding, these are selected by relays to reduce power dissipation in the pass transistor at lower voltage settings or when the power supply is in current limit. I also wound an additional auxiliary winding on top to provide power for the control circuits.

Pic 2: front panel assembly.

Pic 3: once the front panel and transformers were assembled as well as the pass transistors on heatsink, it was time to prototype and test the circuit on breadboard

Pic 4: etching PCBs using the toner transfer method, and extremely caustic hydrochloric acid / hydrogen peroxide mixture as etchant (rather dangerous compared to ferric chloride, but all the necessary chemicals can be obtained at any hardware store, and the only option for me obtaining ferric chloride is to order it online)

Pic 5: assembled PCB. the connectors are of course yet another salvaged part, and they are a much nicer alternative to soldering the wires direct to PCB, in case further modifications or repairs of PCB are ever necessary, it can be easily removed

Pic 6: PCBs mounted above transformers on custom made aluminum brackets, time to finalize the wiring!

Pic 7: with the wiring all cleaned up and rear panel installed

Pic 8: done (except for labelling the controls). big knobs are voltage settings (10-turn pots), small knobs are current limit setting (single turn)

It's not going to win any awards as far as how clean the output is (does have a few mV 120Hz ripple, probably due to using the output of LM7812 as the voltage reference rather than an actual proper voltage reference), but it's good enough for my needs and I still use it fairly regularly even to this day. I could make some improvements to it but just haven't bothered.

 


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