Instructables PSU - Works?

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Instructables PSU - Works?

Post by Trippin » Fri Feb 07, 2020 10:45 am

The instructable I'm referring to is this: ... er-Supply/
Can anyone verify if this is possible?
The only method I've personally tried is one using non-isolated converters.
Kinda sus

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Re: Instructables PSU - Works?

Post by EATyourGUITAR » Sun Feb 09, 2020 8:10 am

lame. I don't want any clock noise in my power supply. I am building a power supply from laptop bricks right now but I never for one second decided that switch mode DC to DC converters would be better than LM317 and LM337 linear regulators. the only advantage would be that you can have a single 3A laptop power supply driving two LM2576-12 and one LM2576-5. it could therefor be simpler to connect your single laptop power brick on the 2.1mm barrel connector that came with it.

for two 15v laptop bricks I used this

so definitely more wiring and case building for the external power supply. I can still put inductors and caps on my laptop bricks just like the example you provided. the laptop supplies already have 52KHz oscillators in them. I want to filter that slightly before it leaves the external power supply case. this makes it closer to the ideal situation for low noise, like a linear supply feeding a linear supply. while the laptop bricks are switch mode, the filtering makes them closer to a crappy linear supply. because the laptop bricks are isolated, you can put inductors on each conductor and add a bypass cap after that. 4 inductors total for two 15v laptop bricks. the LM317 and LM337 require a minimum drop out voltage of 3v at full load. this system minimizes heat since it is exactly the minimum drop out voltage and we never load them to %100. as long as the heatsinks can handle it, you can probably get up to 1.2A per rail.

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Re: Instructables PSU - Works?

Post by vaxdatex » Sun Feb 09, 2020 3:47 pm

Not a big fan of switching supplies either. I designed my own ( which is
not that complicated. The only difference here is that I'm working with AC/DC transformers. Current limit with the 7812 and 7912s
used is 1A, the LM337 would go up to 1.5A. But put a 5A transformer in and you can run five of those off of it :).


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