W A R N I N G !

W A R N I N G !

This page is full of non-facts and bullsh!t, (just like the internet and especially forums and other blogs), please do not believe entirely without exercising your intellect. Any resemblance to real things in reality is purely coincidental. You are free to interpret/misinterpret the content however you like, most likely for entertainment, but in no case is the text written on this blog the absolute truth. The blog owner and Blogger are not responsible for any misunderstanding of ASCII characters as facts. *cough* As I was saying, you are free to interpret however you like. *cough*

Saturday, March 5, 2011

Almost completed - Linear post regulator

I needed a 15V power supply to replace a dead one. And something at least 2.5A.

But there are two issues:

- 15V power supplies of >2.5A are significantly more expensive than the more common 19V (at the time of my searching)
- Always expect worst-case scenario when not proven otherwise - the DC quality of these power supplies are crap. And when I say crap, it is more crap than a typical desktop computer power supply. Much more crap.

Hence the idea of using a linear regulator + filter to clean up the circuit and drop the voltage at the same time came up.

Thanks to a group of helpful and knowledgeable enthusiasts over at diyAudio forums a good design was created very quickly. I implemented one of the earlier designs but the topic has progressed even further.

I will not post the design I used out of respect for the community by keeping the internet free of bad circuits when superior ones exist, but basically the idea I used was capacitor multiplier with one RC stage at the base of the darlington, fed to a LM338 linear regulator.

I so need a camera. PC Show coming soon.

Missing input connector and output strain relief. Grommet I got was too small.

P2p build, active devices bolted to the tin case which doubles as a heatsink.

I'm getting 38°C with no load and 46°C with load for the LM338, and 34°C no load 38°C load for the transistor, taken directly from metal part of the TO-220 packaging. Same 29°C air temperature. Compare it with the 47/54 heatsink temp with the Zhaolu power supply.

I don't know if this or having the cover closed, and the surface with the components bolted-on flipped over to face the top would provide better cooling, but for certain, at these temperatures and power draw, it would not matter.

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