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5v off a steps construction

post #1 of 8
Thread Starter 
I'm putting a small DAC in the same enclosure as a headphone amp. I'd like to get a regulated 5v (or possible 7v for further down-regulation) from a steps power regulator circuit (with a suitable designed PCB).

I guess I can do this with an 78L05 with additional components, but I'm worried that the unregulated input to it would be too high causing it to become too hot. The steps setup will provide power for an M3 amp, thus the unregulated supply is at about 36v.

Should I rather use an additional LM317 (similar to the steps circuit regulator) and just down-convert the output with suitable resisters, or will a proper 78L05 circuit be able to down-convert from 36v to 5v?

Is there any other good way to get at a low power 5V supply without introducing any more transformers?
post #2 of 8
Not a chance you can drop 30V across a TO92 regulator like 78L05, and it's a very bad idea to drop that much voltage across one regulator in general.

You could probably take the output of the STEPS and drop it in steps, like 5V per regulator over a few LM317 regulators.

Easier option would be to simply use another wallwart or transformer and stick it in the same box as your STEPS. You'll have 1 IEC power entry and 2 power outputs. Just don't mix them up Personally, I'd suggest using a DIN connector so there's no chance of mess-up.
post #3 of 8
Quote:
Originally Posted by iampivot View Post

Is there any other good way to get at a low power 5V supply without introducing any more transformers?
36V to 5V is really a bit much for a linear power supply. A TREAD would work as long as the current drawn by the DAC isn't too high. A DC to DC switch mode supply is your best bet if you absolutly must run from the STEPS. Filter the output to get rid of any RF noise.
post #4 of 8
Welborne's PSREG is a great little psu. YOu can config it anywhere from 5V to 24V.
post #5 of 8
If your Steps transformer has a center tapped secondary or dual secondaries, you could tap off 18VAC for your DAC regulator. It all depends on the current draw of the DAC, your heat sinks and other particulars.

Neil
post #6 of 8
Quote:
Originally Posted by NeilR View Post
If your Steps transformer has a center tapped secondary or dual secondaries, you could tap off 18VAC for your DAC regulator. It all depends on the current draw of the DAC, your heat sinks and other particulars.

Neil
Where the heck you been, man? Step over to DIYForums and see what we've been doing lately.
post #7 of 8
Hi Tom,

I kind of got burned out last summer and my two failed Alien Dac builds made me question my sanity. I also got to thinking about how many headphone amps I really need to listen to my iPod :-).

But, yes, I've been lurking on diyforums and have had some discussions with Colin. That and the O11/O22/S22 is starting to make that itch fester again

Regards,
Neil
post #8 of 8
Quote:
Originally Posted by NeilR View Post
Hi Tom,

I kind of got burned out last summer and my two failed Alien Dac builds made me question my sanity. I also got to thinking about how many headphone amps I really need to listen to my iPod :-).

But, yes, I've been lurking on diyforums and have had some discussions with Colin. That and the O11/O22/S22 is starting to make that itch fester again

Regards,
Neil
Great! I hope Colin and Amb's stuff has you interested again!
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