Author Topic: The electrically best solution for a stabilised 5V and 12V low current rail  (Read 747 times)

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Offline SK_Caterpilar_SKTopic starter

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So here I have a dillema about using a 7805 or 12 or to use just a shunt regulator.  Since the current is not really that critical, I mainly want the input voltage range to be as wide as possible. THe purpose will be of powering two MCP602 one as a triangle oscilator and the other as a error amplifier and and PWM comparator. I also use a TC4420P to drive a IGBT on the output. The worst I expect it to pull 100mA (and thats with quite the headroom from the absolute maximum). Im not really concerned about the efficiency because its really negligible. But heres the question, do I go with a 7805 and a 7812 or just a simple shunt regulator. Also keep in mind that the whole thing works at 56kHz so I think the zenner would work best, I think. I made sure there 10nF bipassing caps undeneath all of the chips so should really matter that much.

This is the most analog I could get with a PWM and the reason why? Well I built a 450V high power boost converter for a school project titled as "20W AB class vacuum tube amplifier".
So far the biggest problem was to get it actually pump out some power and when I got it working now it just goes scarry to about 50W no problems with that small flyback tranformer not even bothering that much. The other reason why I did not go with a TL494 is that it is trying to hold the output voltage very tight which is mostly good but not in my case. It creates all sorts of weird duty cycle artefacts and actual audiable noise so its not ideal, so I wanted to make a relatively "soft" supply. It has been tested works like a treat so far only noise issues (not audiably but electrically, what I did not count for is that the high gain stage basically picks up this noise and amplifies it loading the output tubes and creating weird stuff but I also solved that).
If someone wants to see the completed thing I can send a pic.

Apologies for the crappy grammar, im slovakian please dont judge me :D

Thanks.
« Last Edit: March 18, 2019, 09:04:08 pm by SK_Caterpilar_SK »
 

Offline chemelec

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Either a 7805 or a 7812 should work OK.
 

Offline SK_Caterpilar_SKTopic starter

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Either a 7805 or a 7812 should work OK.

I kind of want the best of the best instead of should work ok  ;D . I want the signals to be 100% clean and clear because this is a demonstration piece and who knows maybe even a production model lol.
 

Offline jaycee

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LM317 will have higher quality regulation of the output, especially if you use a 10-22uF capacitor on the ADJ pin.
If you want to go overboard stick an R-C filter before it.

http://www.tnt-audio.com/clinica/regulators_noise2_e.html
 


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