| Electronics > Beginners |
| how does blackdog's PSU work? |
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| blackdog:
Hi Hero999, You are correct, i dit not think of that... |O And I would like to add that if you test such a printed circuit board as I showed, you will isolate all mains connections! Also the live connection on the bottom of the board. When I test, I place a piece of plastic on the bottom so that I can not touch the live parts. And on the top side i use electrical tape to isolate the live parts. If you place a line transformer on the China boards, dril at least one row of holes around all the live connections. Make sure that all burrs from drilling are removed on both sides and clean the board with alcohol. So be carefull! Kind regards, Bram |
| exe:
Dear blackdog, what's the purpose of D13 and R39 on http://www.bramcam.nl/NA/NA-01-PSU/NA-PSU-50.GIF ? As I understand, D13 protects BJT's base from being pulled too low. Is this correct? R39 remove leakage currents from the base? So, I expect some current flowing through it. Can I connect it before the shunt resistor so this current is accounted? (although, I guess, this won't make a big difference). |
| blackdog:
Hi exe, :) You are correct, for the diode and the resistor! It is a good tip. I will place R39 in front of the 0.1 Ohm current sense resistance to lower the minimum current. Kind regards, Blackdog |
| AG7CK:
Quote: "The Harrison design i use (from the late 1950's) is really beautiful." Agree. Harrison manuals should be obligatory reading for anyone who is "building my own power supply". I find it amazing that none of the posters here seem to recognize that the topology you use is the hallmark of HP power supplies from the Harrison period until "modern" Agilent power supplies (and probably also Keysight-branded smaller bench supplies up until today [no schematics]). Anyone wanting to understand your "version" should start by reading Harrison Laboratories / HP Harrison / HP / Agilent manuals with theory of operation and schematics. There are dozens of them on the web. It hardly matters where you start because they are almost all based on the same theme: floating reference, dedicated bias supply and a current controlled linear power section. Those that are historically inclined can start here http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1962-07.pdf . |
| exe:
Thanks a lot, haven't read it yet, but looks like exactly what I need. |
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