| Electronics > Beginners |
| Discrete Regulated power supply |
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| HoracioDos:
Lol. Where can i hide? I was playing with some silly values to see if they make any difference. I should have fixed it before posting. PS: When I read your comment for the first time about 1000uf cap on the output I thought it was the 10000uf cap in the input after the bridge rectifier. That's the one I ment. Output capacitor is not mine..... :-DD |
| Cliff Matthews:
Elecktor had something basic back in '82 - should make you feel better. http://www.retro.co.za/zs1ke/projects/PrecisionPowerSupply/PrecisionPSU-Elektor-Dec-1982.pdf |
| not1xor1:
--- Quote from: blackdog on June 26, 2018, 06:43:43 pm ---Hi, All i see is schematics who do not care about phase marging... Like the schematic with 1000uF at the output, this must be a joke... |O Power supply's are not simpel! Can you build a good powersupply with discrete components, yes!, but you need to follow the same rules as with a opamp power supply. Anyone who wants to build power supply will have to learn what phase margin and gain margin is. And do dynamic testing. :-) Kind regard, Blackdog --- End quote --- I think the 220µF capacitor connected to the collector of Q2 is even worst than the output capacitor. |
| not1xor1:
--- Quote from: HoracioDos on June 26, 2018, 04:54:51 pm ---I see. I still don't have the skills to spot these things. Internet fooled me again, but it makes me wonder what I did wrong because I didn't see the ripple. I will check it again. --- End quote --- I guess you did not see any ripple because you were testing with no load or little current load and the 1mF output capacitor can easily take care of that. I think the first circuit showed at the start of the thread is much better although I would change it a bit with a couple of current sources and check better the open loop response. It is probably overcompensated. But there is no way a single 2N3055 can provide 0-38V/0-3A. It looks like somebody just do not have any idea about power dissipation, SOA, etc.. Another good source of discrete components PSU schematics could be the service manuals of of old (50-60 years ago) bench PSUs. |
| blackdog:
Hi not1xor1, Yes, its and, and bad :-DD First short circuits and gone is the 2N3055 |O The 220uF capacitor has a good funtion, and that is to keep the current trough R3 (Basis Q1) free of hum. A extra resistor between C3 and Q2 would resolf a big part of the extra pole. But... it is still bad! :box: The Elektuur design from december 1982 is a bit slow but a good design to start. It is not to difficult to make it better, but won't advise this for this beginners section. Kind regards Bram |
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