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| Simple DIY Linear PSU |
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| xavier60:
--- Quote from: panoss on March 15, 2020, 10:40:03 am ---Ok, I got it! I lowered Vout to 8.89V. RL=no load, Vout=8.89V RL=20 Ohms, Vout=8.86V RL=10 Ohms, Vout=8.83V :-+ Wow! This is rock solid! --- End quote --- Well done for now. Depending on how much more experimenting you want to do. I would like D3 replaced by 2 forward biased signal diodes in series and the control rail changed to 7V. The zener diode does not need to be removed. |
| panoss:
--- Quote from: xavier60 on March 15, 2020, 11:04:44 am ---I would like D3 replaced by 2 forward biased signal diodes in series and the control rail changed to 7V. The zener diode does not need to be removed. --- End quote --- What are the signal diodes? Zener? (ok, I found it here. A 1N4148 is a signal diode) What shall I achieve with the signal diodes? Greater stability in Zener 's Vout? Which is the 'control rail'? The output of the LM317? And why should I change it to 7V? I'm gonna use it with Vin=15V or Vin=30V. If D3 (which is the zener diode) gets replaced, how the zener diode will not be removed? |
| xavier60:
--- Quote from: panoss on March 15, 2020, 11:15:11 am --- --- Quote from: xavier60 on March 15, 2020, 11:04:44 am ---I would like D3 replaced by 2 forward biased signal diodes in series and the control rail changed to 7V. The zener diode does not need to be removed. --- End quote --- What are the signal diodes? Zener? Something else? What shall I achieve with the signal diodes? Which is the 'control rail'? The output of the LM317? And why should I change it to 7V? I'm gonna use it with Vin=15V or Vin=30V. If D3 (which is the zener diode) gets replaced, how the zener diode will not be removed? --- End quote --- "Signal diodes" usually refers to small general purpose silicon diodes like 1N4148 or 1N914. The 2 diodes will drop the voltage across D3's location to about 1.4V. The original 5.1V zener will have no effect and can be left in circuit in case the mod has to be undone. I'm trying to achieve a control range at the Base of Q1 of about 4V. The output of the LM317 needs to be dropped to about 7V for it to work out. This can be achieved by going to a lower voltage zener but low voltage zeners don't regulate very well. |
| panoss:
You 're saying I should do this?: |
| xavier60:
Yes, its a very simple mod including the LM317 voltage change. I would normally try it here. |
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