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Simple DIY Linear PSU

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panoss:
To change LM317 's Vout I must change R16? Or R17? Or something else?

xavier60:

--- Quote from: panoss on March 15, 2020, 11:50:25 am ---To change LM317 's Vout I must change R16? Or R17? Or something else?

--- End quote ---
Try R17 first. ll try to work it out here.

xavier60:
680Ω for R17 will set it to a bit under 7V.

panoss:
Ok, I did the mods:
R17 = 680Ω
Two 1N4148 in place of D3, voltage across them is 1.22V.

Also I changed Vin to 18V.

RL=no load, Vout=16.93V
RL=20Ω,      Vout=14.61V
RL=10Ω,      Vout=13.34V

I lowered it to 12V.
RL=no load, Vout=12.04V
RL=20Ω,      Vout=11.99V
RL=10Ω,      Vout=11.96V

So at lower voltages it 's more stable.
Maybe if I put a second transistor it 'll be more stable at higher voltages?

xavier60:

--- Quote from: panoss on March 15, 2020, 01:02:22 pm ---Ok, I did the mods:
R17 = 680Ω
Two 1N4148 in place of D3, voltage across them is 1.22V.

Also I changed Vin to 18V.

RL=no load, Vout=16.93V
RL=10Ω,      Vout=14.61V
RL=20Ω,      Vout=13.34V

I lowered it to 12V.
RL=no load, Vout=12.04V
RL=10Ω, Vout=11.99V
RL=20Ω, Vout=11.96V

So at lower voltages it 's more stable.
Maybe if I put a second transistor it 'll be more stable at higher voltages?

--- End quote ---
As the amount of current approaches a transistors maximum rating, the gain usually drops a lot.
What maximum current  do you need?
The   TIP35C transistors in my bench supply have a combined current rating of 50A to handle 5A. This isn't unusual.
What is Q1's Base voltage with the output voltage set to 9V unloaded?

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