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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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