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| 10 Amps power supply with LM723 |
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| iMo:
When the pot's wiper is at the lower side the BE voltage cannot be higher than 0.16V. The Vref is say 7.2V and the divider is 120/(4k7+500+120)*7.2=0.16V. |
| mike_mike:
Yes. When the pot is at lower side and the output voltage is at minimum, then the BE voltage is 0.165V. But if I rotate the Voltage pot, then the BE voltage increases slowly from 0.165V to 0.595V, even if the current pot is at the lower side. |
| iMo:
There is a wiring problem then. When increasing the output voltage, AND the current through the shunt is low (say 10mA), the BE voltage should not change much. With set constant 0.165V at the current limit pot you would need 3Amps through the 0.15ohm shunt to get 0.6V at the base-emitter. |
| mike_mike:
I built another schematic, and I hoped that it will work. But it doesn't and I do not know why. When I power up the circuit, the 500R trimmer gets hot and the output voltage is always about 32.5-33Vdc. I changed the LM723 with a new one, I changed the 10K pot with a new one, I changed the power transistor (for the tests I used only one power transistor) with a new one. I also checked the layout and the PCB and there are no problems. :palm: :palm: :palm: This schematic is 100% functional, it was build by someone from my country and it works. What should I do ? |
| iMo:
I've done a simulation of your original schematics above and it works. FYI: CL POT Current LIMIT (14.6V Vout) 5ohm 3.17A 250ohm 1.00A 300ohm 0.55A 330ohm 0.29A 350ohm 0.12A |
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