I've mentioned that I had changed schematic a bit:
This is the current version.
The input capacitor is changed to 3300µF to filter out the input ripple.
The transformer is changed to a center-tapped with two 12v coils. LM315 is rated to dissipate 15W max. The calculations are pretty easy: P = (Vin — Vout) * Current. When I have 24v transformer input voltage is 30-32V RMS, so on low voltages it will overload the regulator quite quickly even with not high current (500mA). The best Idea is to use a transformer with two coils and a switch to change the input voltage from 12V to 24V when I need it. I plan to improve this part of the circuit later that it could switch automatically using a relay and an npn-transistor.
Another good improvement was a R3 resistor it allows to use all turns of the pot. 5K pot is a bit too much to use with 100Ohm resistor, but this resistor should be low (120Ohm max.) as it will lower the current on the adjust pin and regulator might not work properly. So for the full range of the pot a parallel resistor R3 is needed.
I still need to check if there any issues with the output switch. As there in no path to discharge C4 capacitor after switching the input on it may still keep some high voltage in it, so it can damage the connected circuit. I need to test this one when I build this thing up on the breadboard.
I need to say thank you to a great guy mariush form Martin's forum. He helped me a lot with all the calculations and improvements.
This is the current version.
The input capacitor is changed to 3300µF to filter out the input ripple.
The transformer is changed to a center-tapped with two 12v coils. LM315 is rated to dissipate 15W max. The calculations are pretty easy: P = (Vin — Vout) * Current. When I have 24v transformer input voltage is 30-32V RMS, so on low voltages it will overload the regulator quite quickly even with not high current (500mA). The best Idea is to use a transformer with two coils and a switch to change the input voltage from 12V to 24V when I need it. I plan to improve this part of the circuit later that it could switch automatically using a relay and an npn-transistor.
Another good improvement was a R3 resistor it allows to use all turns of the pot. 5K pot is a bit too much to use with 100Ohm resistor, but this resistor should be low (120Ohm max.) as it will lower the current on the adjust pin and regulator might not work properly. So for the full range of the pot a parallel resistor R3 is needed.
I still need to check if there any issues with the output switch. As there in no path to discharge C4 capacitor after switching the input on it may still keep some high voltage in it, so it can damage the connected circuit. I need to test this one when I build this thing up on the breadboard.
I need to say thank you to a great guy mariush form Martin's forum. He helped me a lot with all the calculations and improvements.
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