Hey guys, I have designed and built this constant current/constant voltage power supply. I know it's a bit unconventional, but I've used a darlington pair transistor with a zener diode to regulate the voltage. The LM317 regulates the output current. The circuit does work very well with all sorts of loads. I now want to add short circuit protection, so I was just wondering how I would go about doing it. So far I''ve tried placing a PTC thermistor in series with the 16v Vin, and it works okay, except that the power transistor gets extremely hot (so I'm guessing it didn't really shut off the circuit). Any advice will be much appreciated. Thanks
so i simulated this circuit. the thing is that the two npn transistors will be using about 40W and 20W in the event of a short circuit. That's so high :/ any suggestions?
You show a DC input of 16V but also a 10V capacitor over the same point?
What are the voltage and current range you want this to work? The circuit will have very bad regulation as there is no proper feedback to compensate. At the moment, the output is only dependent upon the gain of the two transistors. That will change with temperature.
You show a DC input of 16V but also a 10V capacitor over the same point?
What are the voltage and current range you want this to work? The circuit will have very bad regulation as there is no proper feedback to compensate. At the moment, the output is only dependent upon the gain of the two transistors. That will change with temperature.