Electronics > Projects, Designs, and Technical Stuff
variable power supply circuit
ArthurDent:
“…i am replacing the power transitor with pmos but it becomes very hot and temp goes on increasing.”
“…i completely understand the working but because i want to use single tap which is cheaper and for that reason i wanted to modify the circuit using mosfet.”
Whether you use bipolar or mosfets for the pass elements of a power supply, with the same design and same load you will be dissipating the same amount of heat.
You aren't understanding what everyone is explaining to you. Until you're willing to read and understand what they are saying, you will continue to have these overheating problems. There is a big difference between linear and SMPS topologies and once you understand that and design your power supply accordingly, it will work much better. Perhaps you should read some of the references suggested above to understand the basics before you try to build a power supply beyond your current understanding.
exe:
Peeps, I think this is a buck converter. Look at the diode, inductor and capacitor. Or at least the intent was to build one. I don't see any feedback.
mikerj:
--- Quote from: aneesh on June 18, 2020, 12:28:26 pm ---yes linear regulator but if you see its the opto pulses which switches the transistor on/off but i think am i not switching it on and off properly.
i have attached a ref circuit of another manufacturer.
--- End quote ---
That circuit appears to be part of a buck converter, it has the inductor, the diode and the output capacitor which are all required for a switching regulator. Where are these parts in your design?
aneesh:
ok i understand ...so i have to use some kind of pre regulator instead of multiple taps .. as transformer becomes expensive.
any reference of pre regulator
kallek:
Do you know what you are going to use your power supply for?
Because many times for example 20V/3A or even 1 amp is more than enough for bench power supply. And when you have working design you can modify it for higher current.
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