t_malavika
New Member
Hi all,
I need some help in figuring out the function of some components in an adjustable power supply using LM317.
The previous stage in the shown circuit is a bridge rectifier
The PCB has 2 transistors 2N4401 coonected as shown and with an LED.
what is the purpose of the transistors and LED.
I understoof the circuit of the LM317 ok. But why the zener there? it is a ZN423.
Also i'm not able to recognise the component drawn as a box between the capacitors c1 and c2. It has just "5%" printed on it. It looks the size of a half watt resistor and but feels ceramic.also why c1 and c2. are they both as filters here? why is + of C2 earthed instead of the supply negative itself?
Could someone please help out.
Thanks a lot
I need some help in figuring out the function of some components in an adjustable power supply using LM317.
The previous stage in the shown circuit is a bridge rectifier
The PCB has 2 transistors 2N4401 coonected as shown and with an LED.
what is the purpose of the transistors and LED.
I understoof the circuit of the LM317 ok. But why the zener there? it is a ZN423.
Also i'm not able to recognise the component drawn as a box between the capacitors c1 and c2. It has just "5%" printed on it. It looks the size of a half watt resistor and but feels ceramic.also why c1 and c2. are they both as filters here? why is + of C2 earthed instead of the supply negative itself?
Could someone please help out.
Thanks a lot