- Blog entry posted in 'Having trouble analyzing this power supply..', February 25, 2016.
This is a power supply circuit I found while working on a project. I have been trying to analyse it but I am not getting the point of using Zener2 & Zener 3 in the circuit.
If anybody comes to know what it acts like or can relate it to something you already know, please send me a response.
97725 Thank you.
spec, March 02, 2016
Hi Elec, I am not sure about this circuit but it looks like a transformerless low current power supply. CAP2 is shown as 33mF which is 33, 000 uF, but that cant be right Neither can 33 uF be right because, living in India I am assuming that your mains supply is 240V 50Hz, the current flow would be too great and every component right of the bridge rectifier would be destroyed. Even assuming 3.3uf would give a current of 100ma RMS. This means that D1 would be dissipating 2.4W which is reasonable. So I will make this assumption. R25 Z2 Z3, R7 and NPN transistor are a classic constant current generator with a current of VfZ3/100 = 6ma flowing into b1 collector. The constant current generator does not make sense. Afraid, on the information provided I can't go much further. spec
