Can anybody please help me with this prob?? I need a 5V supply which the input supply should be around 50VDC and should be able to withstand around 5A. I tried the circuit below and it fails just after exceeding 2A. is anything wrong I have done with the circuit?? or I'm well appreciate, if anybody have a better circuit..
WHATT ?????? it'll destroy the circuit connected to output.. coz as per the simulatuion, then it'll have the input voltage at the output...... !!!!!!!!!!!
Can anybody please help me with this prob?? I need a 5V supply which the input supply should be around 50VDC and should be able to withstand around 5A. I tried the circuit below and it fails just after exceeding 2A. is anything wrong I have done with the circuit?? or I'm well appreciate, if anybody have a better circuit..
Thank you...
2N3055 transistors have quite low current amplification factor, so a 1W 33V zener diode will definitely not be able to deliver enough current to its base to produce 5A of I[c] current ..
Simple calculations for, say, H[fe] <20 will show you how much base current will be required for 5000mA output …
7805 input = 13V. Current delivery from 7805 = 550mA.
P=V*I=(13-5)*0.55=4.4W!
Is this just a schematic for educational purpose or it will be transformed into a real world circuit?
I think that the above calculation justifies a question like that.
Also, consider the overall circuit. Power loss = (50-5)*5 = 225W for an output power of 25W. Efficiency = (25/250)*100% = 10%
So, for a more efficient circuit, a switching regulator should be employed. There are switching regulators available for 5A current or more. One such is L4977 (7A output).