Various Power Supply based project is already available in bestengineeringprojects.com like short proof variable power supply, stabilized power supply with short circuit indicator, Universal digital power supply, variable switching power supply etc. Now here is a very simple circuit of short circuit protected regulated power supply utilizing very few components.
Circuit Description of Short Circuit Protected Power Supply
The circuit short circuit protected variable power supply utilizing an op-amp 741, two npn transistor and few passive components. Unregulated or fluctuating voltage is first regulated and smoothens by diode D1, and zener diode ZD1. Resistor R5 is used as current limiting resistor. The output regulated voltage is given to non-inverting pin (pin 3) of IC1. Output of IC1 from pin 6 is given to base of series regulator transistor T1 through resistor R2. Inverting pin of IC2 is connected to voltage divider circuit at output. At beginning difference between its inverting pin (pin 2) & non-inverting pin (pin 3) make transistor T1 ON. According to input voltage of IC its output voltage also changed which is given to base of transistor and as a result output voltage is controlled.
Transistor T2 is used here for short circuit protection. If output current is increased or when short circuit occurs, voltage across resistor R3 is also increased which make transistor T2 ON. When transistor T2 is on it gives reverse bias to transistor T1 and as a result no output voltage is available. In this way the circuit short circuit protected regulated power supply provide regulated power supply with the facility of short circuit protection.
PARTS LIST OF SHORT CIRCUIT PROTECTED REGULATED POWER SUPPLY
Resistor (all ¼-watt, ± 5% Carbon)
R1 = 200 Ω
R2 = 47 Ω/1W
R3, R4 = 10 KΩ
R5 = 4.7 KΩ
VR1 = 47 KΩ
C1 = 470 µF/25V
C2 = 100 µF/25V
IC1 = µA741
T1 = SL100
T2 = BC148
ZD1 = 1W
D1 = 1N4007