- on Power Supplies
- Published in issue 12/2002 on page 0
Current Source with Indicator
There’s nothing new about a current source consisting of a transistor, a resistor and an LED to provide the reference voltage. However, what many people do not realise is that the LED provides an excellent indication of the proper operation of the circuit.First let’s review how this circuit works. The voltage drop across the LED is approximately 2 V, with practically the same temperature coefficient as that of the transistor.