Current Limiting Circuit Diagram. The resistor r1 is there to sense the current. Designed by andy collison.
Gnd r2 1k r1 14 load 12v gnd 5v q1 2n3904 q2 2n3904. R1 limiting resistor vref current. 9 volt 2 amp ps u a simple 9 volt 2 amp supply using a single ic regulator.
You would usually want to have a current limiting resistor in series with your led so that you can control the amount of current through the led.
I recommend using a multi turn potentiometer for better controlling current 0 05 a 9v battery clip and a 9v battery you can use the voltage souce to limit itself if the current limiter in power supply 0 41 2 wires with diffirent color an enclosure that fits the project if you have and some basic knowledge total cost. The figure shows a variable resistor for setting the current control however r1 can be replaced with a fixed resistor by calculating it using the following formula. Here is the circuit s schematic diagram. A simple method of sensing current this using resistors has been discussed in this article.
