Introduction: Light Drivers

About: We are a group of people that design amateur electronic circuits.

In this Instructable you will be simulating a light driver circuit.

There are many LED driver ICs (integrated circuits) that a sold on the internet. However, if the IC becomes obsolete you cannot fix your circuit.

However, this instructable shows a good voltage regulator IC that can be used for driving LEDs with currents as high as 3 Amps:

However, there are cheaper voltage regulators.

The LED component is modeled with three diodes because this component was not available in the old simulation software.

For high power applications, you need to increase the voltage and add more LEDs in series and parallel connections.

Nowadays you can purchase very bright, higher current LEDs on the internet. You might need to use high power/current/voltage rating transistors and bigger heat sinks.

The applications of this circuit include:

- automatic light control (turn on in the dark light),

- connecting the input to PWM (Pulse Width Modulator) that can control the brightness of the bright LED. This is useful for the concert lighting,

- glowing toys.

If you do not have PWM controller then you can try building:



However, those circuits are analogue and might become obsollete if the new devices are not produced with music lineout/speaker/earphone outputs. Yet there is an option of you building your own microphone amplifier.

The simulation steps of this instructable show how transistors saturate to reduce the power dissipation.


Simulation Software. This could be online and software that you download and install. I used old PSpice Student Simulation software only to reduce the circuit drawing due to keyboard short cuts that modern software does not allow.

Step 1: Draw MOSFET Circuit

Old PSpice software was used to reduce time due to keyboard short cuts.

Step 2: Simulate MOSFET Circuit

Simulations show a fast response time of MOSFET circuit.

Step 3: Draw BJT Circuit

I have drawn a BJT circuit because some MOSFET have low maximum gate-source voltage. This is probably the only advantage that a BJT transistor has over MOSFET for those particular applications.

Step 4: Simulate BJT Circuit

Simulations show a fast response time of BJT circuit.

You are now done.