LM311 Music LED

This article is about simple and low-cost music LED circuit that blinks with music.

Figure 1: Device.

I have reduced the cost of the circuit explained on this website: https://weirdcircuits.blogspot.com

Because the earphone plug has two channels the circuit also consists of speaker output (one to comparator input (left) and one to the speaker (right)).

You can see the circuit working in this video:

Step 1: Design the Circuit

I have drawn the circuit via PSpice simulation software.

Figure 2: Circuit Design.

The circuit does not allow microphone input because microphones need to be biased.

Step 2: Simulations

Simulations that the current is a bit small because the circuit also works with a 12 V battery.

Figure 3: Time-domain simulations.

You can reduce the value of Rled resistor to 680 ohms if you are using a 9 V battery.

Figure 4: Frequency domain simulations.

Step 3: Make the Circuit

I made the circuit with a wire wrap socket.

Figure 5: Make the circuit photo 1.

I used the soldering iron to attach the input from the earphone plug.

Figure 6: Make the circuit photo 2.

Step 4: Testing

The circuit was tested with a 9 V battery.

Conclusion

If you make this circuit you can try connecting the speaker and using the speaker as a microphone, connecting the speaker to the comparator input to see if you will get any LED blinking when you talk into the speaker.