Simple Circuits: Op-Amp Sound Light

This article shows you how to make a simple sound light circuit with an operational amplifier.

I thought of this idea after reading the following article:

My circuit is simpler, needs fewer components, can work with microphone inputs but can only drive loads of just 10 mA.

Step 1: Design the Circuit

The input to my circuit is a microphone modeled with 500-ohm output impedance.

Figure 1: Circuit Design.

The bright LED is modeled with three general-purpose diodes.

Step 2: Simulations

Output Transient Analysis:

Figure 2: Transient Simulations.

The load current is about 10 mA which is the appropriate current for bright LEDs.

Spectral Analysis:

Figure 3: Frequency Simulations.

The bandwidth seems to be very high for Rf value of 1 Megohms.