Function Generator

LM324 Function Generator Project

It all started during a late-night electronics binge when I was a college student struggling with analog circuits labs. Commercial function generators were way out of my budget—hundreds of dollars for something I'd use occasionally to test amplifiers or filters. I scoured old datasheets and forums, and stumbled upon a classic design: a simple waveform generator using just the LM324 quad op-amp.

This circuit has humble roots in educational resources, like MIT's op-amp guides and manufacturer application notes from companies like Onsemi. It's a timeless hobbyist favorite because the LM324 is cheap, widely available, and forgiving for beginners. The magic lies in chaining basic op-amp building blocks: one section acts as a Schmitt trigger oscillator to produce a clean square wave, the next integrates it into a linear triangle wave, and a final integrator approximates a sine wave (with some distortion, but good enough for low-frequency testing).

I breadboarded it first with scavenged parts—resistors, capacitors, a potentiometer for frequency tuning, and a dual power supply. Tweaking the pots while watching waveforms emerge on my cheap oscilloscope was pure joy: square for digital logic tests, triangle for ramp signals, and that quirky sine for audio experiments.