I needed a small PCB for upcoming projects where a Low Frequency Oscillator will be required. I also had a tube of NOS CA3080 OTA IC's. This low parts count board fills the bill.

It has CV inputs for modulation as well as a trimmer to set initial frequency. Square output is about 20V P/P and triangle about 6V; this board is designed to drop into a "motherboard" PCB for buffering and adjusting output gain, waveform transitioning, PWM, and so on.

Inputs are 12V, -12V and Ground, but anything 10V - 15V bipolar will work fine.

Input and output pins are on 100mil vertical edge pins.

I used through hole parts; a dual version with SMD components and an LM13700 OTA may be coming next.

When you build this PCB, take care when soldering the .1uF bypass capacitors. The caps are very small thru-hole parts and it's possible to short ground and a power rail if you aren't careful while soldering.

If your power supply is decent the board will work fine without the bypass caps, so you might consider leaving them off.

Also there are options to add additional modulation sources besides the "CV IN" pin.

The OTA IC, CA3080, is no longer manufactured, but I had no trouble finding NOS parts on Ebay.

You can read more about this project in the blog post: https://audiodiwhy.blogspot.com/2025/06/lfo-mini-small-and-simple-ca3080.html

Happy building!