I bought a different style of ultrasonic pest repeller designed to be used outside to frighten foxes, cats, badgers and other animals which can detect higher frequencies outside of our hearing range. In comparison, the last set of ultrasonic pest repellers I bought were cheaper and thus didn’t have frequency control built into them which I realised after buying that I would need if I wanted to decrease the frequency.

The plastic enclosure the circuit board was housed in was really sturdy and didn’t have any obvious ways to open the back up with out breaking it so I decided saw through the seam where it looks like different panels had been joined together. The aim was to take care making sure to not saw through any of the delicate parts held inside the case.

Once the case was opened I identified the potentiometer controlling the frequency of the oscillator and replaced it with one of higher resistance meaning the frequency would be decreased hopefully into audible range. With the resistance at its maximum with the new potentiometer soldered in the oscillator was just about audible as a really high pitched pulsating triangle wave with clicks spaced evenly apart. I feel this sound doesn’t particularly fit with the general sonic aesthetic I am looking for.

The conclusion I reached is that I want to build my own oscillators incorporating the sensors on the ultrasonic repeller circuit board as a trigger, effectively replacing the inbuilt oscillator I dislike with my own. This would mean I have more control over the pitch of the oscillator and further my interest and exploration into analog audio electronics, influenced by Peter Vogel and Eirik Brandal.