This conventional 4 channel circuit with the 4017 and 555 was found in the November 1991 Radio Electronics magazine. The potentiometer can be 47k and it controls the speed of the effect.
This repellent operates with frequencies from 30 to 45 kHz, serving for insects and rodents. The...
This circuit is from a publication from the 70s. The original text was kept. The medium...
We found this circuit in an old American publication. The transistors can be BC558 and diode 1N34....