This decorative circuit was found in the July 1994 issue of Electronics Now magazine. It makes LEDs blink in a face-shaped allegory. The frequencies are given by the capacitors in the oscillators.
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....