We found this circuit generates signals from 200 Hz to 62 kHz and can be used to repel mosquitoes and mosquitoes. The circuit can be powered from 2 small batteries to 9 V battery.
The frequency of this small transmitter, from a 1978 foreign publication, depends on the crystal. The...
This circuit from an old Motorola manual uses an integrated circuit that is no longer easily...
This circuit with RIAA equalization is from 1985 US documentation. The circuit has a flat response...