This circuit was found in an Australian publication from 1991. It is a transmitter that transmits a signal when it detects moisture. The range is on the order of a few tens of meters.
This circuit can be installed inside a toy space gun to produce a “Phaser” effect. The circuit is from...
This circuit was found in a 1988 publication. The circuit is an alarm with interrupt sensors that...
The frequency in this circuit is adjusted by P1 and given by C1. Short pulses, as the ones...