This damped oscillator that mimics the sound of a gong was found in 90s American documentation. The circuit signal must be applied to an external amplifier.
This light sensor shield, with operational and TTL compatible output or microcontroller was found...
This circuit is from a 1980s Motorola documentation. The circuit can be made with modern...
The number of pulses produced by this circuit depends on the switch pressed. The circuit is from...