This circuit was found in a 90s Popular Electronics. It produces a muted tone similar to that produced by a bell. The signal must be applied to an amplifier.
An oscillator whose frequency can be adjusted between 500 Hz and 5 kHz with the use of a...
This circuit of industrial applications has an interesting characteristic: the relay is only...
Any TTL inverter can be used in this circuit. We found it in documentation from the 80s, but it...