This interesting circuit found in American documentation generates a busy signal, without you having to take the phone off the hook if you do not want to answer. The components used are common.
Factor Q measures the selectivirty of a resonant circuit and also receivers. This circuits cen...
This circuit was suggested by Popular Electronics from the 90s. The circuit is quite simple using...
Found in a 1969 neon lamp publication, this circuit provides two voltages under very-low currents....