With this circuit it is possible to modulate pulses from a pulsating input signal. The PNP transistor can be the BC558 and the power must be supplied with 5 V.
The circuit shown in the figure can be useful in cases where a common telephone extension is used....
This circuit uses two operational amplifiers that admit equivalents. The configuration is from...
This circuit was found in General Electric documentation from 1966. The circuit is suitable for any...