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.
This simple alarm with latching uses a relay as the main element. The circuit is from a Radio...
The circuit shown in the figure generates pulses of up to 200 V under a current of up to 200 uA...
This circuit is from a 1964 Electronic Design. The sensor is an LDR and the transistors are...