This circuit can keep a set of lamps on for up to 1 minute, time given by C2 and R2 that can be changed. The load depends on the relay. The circuit is old, from 1988 documentation, but totally viable today.
The sensor of this circuit is a 2N3055 transistor from which the housing cover has been removed to...
The figure shows how to generate a 60 Hz clock signal for TTL circuits. The circuit is from Radio...
The circuit shown in the figure can generate signals of good intensity up to a frequency of 30...