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.
This circuit is from the Radio Electronics magazine of May 1984. With it, it is possible to...
A VCO or voltage-controlled oscillator, which uses only two of the LM3900 amplifiers, is shown in the...
This is one of the many versions of amplifiers with LM386. This was achieved in an old publication (1981). The...