This power control for powers up to about 10 W uses wire potentiometers in an arrangement that allows to maintain the impedance. The circuit is from old European documentation.
The two previous circuits show the INA185 a current sensing amplifier in basic applications. This...
This metronome configuration with the 555, quite common was found in a 90s Hands On Electronics. The...
This bidirectional circuit was found in an American documentation from the 80's. The LEDs are...