This simple circuit can work with either 4.5 V or 6 or 9 V if a 1k resistor is added in series with the set of LEDs. The circuit is from an old French publication.
This circuit makes use of an integrated LM2907. The circuit is from an old documentation being...
This sensitive signal follower with an LM386 integrated circuit can be used in both audio and RF...
This transmitter, found in Raytheon documentation from 1957, has a range of a few meters. L1 can...