This circuit was found in a 70s documentation. The transistor is from that time. L1 has 4 turns of wire 20 in the form of 3/32 inches and L1 has 10 turns of the same wire,
The frequency of the sound emitted by this circuit depends on the light intensity on the sensor....
This circuit is from a thyristor manual from On Semiconductor. It makes use of a PUT and a SCR...
This circuit uses only one NC75Z04 port from ON Semiconductor, but it can be implemented with...