This circuit is from a Hands-On Electronics from the 90s. The integrated amplifiers used are well known. The range is a few tens of meters depending on the resistance of the cables.
In the figure we have a high input impedance stage with a general purpose PNP transistor. An NPN transistor...
This circuit makes na incandescent lamp flash fast producing the stroboscopic effect. The speed is...
This circuit was obtained in a 1969 Mullard manual. The transistors are from that time. The input...