Found in 90s Popular Electronics, this circuit produces a modulated infrared beam for a remote phone whose circuit is shown right after it. Infrared LEDs are common.
This high-gain circuit uses junction FETs (JFETs) and must be powered by somewhat high voltages. The...
This circuit counts 1 per second, displaying the value in binary. The circuit is TTL and must be...
Critical components of this project are the Geiger tube and the 300V battery. The battery can be...