This two-transistor circuit is from a December 1964 Radio Electronics. Modern transistors can be tested. The headphone must be high impedance or crystal with a 2k2 resistor in parallel.
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...