Frequency meter (CB7383E)

Found in a Popular Electronics from the 90s, this circuit reaches 100 kHz and battery power is recommended.

| Clique na imagem para ampliar |

Integrator (CB14104E)
This circuit can be implemented with other operational amplifiers. The formulas for calculating the...
Antique Mini Transistor Amplifier (CB11872E)
This circuit is from a 1953 publication, consisting of an AM radio with 3 germanium transistors that,...
Thermostat Without Relay (CB18013E)
The sensor of this circuit is a common silicon diode and it directly drives a small cooler with a...