This is a simple tubed mixer from the 50's. The circuit does not include the power supply and has 3 inputs with independent controls. The tubes are double and the inputs are high impedance.
This circuit found in a 1988 documentation consists of a timer or sequential timer controller. The...
This resistance meter circuit was found in the February 1984 issue of Radio Electronics magazine. It is...
We found this circuit on the internet. The components are current, and the time depends on C1...