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.
We found this circuit in a 1965 publication by General Electric. The zener is 8.2 V x 1 W and the...
This circuit was obtained in an Electronic Engineering of the 90s. The operational amplifiers and...
This circuit is suggested by Texas Instruments in his Optoelectronics Sourcebook. The transistors...