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 was obtained from a 2005 Linear Technology application manual. The circuit is...
Small time intervals up o some minutes can be achieved with this circuit. Only incandescent lamps...
This circuit is from a 1977 Radio Shack documentation. It produces a modulated sound of good...