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 simple source with zener regulation is ideal for experimental projects with operational...
This circuit is from a 1977 Signetics manual. BC107 transistors can be replaced with BC547 and...
In the figure we have an old circuit for controlling two low-power lamps. The circuit is from...