This wired control circuit serves both volume and balance between channels. We found it in Radio Electronics magazine from August 1968. Transistors are common general-purpose types
This simple photometer circuit uses an LDR as a sensor and the indicator is a sensitive...
This circuit generates sinusoidal signals between 300 and 3000 Hz. We find a 303 Circuits from the 90's....
This oscillator uses germanium transistor avaialble in 1958 when the project was published....