Optical potentiometer (CB22159E)

This voltage-controlled potentiometer using an LDR was found in an English documentation. LDR is common and LED of any type.

Wien Bridge Oscillator Lamp Stabilized (CB14039E)
The operating frequency of this oscillator, found in a technical documentation from Texas...
1 W Integrated Amplifier (CB6282E)
Using a component of the era, this 1968 Mallory circuit uses an output transformer whose...
Audio Generator (CB21656E)
Found in Popular Electronics from March 1967, this circuit uses contemporary germanium...