This circuit with three transistors was suggested in a Radio Electronics magazine from February 1963. The transistors are types of the time. Power comes from a 12 V battery.
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....