This photocell looks to be a specialist component and the moulded screw top cap is typical of early 1930s practice. The anode encircles the envelope and has a rectangular window cut into it to allow light in. Running vertically down this window are three fine wires. The cold cathode is semi-circular. The separation of the electrode by placing the anode connection at the top cap could suggest a very high impedance device of operation at elevated Voltages.

The side window envelope is 40 mm in diameter and is 120 mm tall.

This exhibit was last updated on 07 January 2007