RADIOVISOR LIGHT DEPENDANT RESISTOR, 1940's

Light dependant resistor for use in alarm systems or counting in factories.
Resistance of the unit varies with the light shone upon it, so if the light is interrupted the resistance will change.

Your comments:

• I have two of the Radiovisor light-dependent resistors which I staff-purchased from Radiovisor when I worked there - until I
  got Mick Hufflieted and left under a clod.
  
  They're boxed, with the price, 27/6d, printed on the box. Shows how stable prices were in those days. I collect this sort of thing and the pride of my collection is a Fellowphone two-valve Broadcasting Cabinet c. 1920!
  
  Great site BTW.
  .......... Mick Miller, London, 28th of October 2014
  
  
• A question. Light cells were used in transatlantic wire photos and cinema projectors in the '30's. So says Popsci/archives. Put one behind a slotted screen, connect to a relay on a clockwork escapement driving a rudder and you have the beginnings of a low-tech smart bomb. Add another cell at right angles to drive an elevator, add some stub wings and there is the potential to steer a bomb down a searchlight beam. Also magnetic version to drop on iron roofs of factories, locomotives or tanks instead of adjacent fields. How about a metal detecting torpedo,- the Germans had their Oyster sea-mines in 1944-. The technology was available, but did anyone put it all together ? ( - and if they did, who stopped it ?)
  
  Location - Christchurch Dorset UK
  
  
  .......... john bridle, Christchurch Dorset UK, 7th of November 2011
  
  

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