PHOTOELECTRIC DETECTORS 



These cells are clearly of value in 'on or off' relay applications where 

 the light flux may be focused on the cell. Their small size makes them 

 particularly suitable for use in portable equipment, although their tempera- 

 ture characteristics may be a disadvantage. Their excellent high-frequency 



< 



E 



^^ 



volts 



Figure 28.53 Operating characteristics of the Mullard 0CP71 



phototransistor 



T junction »C 



Figure 28.54 The effect of ambient temperature in the output of the Mullard 



OCP71 phototransistor 



response is valuable in modulated light systems, or for high-speed counting, 

 especially where an infra-red sensitivity is required. 

 The 0CP71, made by Mullard Ltd., is a phototransistor of ihQp-n-p alloy 



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