Photoconductive Cell Typical Applications
Why Use Photocells?
Photocells can provide a very economic and technically superior solution for many applications where the presence or absence of light is sensed
(digital operation) or where the intensity of light needs to be measured (analog operation). Their general characteristics and features can be
summarized as follows:
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Lowest cost available and near-IR photo detector
Available in low cost plastic encapsulated packages as well as hermetic packages (TO-46, TO-5, TO-8)
Responsive to both very low light levels (moonlight) and to very high light levels (direct sunlight)
Wide dynamic range: resistance changes of several orders of magnitude between "light" and "no light"
Low noise distortion
Maximum operating voltages of 50 to 400 volts are suitable for operation on 120/240 VAC
Available in center tap dual cell configurations as well as specially selected resistance ranges for special applications
Easy to use in DC or AC circuits - they are a light variable resistor and hence symmetrical with respect to AC waveforms
Usable with almost any visible or near infrared light source such as LEDS; neon; fluorescent, incandescent bulbs, lasers; flame sources;
sunlight; etc
Available in a wide range of resistance values
Applications
Photoconductive cells are used in many different types of circuits and applications.
Analog Applications
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Camera Exposure Control
Auto Slide Focus - dual cell
Photocopy Machines - density of toner
Colorimetric Test Equipment
Densitometer
Electronic Scales - dual cell
Automatic Gain Control - modulated light source
Automated Rear View Mirror
Digital Applications
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Automatic Headlight Dimmer
Night Light Control
Oil Burner Flame Out
Street Light Control
Absence / Presence (beam breaker)
Position Sensor
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PERKINELMER [ PERKINELMER OPTOELECTRONICS ]
