Listing ID #964106
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Contact SupplierInfrared Light Gate Circuit has is ON/OFF by a transmitter and receiver. This IR light gate describes an infrared light source and detector, which can be used in a wide variety of applications ranging from intruder alarms to automatic garage door openness. When the light beam the infrared source interrupted, the receiver circuit detects this and energizes a relay.
The use of an infrared light source is an obvious choice for this type of application. The circuit described here uses the infrared emitter and photodiode.
For a given range the transmission system should be as efficient as possible and the receiver must have high gain. Such a high gain can be achieved from AC modulated light beam and AC coupled receiver.
Transmitter circuit :
Receiver circuit :
About TBA120 :
The TBA120 is produced by several manufactures and several different versions are available. All of these should function satisfactorily in the receiver circuit. However, in some cases it may be necessary to omit R6 or connect it to ground instead of +V, to obtain the best signal to noise ratio. Care should be taken when alerting R6 not to disturb the relative positions of the receiver and transmitter, as this could give false results.