| 摘要 |
A battery powered transmitter circuit has a LED of a continuously cycling microcomputer transmit a beam of a predetermined number of infrared pulses at predetermined time periods to a sensor of a battery powered receiver circuit. Only a clock circuit of each circuit of the same frequency is continuously powered. The two clock circuits are synchronized each time that the sensor senses the predetermined number of infrared pulses. When an object breaks the beam, the sensor causes a count of the object by a microcomputer of the receiver circuit. The receiver microcomputer is inactivated when the sensor does not sense the predetermined number of infrared pulses during one or more cycles of operation of the receiver microcomputer. There is only one count incremented on a count display after the beam is interrupted until the sensor again senses the predetermined number of infrared pulses. |
