摘要 |
A pager operated control unit has input terminals of the control circuit are connected to the battery terminals of the pager and power is supplied to the pager receiver from the control circuit. Pager generated pulses are detected by the detection of changes in current drawn by the pager receiver. The control unit includes a pair of capacitors which are alternately charged under the control of a flip-flop in response to bursts of pulses generated by a pager receiver. An output relay is operated to one state when the charges on the two capacitors substantially equal, indicating the receipt of a burst of pulses of equal duration, and operated to another state when the capacitors have unequal charges, indicating the receipt of a burst of pulses of unequal duration.
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