Rain Detector Circuit

This circuit uses a sensor made of a small piece of etched PC board and a simple SCR circuit to detect rain and sound a buzzer. The SCR could also be used to activate a relay, turn on a lamp, or send a signal to a security system. Part Total Qty. Description Substitutions R111K 1/4 W Resistor R21680 Ohm 1/4 W Resistor D111N4001 Silicon Diode BZ1112V Buzzer S11SPST Switch SCR11C106B1...

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7 Segment LED Counter

This simple counter can be used to count pulses, as the basis for a customer counter (like you see at the doors of some stores), or for anything else that may be counted. The circuit accepts any TTL compatible logic signal, and can be expanded easily. R1-R7----470 Ohm 1/4 Watt Resistor U1------- 74HC90 U2------- 74HC47 Disp---- 7 Seg Common Anode NOTE: All pulses to be counted are to be...

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