This is a simple - easy to build - cmos 4081 based 4-Digit Alarm Control Keypad. Pressing a single key will energize the relay. Entering the Four-Digit code of your choice will de-energize it.
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Enhanced 4-Digit Alarm Keypad - Photograph

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Circuit Board

This is a photograph of the Cmos 4081 based Enhanced 4-Digit Alarm Keypad. Pressing a single key will energize the relay. Entering the Four-Digit code of your choice will de-energize it. Although it's described as an alarm control keypad - it will have other applications.


A Photograph Of Ron J's 
Enhanced 4-Digit Alarm 
Keypad - Circuit Board


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Schematic
Diagram
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