Build this DIY keypad operated switch using cheap off-the-shelf components.
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Keypad Tamper Alarm - Photograph

MORE KEYPAD CIRCUITS


Keypad Tamper
Alarm - Schematic
The Rest of Ron's Circuits Write To Ron More Free-to-Use Circuits Circuit Exchange International


Circuit Board

This is a photograph of the Keypad Tamper Alarm circuit board. It's designed to connect to the Universal Four-Digit Keypad Operated Switch. A few genuine mistakes - made during code entry - will not activate the device. But repeated attempts to find the correct code by trial and error - will cause the keypad to lock-up - and sound the Alarm.

A Photograph Of Ron J's Keypad 
Tamper Alarm - Circuit Board


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Keypad Tamper
Alarm - Schematic
The Rest of Ron's Circuits Write To Ron More Free-to-Use Circuits Circuit Exchange International