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Homemade electronics Stuff old and new
Fake Alarm Box, LED blinker, Keypad push ON/OFF

Get an old used alarm panel with keypad, remove the standard internal electronic board, add this circuit and a 3.6V lipo battery.
Push one button for blink, and another button for off.
This way you fool stupid people to think you got a real alarm unit installed, so they go some where else and brake in.

You can not drill a hole in the alarm panel and install a normal on/off switch, it will look very bad and also reveal you got a fake unit.
so you need to use the keyboard as input, to get the LED to blink and stop.
This circuit do exactly that, The schematic is very simple, and draw almost zero standby current when it is not blinking.
so you just leave the battery connected all the time.
use a hi-bright LED and change the 220 ohm resistor to highest possible value, this way you use as little as possible current, and battery last longer.
You can use values from 220 ohm to 2k2 depending on the LED. Use a RED LED, they lit up very powerfull at lowest possible voltage and current.
remember to turn it off while at home, so you use no more battery.
The 100k and 470nF set the blinker speed, adjust for a speed you like the best.

A fake alarm panel installed

Thomas Scherrer OZ2CPU 2013