I think a alarm is very handy in un-developed countries. Even if your bike is
parked inside the hotel, the hotel-guy's or other guests will still "mess" with it.
Touching and trying all buttons and naturaly, dropping it while trying to sit on
So, I made a highly sophisticated, state-of-the-art alarm from a siren (10 U$)
a 12 volt car-relais (1 U$) a mercury-switch from a heating-thermostat (3
U$), a small switch (0.5 U$) and some wire.
The mercury-switch (a small glass tube with two contacts and a drop of
mercury) makes contact when in upright position. When the bike is on the
side-stand it does not make contact.
The small switch (in a hidden place) switches the system on and off.
If the bike is lifted of the side-stand the mercury-switch makes contact and
powers the relais. The output of the relais goes to the siren and goes back to
the coil-inut, keeping the relais on even if the merucry-switch is disconnected
The only way to switch the siren off, is via the hidden switch.
The system is so simple it can not fail or break. It does not use any batery-
power when "armed" (so it an be on for months). and it can not have "false
alarm" (unless the wind is so strong it throws over the bike).
Only down-side (besides waking up the entire hotel
) is that you have to
switch it off manualy. I am looking for a simple "time-delay-relais" but that is
When I asked radio-shack they had no clue what I was talking about and just
wanted to sell me some batteries or a phone. (progress???)