door alarm kit

hi

you'll have to forgive my ignorance here but it has been a long time since i
did my gcse in electronics nearly 20 years in fact so i've forgoten alot of
it, but i have a question.

i've had in my work place a large number of computers inside of wooden
cages, unfortunatly these boxes are poorly constructed and it has become
apparent that with some shaking of the door the locks pop out of their
sockets. this has lead to a few people trying to steal the pc's.

what i'd like to do is make a key armed alarm set-up with a led to show its
armed, and a microswitch to put on the door to set it off when the doors
open.

like i said it has been a very long time since i did this last, and although
i can still do the basics like solder, i really havn't cant remember much on
the design.

can anyone advise what i should get and how to construct it, i would prefer
to remeber and construct it myself but unfortunatly i have to get this
fitted sooner rather than later.

many thanks in advance

diesel

 

why not just get some us the devices used for home alarm systems that
monitor doors or windows - a lot easier and possibly even easier than trying
to make your own. Losts on the the internet


--
Dan Hollands
1120 S Creek Dr
Webster NY 14580
585-872-2606

www.QuickScoreRace.com

 

yeah i've looked at them but as these cages also contain money in them i'd
prefer to have something that needs to be disarmed. rather than have the
batteries ripped out. most of the systems i've seen like that could be
disarmed fairly quickly if you know what your doing.

also and this is the bigger aspect, the cost, we have 24 of these cases and
we'd like to keep the cost down.

also profile, with the system i'd like to install i'd like only the key
switch and led to be seen, these cases have grills and lights inside so
cables can be tacked to the edges and be hidden where as the units your
refering to would be on display.

diesel

 

VCC
+
|
|
o arm/enable keyswitch
'\ (A)
\
o \
| LED ___
o------->|----|___|-.
| |
| |
| ===
| GND
|
o---------------------.
| |
| |
| '----. |
| | | |
| | | |
'_ | o o
) | '\ '\
) | \ \
._) | o \ o \
| | | |
| | | |
o-----' | |
| | |
| | |
| o (B) | ,---. alarm
|=|> | | X | device
| o | '---'
| | |
| | |
| | |
=== === ===
GND GND GND
(created by AACircuit v1.28 beta 10/06/04 www.tech-chat.de)


A double pole, single throw relay and a switch or two. Close master
keyswitch (A) to arm the system. If switch (B) shuts, the relay
energizes, shutting the two contact pairs. One pair of contacts sets off
the alarm and the other acts as a sustaining path to ground so that the
alarm continues even after switch (B) is open.

(B) would be a "normally closed" microswitch that's held open when the
door is shut against it. Open the door, switch closes, alarm goes off.

 

Why don't you fix the doors?

--DF

 

long story, awaiting joiners to return in about 2 weeks

tbh i'd like an alarm on these units even after the doors are fixed.

 

You didn't say that. If you're trying to protect cash, you need something
much more secure than a poorly constructed wooden box that people can open
by just jostling it.

Either get proper boxes, or station a 24 hr. armed guard.

In other words, electronics won't solve your fundamental problem for you.

Good Luck!
Rich

 

http://www.google.com/search?hl=en&q="door+alarm"&btnG=Google+Search

Good Luck!
Rich