Simple cheap alarm design.

[ptonce]

I happened on your conversation while searching for some alarm info. I think you have what I need help with. I will pick up a new enclosed trailer at the end of the month to haul my bike in. I want to install a simple alarm system. One magnetic contact for a ramp door, one for a side door and a motion/tilt sensor. I want to connect to a siren and possibly a small strobe light. I would need a keyed on/off switch to arm/diarm system. I would run off of a lawn tractor or motorcycle battery in the trailer. It looks like your describing almost exactly that here. I am capable of installing as long as I can get a materials list and diagram to go by. Any help would be appreciated!!! I have a hard time giving up $400~700 for a system.
Thanks in advance

 

[Soundguy]

The diagram has already been posted.

Magnetic alarm switches used to be available thru radio shack.. not sure if they still are.

Switches like mercury switches ( found in older coiled strip thermostats ) work great as tilt switches.

Single pole ( 2 terminals ) ford or generic Key on/off ignition switch will work fine for the SPST switch in the diagram.

Momentary switch can be a push button or 'horn' button type switch.. momentary SPST available in many styles at radio shack.

the relay is also available at radio shack.. etc.

Pin and roller contact and feeler switches are available at radio shack.

soundguy

 

[ptonce]

thanks for the response. Looks like a trip to the shack tonight to see what they have. I'll print the diagram and see if I can get all the material for the end of the month to install.

 

[patrick_g]

thanks for the response. Looks like a trip to the shack tonight to see what they have. I'll print the diagram and see if I can get all the material for the end of the month to install.

Sorry bout the time you will probably waste at Radio Shack which is on its way to becoming exclusively a telephone and toy boutique but I tried two of their stores and they don't stock the mag switches.

You can get the switches from Radioshack.com as well as the relay. The momentary contact switch is cheapest as a simple doorbell switch at Lowe's or other big box store and they are weatherproof.

RadioShack stores used to have all kinds of alarm components including window foil, sirens, mag switches, and on and on but now just seem to stock small little "complete" systems which ae NOT what you need.

If you can't find a cheap siren you can use one of the cheap air horns that come with a small compressor and don't use a tank or just about any other 12 volt DC operated noise maker that doesn't exceed the relays contact ratings or the ability of your battery to provide the current.

An improvement on the circuit I posted would be to include a turn signal flasher to honk the horn. I used a motor driven siren and its effect would be improved with the repetitive interruption so it would wail up and down. Lots of the commercial electronic sirens will do that for you without having to be turned on and off.

Most automotive alarm systems install shops have switches (pin and magnetic) as well as vibration/motion/tilt switches that you should be able to buy a piece at a time.

Make sure your relay contacts are rated to handle the current of your alarm device(es) I paid a couple bucks extra and got a DPDT relay and wired the contacts in parallel to get double the current capability. I got the same realy at the store that is on their web site.

I got the Radio Shack relay part number 275-218. It is double pole double throw 12 volt coil.

Hope this helps... Feel free to ask any questions. The SoundGuy and several others on this site "speak" electronics and will help you.

Pat

 

[ptonce]

Yep! You sure are right Patrck. Went to the shack and found nothing. I can't believe they are still in business. Thanks for the additional info. I will be sure to get back to this thread for help. I'm not shy about being stupid at times.
Thanks

 

[patrick_g]

Yep! You sure are right Patrck. I'm not shy about being stupid at times.
Thanks

Allow me to correct your self appraisal. You are most likely NOT STUPID at all, just perhaps ignorant. Ignorance can be fixed with education, training, and or experience whereas stupidity is forever. We are all ignorant, just possibly on different topics.

Digikey, Mouser, etc are sources of piece parts.

Mouser Electronics is Mouser Electronics - Electronic Component Distributor
Digikey is HTTP://www.digikey.com/

There are a gazillion sources for electronic parts on the web but I can recommend Digikey and Mouser.

Just for grins I took a look on Mouser's site and found a decent relay for $2.03, in stock, plus shipping of course.

Here is the link to that part.

G5LC-14-DC12

This part is in stock (29 units)
There are lots of others if you don't like that one.

Pat

 

[Soundguy]

Hmm.. shack should have still had a small component section in drawrs tucked in back. AFAIK,from a friend that is a RS employee.. the discreet components are still 'force feed' and are restocked on order via computer inventory.. IE.. store has to carry them. Perhaps you just didn't see the small 2 cabinet setup.

Electric single and dual tone alarm sirens are still in stock at rs as well as switches and relay's. the alarm tape and mag sensores are iffy.. and may have to be found ar RSunlimited.. or other supply houses..

* if the store is a kiosk.. or a satelite store.. it won't have the full stock.. which is pretty much now.. cellphones.. etc..

soundguy

 

[ptonce]

Thanks to all for the ongoing information. I will try another shack nearby or the sites shown above.
I have a delay on delivery, so I'm not pressed for time.

 

[patrick_g]

Hmm.. shack should have still had a small component section in drawrs tucked in back. AFAIK,from a friend that is a RS employee.. the discreet components are still 'force feed' and are restocked on order via computer inventory.. IE.. store has to carry them. Perhaps you just didn't see the small 2 cabinet setup.

Electric single and dual tone alarm sirens are still in stock at rs as well as switches and relay's. the alarm tape and mag sensores are iffy.. and may have to be found ar RSunlimited.. or other supply houses..

* if the store is a kiosk.. or a satelite store.. it won't have the full stock.. which is pretty much now.. cellphones.. etc..

soundguy

The RS in Shawnee, OK currently has the 2 stack drawers and is getting two more whether they want it or not. There is still a lot less "stuff" available than 5-10 years ago! They have no pro level alarm supplies which was the case at both stores at Norman, OK (home of OU)

Pat

 

[Soundguy]

I remember when 3/4's of the store was blister packs of goodies.. but that was nearly 20ys ago...

yep.. no real alarm stuff at our local store either..

soundguy