XPost: alt.autos.toyota, rec.autos.tech, alt.autos.honda   
   From: Trueno@AE86.gts   
      
   On Wed, 22 Aug 2007 01:05:54 -0500, Skenny wrote:   
      
   > John S. wrote:   
   >> On Aug 17, 9:36 pm, Hachiroku       wrote:   
   >>   
   >>>And come up with a Cheap-Ass alarm.   
   >>>   
   >>>On the Mazda, I don't want to go to the trouble or expense of installing   
   >>>a real alarm, but I want something.   
   >>>   
   >>>Honking the horn and flashing the flashers would be good enough. I want   
   >>>the horn to 'beep', so a flasher unit and a relay or two would be good.   
   >>>   
   >>>There's two ways to set the thing up:   
   >>>   
   >>>Put something like a key switch under the fender, turn on when leaving,   
   >>>turn off when using the car.   
   >>>   
   >>>Or, a little more sophisticaed: put a switch inside the car. Now, this   
   >>>would mean triggering the 'alarm' when getting into the car, something I   
   >>>don't want to do at 1 AM when I'm leaving on my 'paper route'. So, some   
   >>>kind of delay would be good. I was thinking a capacitor between the hot   
   >>>line and the 1st relay, so the cap charges and when it reaches charged   
   >>>it triggers the relay and starts the flasher.   
   >>   
   >>   
   >>   
   >> All I've read so far are questions about how the car owner would switch   
   >> an unidentified alarm system off and on.  Since you are not buying an   
   >> off-the-shelf alarm what kind of alarm system are you proposing.  And   
   >> more importantly how will the alarm be triggered by a potential   
   >> intruder.   
   >>   
   >>   
   >>   
   >>>But, I need a hint what size cap to use, and how to wire it into the   
   >>>relay so that it charges before setting off the horn, maybe 20 seconds   
   >>>is good.   
   >>>   
   >>>Of course, we could get REAL sophisticated and use the ol' venerable 555   
   >>>timer, but that's more involved than I want to make it.   
   >>>   
   >>>Any ideas?   
   >>   
   >>   
   >>   
   > Why not just have a scr trigger from the interior light? The scr will   
   > switch the horn relay to ground. Door opens, light switch fires SCR, horn   
   > blows until someone turns off the hidden (under dashboard or seat) switch,   
      
   Because this would blow the horn when *I* open the door. I leave at 1AM.   
   But I don't want a delay. A key switch with a cover outside would solve   
   this.   
      
      
   > which breaks the circuit to SCR. You could use a capacitor to give you a   
   > few seconds to leave or enter the car.   
   > After thinking about it, you may have to use a transistor to invert the   
   > signal from the door switch. You could set up your delay with the   
   > capacitor, resistor, to wait 10 or so seconds before firing the   
   > transistor, which would then set the scr. Back in the 70's when the price   
   > of gas was rocketing, people stealing gas from your car at night became a   
   > common occurance. I thought about attaching a small magnetic reed switch   
   > to the gas cap cover that would do the same thing. Just never got around   
   > to doing it. One guy I know wired a 120 volt hot wire to the frame of his   
   > car. I wouldnt recommend doing this though, it could kill someone and give   
   > you a manslaughter charge.   
   > (I know, it shouldnt be against the law to kill a thief, but it is.)   
      
   I like the way your friend thinks. Who cares if the theif gets fried?   
      
   Guess they must have shorted the battery somehow, officer!   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)