+/- pulse to output a full time grounds

I do universal GSM pager systems in cars so when the alarm is triggered, this particular unit texts the vehicle status to the owner of the vehicle via cellphone. The problem is that this unit needs a full time grounds to switch this unit to ON. and when the ground drops, the unit turns off, thats the normal switching operation.

Some alarm systems have a 'ground when armed' wire so its easy to connect to this, but if I have no pulse like the ground when armed wire, I cant switch this GSM pager system on.

Am looking for a way by using relays,either I give it a negative or a positive pulse, I would like an output of grounds when activated and grounds disappears when this circuit is disarmed.

HELP ANYONE?

-------------
I'll be back, so nobody go no where

If the alarm has a siren output, you could hook up a relay to change the polarity of the siren output to - to drive the pager system.  By the way what alarms are you talking about that don't have a ground when aremed output?

-------------
Cause I'm So white and nerdy...
First Class Certi-fried installer

Autowatch 446RIS ones. They dont have a standard sirens but digital speakers so cant actually get a positive or negative from it. The Autowatch 160RLI has ground when armed in the glass sensor so that ok for now but if am using a the RIS, i would like to get info on how to use a relay to produce a ground when armed wire from just a pulse.

thanks

-------------
I'll be back, so nobody go no where

Use a LATCHING Relay.........
Power + or - to Relay will Activate Relay until another + or - is recieved......

U can get them @ most Relay suppliers or E-Bay...
https://cgi.ebay.com/Latching-Relay-DPDT-Dual-Coil-12-Volt_W0QQitemZ6004161280QQcategoryZ11644QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

-------------
MO

Don't Learn from Others Mistakes
You Might Be the One That Knows.

You can build a latching relay. there is a post on this site. incidently that exact post is how I found this forum

-------------

thanks for the reference but isnt there any way I can make a relay myself.?

-------------
I'll be back, so nobody go no where

Ok Yes there is a way to build a latching relay yourself. Many actually. u need a neg output rite? Here ya go. Takes 2 relays but it will work great. 1st relay 87 to ground, lock output from alarm to 85 put a diode in this wire with cathode facing alarm then put another diode from 85 to 30 with a cathode facing 30 then 30 out to you constant neg acc.yes so at the realy you have a wire and a diode hooked rite to the terminals, then 86 to 2nd relay 30 then 2nd relays 87a to 12 volt then 2nd relays 85 to 12volt then 2nd relays 86 to unlock actuator wire to alarm output the actuator wire for the unlock the wire that rests on ground all the time except when unlocked it flips to 12v for a sec. I know it seems confusing but it really will work and if someone does not beleive me then prove me wrong. I use a similar setup and there is no relay config that I cannot figure out. I hope it helps.

What is going to be the control inputs? Do you have two separate pulse signals, one to arm, and another to disarm, or is it a single signal that you're expecting to have it toggle on and off each time the pulse comes in?
You could just wire up an RS flip flop with some CMOS logic gates, instead of relays, since you don't really need drive capability from the circuit's output. Or a J-K flip flop if you want to toggle. Cost of parts would be next to nothing, even if you add some protective circuitry for extra reliability like zener diodes and capacitors.

flip flop diagrams

You dont need aftermarket locks almost all door lock factory or aftermarket at the actuator both wires rest on ground. I built a armed output with 2 relays and 2 diodes cant get cheeper than that if you have been installing for any amount of time you would have extra of these all over. I know I do. Hope this helps anyway.

Thanks a lot guys, didnt know there would be so much help provided in the forum, I would try each one ideas given and get back to you.

thanks a lot (really made my day)

-------------
I'll be back, so nobody go no where