Hey guys. Stumbled across this forum after some long searching for what I need.
Here's the deal. I have vehicle security systems that will allow negative inputs to be able to arm and disarm them. This comes in handy with the Ford vehicles since they have a keypad on the door. You can hit 7 and 9 to lock the doors and hit your five digit code to unlock the doors. I use the motor lock and unlock wires to arm and disarm the alarm system. The problem is that these are positive outputs and my alarm needs negative inputs. On MOST vehicles I can use a simple pair of relays to flip the positive from the locks to be a negative the alarm can see. A problem arises when I do certain vehicles like say the 04 to 08 F150s. The positive pulse from the lock/unlock motor wires is so fast that the relays don't have much time to respond and put out either a full ground output or a long enough output. I need it to be about a second or longer.
To correct this I have been using pulse timer relays from either Code Alarm or Directed Electronics. The problem is that I need to use two of them and these guys are about $15.00 apiece. I am using them more and more and my distributors inventory can't keep up with my demand. I would like to make a circuit that I can use that will keep cost down as well as allow me to have them in inventory when I do these vehicles. I do alot of them!!!
Basically I'm needing a circuit that will take the 12 volts positive input from the lock wire and then flip it to 12 volts negative for about say 2 seconds to be safe.
From my reading around I have seen people say you could use a capacitor to make the relay stay on longer but I have never done anything like that.
Here's the deal. I have vehicle security systems that will allow negative inputs to be able to arm and disarm them. This comes in handy with the Ford vehicles since they have a keypad on the door. You can hit 7 and 9 to lock the doors and hit your five digit code to unlock the doors. I use the motor lock and unlock wires to arm and disarm the alarm system. The problem is that these are positive outputs and my alarm needs negative inputs. On MOST vehicles I can use a simple pair of relays to flip the positive from the locks to be a negative the alarm can see. A problem arises when I do certain vehicles like say the 04 to 08 F150s. The positive pulse from the lock/unlock motor wires is so fast that the relays don't have much time to respond and put out either a full ground output or a long enough output. I need it to be about a second or longer.
To correct this I have been using pulse timer relays from either Code Alarm or Directed Electronics. The problem is that I need to use two of them and these guys are about $15.00 apiece. I am using them more and more and my distributors inventory can't keep up with my demand. I would like to make a circuit that I can use that will keep cost down as well as allow me to have them in inventory when I do these vehicles. I do alot of them!!!
Basically I'm needing a circuit that will take the 12 volts positive input from the lock wire and then flip it to 12 volts negative for about say 2 seconds to be safe.
From my reading around I have seen people say you could use a capacitor to make the relay stay on longer but I have never done anything like that.