Relay for Car Alarm Siren Output

shortcircuit161 wrote: Question? If each siren is working fine with one direct to the alarm and 2 aren't working, have you confirmed your grounds are solid for both and good ground to the alarm brain? If you take the positive and negative wires from both sirens and test them together direct to the battery or another known good 12v and ground location, do the sirens work fine? If the alarm brain is capable of running one siren (which draws about 1-2 amps), it should be able to push a relay (that only draws about 300mA) to then make both sirens work. I have 3 sirens in my car (2 under the hood and 1 hidden inside) all running off a relay attached to the siren wire and work flawlessly. Did I miss anything?

Well my dear shortcircuit, I've done that, I mean, hooking the 2 sirens to 12 v and they work just fine. But your opinion made me think that probably the alarm ain't properly grounded. Gotta check on that.

lurch228 wrote: Best that I can figure this should work. With a 100ohm resistor on the base. npn KSC5402DTTU link below. npn

Thanks lurch, you have been a great help. I will check this transistor and also check for availability on my nearest electronics store. Sometimes I hate to wait for them to arrive on the mail.

shortcircuit161 wrote: Question? If each siren is working fine with one direct to the alarm and 2 aren't working, have you confirmed your grounds are solid for both and good ground to the alarm brain? If you take the positive and negative wires from both sirens and test them together direct to the battery or another known good 12v and ground location, do the sirens work fine? If the alarm brain is capable of running one siren (which draws about 1-2 amps), it should be able to push a relay (that only draws about 300mA) to then make both sirens work. I have 3 sirens in my car (2 under the hood and 1 hidden inside) all running off a relay attached to the siren wire and work flawlessly. Did I miss anything?

The issue were trying to solve is voltage and amps to power two sirens with chirps not a full alarm problem, Wether it be a problem with a weak output from the brain for the chirp circuit or the 514n's drawing to many amps. I have the same setup with 514t sirens both under hood wired in parallel, so it should work as mine chirps, The only issue I have is the sirens go out of phase as the cycle through the 6 tones.

Same with my setup. I have a 514T and an omega Psyren and they both sound like multiple cars going off when fully triggered. But I never have a problem with the arm chirp. All 3 chirp (inside and out) at the same time when armed. It just doesn't seem correct. No one should have to use other electronics to run 2 sirens. Either the brain itself should supply enough amperage or a relay will help do it.   That's why I suggested a bad ground. I've had bad grounds and they do some funky things.

shortcircuit161 wrote: Same with my setup. I have a 514T and an omega Psyren and they both sound like multiple cars going off when fully triggered. But I never have a problem with the arm chirp. All 3 chirp (inside and out) at the same time when armed. It just doesn't seem correct. No one should have to use other electronics to run 2 sirens. Either the brain itself should supply enough amperage or a relay will help do it.   That's why I suggested a bad ground. I've had bad grounds and they do some funky things.

You got a point there, shortcircuit, I'ma gonna check that there ground on my alarm brain to see what's what.

Did you run the grounds from the sirens to the same ground point as the brain in side? That's how I wired mine to eliminate any underhood corrosion problems. People like too wire the ground to the siren base and I think that is not the right way to do it.

Well actually just the front siren is wired like that. The other one is wired to chassis ground not on the base but to a wire I hooked up.

100% with what Lurch says about grounding, grounding the siren on it's mounting screw? In the engine bay? Both no nos! NOTHING should be grounded through a self tapping screw. Star grounding (to the same point) is better practise electrically.