Motion Triggered Horns
Essentially what I'm starting with is a driveway wireless alert system (http://imgur.com/a/RgDeG) and a car horn. The car horn is wired to a push button switch. (http://imgur.com/lg7Gbvj)
What I'm trying to do is replace the [S] (switch) with this wireless trigger.
The alarm speaker outputs at a very low voltage, ~0.08v: https://vimeo.com/75827101
The alarm LED's output 1.75v (measured from + on the one LED and - on the other, there are three total, in series)
What would be the best place to tap in to get voltage from to trigger the relay? I think from the previous post I'll need a transistor switch of some sort? This is the part I need help with.
Usage: Tractor pulling hayrack riders over a bridge, I'll place the sensors ahead of the horns so by the time the tractor is at the sensor the hayrack is right at the horns.
Hope I posted in the right spot.