You need to run a big #10 or #8 from the battery to the compressor. Use a relay to turn it on and off and run the power supply for the relay off a key on switch. That way if you forget to turn it off the compressor will not drain your battery.
For the horns, any 12v power supply will work, they dont draw anything unless operating so... I have mine on a constant supply so I can just walk up and scare the hell out of people.
i got you, but I could run a straight wire to the battery with the horn, and at the same time have a different wire with a relay for the compressor., and what about grounds? Im not very electricity inclined. Just attach to the frame rail? or do I attach to the negative battery hole?
Just ground to the frame for both the horns and the compressor. You could run the wire for the horns off the battery, but then you have to go from the Battery thru the firewall to the button and back out the fire wall. If you find a constant hot in the cab, then you run from that, to the button, and out the fire wall, only one trip thru the fire wall!!! Fuse at the battery for the compressor, and one in the cab for the horns. Horn fuse should be around a 10amp, compressor 30amp. Get a 30amp relay from napa...
Ok im gonna do that, last question how does a relay work? do I have to manualy cut off the compressor or does it do that automatically?
O and my compressor came with a 30 amp inline fuse, but the horn didnt should I buy one?
You could but the solonoid on the train horn does not need near as large of a power supply. Heres my advice. Run #8 or #10 to the compressor depending on compressor size. If you are runnning a small 1 or 2 gallon airtank you can purchase a pressure switch which will turn the compressor off once it reaches the right pressure. To activate the horn you will have to run power from a switch inside the cab to the solonoid.
Here is what you should have... and bear with me here...
Battery to Relay to pressure switch (should have come with the compressor and goes in the tank. It opens when the pressure gets to 200psi and closes when it gets to 170) to compressor. Then a ground to the frame.
From your relay you should have a key on wire into the cab to a switch and then a ground to the switch.
Your switch in the cab doesnt supply power to the compressor, only closes the relay allowing power to go to the pressure switch. When the air supply is low the pressure switch closes and supplys power to the compressor (turning it on of course). Then when the pressure is up to max the pressure switch opens and power is cut to the compressor (turning it off of course...LOL)
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