Air Horns

What is the typical resistance of a car horn?

I got this old 12V car horn that I'm trying to connect to a simple switch circuit. One of the horns measure .9 Ohms, the other 1.3. I've been trying to drive it with a bench supply, which goes up to 2A. When I connect the terminals together I hear a click inside the horn but no other sound, and it's clear the horn is supposed to have more power. (up to 5A?) So the question is - does evidence above show that the horn is broken, or I simply don't have enough power for it?

Public Comments

1. I would first test the horn across a 12V car battery to verify the functionality of the horn. If it blows, obviously the bench supply does not have the power needed to blow the horn. Hope this helps. Good Luck!
2. I've never bothered to measure the ohms of resistance, but I can tell you an easy way to test the horn... just take two jumper leads from the car battery posts and tap the terminals on the horn. If it beeps, it's good, if it doesn't beep, it's not good. Test complete.
3. At 0.9 ohms and 12 volts, it will take 13 amps. A car system supplies 14-15 volts when being charged, and at 15 volts, that is 16 amps. but car horns I looked at online draw 3-5 amps, so perhaps there is something wrong with the one you have. .
4. The supply hasn't power enough to drive the horn. Check it in you battery car. The behavior you described is normal when there is no amps enough. Any way remember the horn has an internal contact which switches the coil on and off, so the medium current will be lower than that calculated trough ohmic resistance.
5. The bench supply is not able to deliver the 13.3 amps required by an 0.9 ohm load at 12 volts.