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warning horn not working. Why so expensive?

R

RichardInDorset

Member
So what magical components are inside the warning horn module that make it cost $100?

The piezo buzzer is a $2 component from any electronics supplier.

The OMC one has 3 terminals. Ground, +12v feed from the ignition key and an alarm signal.

My understanding is that it should emit a single fading beep when +12v appears on the + terminal and it should emit a constant tone when the alarm input goes to ground.

The VRO has it's own electronics to make the pulses for oil low and no oil signals, but just wagling the alarm signal wire between +12v and ground.


I am thinking a 12v piezo wired between +12v and the alarm signal would work just as well. I can add a test button if needs be.


EDIT:

Had a look inside the OMC sounder. The piezo has sperated. The piezo crystal is supposed to be bonded to the metal plate.

I got a very loud sounder to replace it for £1.50. (top of pic)
20200707_115657 (Medium).jpg
 
Last edited:
Looks like the factory alarm module also pulls up the alarm wire to +12v because if you take the module out, the motor won't start!

So need to add a relay or transistor to switch on the sounder when the alarm signal goes low instead of using the alarm wire as a 0v supply to the piezo.
 
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