Hi there,

Thanks in advance for any advice you might have.
I’m trying to create a park brake warning buzzer for our Yamaha Viking ATV, which will sound whenever the vehicle is driven with the park brake on.
There’s already a small (P) park brake light on the dash, which illuminates when the park brake is applied. If the vehicle is then driven with the park brake on, this (P) park brake symbol begins to flash. The problem is, it’s a tiny symbol and hard to see, and we constantly get in and out of the vehicle, using the park brake, as we work around the farm.
So if can tap into the dashboard park brake light wiring, I’ll get a steady signal each time the brake is on, and an intermittent signal when the vehicle begins to move - this is the time I’d like to activate a buzzer.
My question then, is if I have a constant power signal (park brake on), how can I trigger a buzzer if this signal then becomes intermittent (vehicle begins to move)...
Thanks again!

 

If you couple the signal via a capacitor to trigger a 555 monostable driving a beeper so the lamp going on causes a beep, you will get one whenever it comes on so first application of the brake will beep and that is ok. Then with each flash you will get a beep too.
Depending on the circuit, you may even get away with just a capacitor connecting to a piezo beeper and a reverse diode across the beeper.

 

Welcome to AAC!
This should work for you:

D1 can be any small-signal silicon diode and M1 can be any 'logic-level' N-channel MOSFET. C1 and R1 values are not critical, but if C1 is reduced then R1 should be increased.
This assumes a piezo type buzzer. If the buzzer is electromagnetic then a reverse-biased diode across it would be needed to suppress back-emf spikes.

 

that is a lot simpler than my 555 idea!

 

Wow thanks for the fantastic advice, I really appreciate it. Looking forward to going through a few less brake pads now...!

Thats some fantastic advice, thanks very much for your help!