3 replies to this topic

[LukeH]

I going to upgrade my headlight warning buzzer to a new gong from a bmw (laugh at me if you want). It produces a sound by grounding T2 and I want it to only activate when the headlights are on and the door opens.

Does this circuit look OK? Should I add a diode somewhere and if so what value?


Thanks Luke

Edited by LukeH, 01 November 2014 - 09:49 PM.

[Dan]

The relay is probably redundant, but yes you should use a diode to block current from the interior light that will find a ground through all the sidelights. Unless you are either using a new twin terminal door switch and not joining the interior lamp circuit, or unless the gong has one internally. It may well do if it's designed for this use, especially as it has a separate ground of its own for the electronics. Do you have any information about the gong unit?

Edited by Dan, 02 November 2014 - 08:01 AM.

[LukeH]

The only detail I have managed to find so far is this

http://www.unofficia...n/e36_gong.html

[LukeH]

I tested on a breadboard just having the gong wired without the relay and I added a diode to a switch connected on T2 to simulate the door switch. It worked but only with the cathode towards the switch. Does that sound right?