Need ideas for "door ajar" sound source

[PetrosA]

I want to wire some kind of audible alarm to the 12V lighting circuit in my van that would let me know when one of the rear doors is open since I can't see them through the solid bulkhead behind me and I keep the lights switched off so they don't kill the battery. I've looked at piezo buzzers, but it seems the 12V ones are all 85 dB and up - no way I'm going to want that in my vehicle . Does anyone have any ideas of what would work for this? I just want to be able to tie it into the circuit that turns on the lights when the doors are open before the off/door/on switch in the cab.

[sacherjj]

There are many piezo sounders that work from 5-15V or so.  I would find that really annoying, but I guess that is the point.  I would imagine a little research and a trip to a junk yard would get you the auto chimes that are normally used, the bing boom type.

[Simon]

is this for an alarm or as a reminder to yourself that the doors are open ?

[Kiriakos-GR]

I just want to be able to tie it into the circuit that turns on the lights when the doors are open before the off/door/on switch in the cab.

I have the solution, one small flasher relay ( like the one that the car has all ready for the direction warning lights ).
Plus one melodic door bell circuit under the drivers chair.

Easy, effective, low cost.  

[Zero999]

I've looked at piezo buzzers, but it seems the 12V ones are all 85 dB and up - no way I'm going to want that in my vehicle .

85dB is often specified at a short distance such as a foot or 30cm. If the buzzer is far enough away from your ears and you don't sit there with it going off, it should'nt damage your hearing. If it's still too loud, cover the sound hole with a piece of tape, then, if it's still too loud,  connect a resistor in series with it.

[PetrosA]

It's just as a reminder that doors are open in back, where I can't see them once I get in (this happens when you load a truck in bad weather, or in a hurry, or get distracted... ) I can see the side doors in the mirrors if it's still daylight out, but the rear doors are completely hidden from my view.

A piezo may be too annoying, especially since it will stay on whenever I have the back or side doors open. I sometimes leave them open for hours while I'm working. All it really needs to do is be loud enough that I hear it when I'm sitting in the drivers seat BEFORE I start driving away It's kind of strange that Ford didn't implement this considering the vehicle is designed to be a cargo van with a bulkhead.

[Vertigo]

why not use an arduino with wav module and make it sexy with custom
sounds?..

[PetrosA]

why not use an arduino with wav module and make it sexy with custom
sounds?..

That might be a little above my competence level at the moment

The arduino... not the sexy custom sounds

Back Door Man by Howlin' Wolf would be my first choice

[Vertigo]

ever since i played portal 2 i have been wanting to stick the voices of those turrets into a small robot
[youtube][/youtube]

[Zero999]

What about using a flashing LED mounted on the dash?

If you don't want to run a cable, you could use a high brightness LED with a horrible colour (something like pink or yellowish green) and aiming it at the rear view mirror so it flashes in your eyes.

You can buy flashing LEDs pretty cheaply but check they're suitable for 12V operation, if not just connect it to a potential divider, to reduce the voltage.

[Kiriakos-GR]

If I open the box that I hide inside my imagination, and looks similar to the Pandora box,
I could advice him to get a Car computer similar with the one that the F16 haves.

Other than common messages like " Pull Up "  " Low altitude "  " Eject Eject " ,
it could also say :
" Back doors open,  kiss and say goodbye to your tools "  

But due the high cost, it is better idea to get an melodic door bell,
and make that Ford to sound like the modern Hyundai does.

[A Hellene]

The cab lights can be powered in two ways:

1. The lights are connected to vehicle's Batt(+) and the cab door switch(es) provide the lights with Batt(-) to turn them ON, or
2. The lights are connected to vehicle's ground, which is Batt(-), and the cab door switch(es) provide the lights with Batt(+), respectively.

Either way, you can use the vehicle's ignition switch in a manner to provide the buzzer with power only when the ignition is ON.

Assuming that the ignition switch is turned ON just before the engine is started, it can be used to provide the buzzer with Batt(+) in the first case, above, with the Buzzer(-) connected to the cab door switch(es) to get Batt(-) when the doors are open. In the second case, the Ign(+) line can be inverted using a simple NPN transistor inverter to provide the buzzer with Batt(-) when the ignition switch is ON, while the buzzer will take Batt(+) directly from the cab door switch(es) when the doors are open.

This way, the buzzer will be on only when the cab doors are open AND the ignition switch is on.


-George

[PetrosA]

Some excellent ideas! In a month, when I get back from Polska and ?? I'm going to implement a mix of them. Thanks!

[Uncle Vernon]

I want to wire some kind of audible alarm to the 12V lighting circuit in my van ..................... I've looked at piezo buzzers, but it seems the 12V ones are all 85 dB and up - no way I'm going to want that in my vehicle

Most of those 12VDC piezo buzzers can have their sound level set with a series resistor or trimpot to achieve a suitable volume level. 

[Kiriakos-GR]

What happened to the planing about visiting your primary target ?  
Polska become a new destination, that cancels the primary ?  

[PetrosA]

Polonia is the hub en route to our main destination Ellas, which got messed up in my previous post because I tried to use Greek letters

[Vertigo]

how about a simple piezo with an adjustable step down converter
with a trimpot so u can tweek the volume real time?

u can make that with less then 10 parts.

or you could get something that plugs into the cigarette lighter socket and hack that.

[Kiriakos-GR]

Polonia is the hub en route to our main destination Ellas, which got messed up in my previous post because I tried to use Greek letters

Use what ever language you like, but exclude Latin.   
Only this can overload my systems.   

[Psi]

What about forgetting the audible alarm and just wire it up to the vans hazard lights.
So whenever the rear door is open the hazards are flashing.

You're never going to miss noticing that as it flashes all 4 external lights, both dash turning lights, and has the click click sound as well.
It would also be a nice safety feature too, so you're visible when getting stuff out of the back.

Actually, i see you keep the rear lights off so they don't flatten your battery. I take it that you want to be able to leave the rear door open for long periods?
In that case that idea isn't going to work so well. Maybe you could use a relay, so the hazards are only connected to the rear door when the ignition is on?