|Weird Electronic Gadget
||[Feb. 13th, 2008|10:31 am]
A few years ago when I bought my car the dealer left this on my keyring. A friend, who had also bought a car from there, said it was part of the dealership's key tracking system. He thought that the dealership had a board where these jacks were plugged in and when a salesman needed the keys to a car he would punch in his name and password then pull the keys he needed.
When I take the metal clip off I can see 2 wires inside of it. I haven't wanted to tear it down any further yet.
My question is, have any of you ever seen anything like this or have any idea what it is specifically?
2008-02-13 09:35 pm (UTC)
Seems to me like a LED hooked up to the plug. I would guess that the 'logic' would be in the board that holds the sockets for these plugs. Put some current on the socket and the LED will light up -- perhaps indeed a pegboard that makes the right set of keys light up?
2008-02-18 10:56 am (UTC)
I've seen something similar
I've seen similar jackplugs on keyrings in the UK, but a long time ago. IIRC in the late eighties/early nineties there was an after-market car alarm/imobiliser that used a jackplug for it's key.
There were some home-brew versions described in hobby magazines that used CR networks in the plug to provide a characteristic for the "lock" to measure, but the COTS version was at about the same time that smt serial eeproms became available. If it WAS a car asecurity system then it could be that the previous owner had it on a previous car and the "key" found it's way onto that bunch when he sold your car.
That said I've spent a while working in comunal buildings and a good key tracking system sounds useful... might have to get to work on that;-)
It might have just been a method of quickly noting which keys were in or not. If you've got a board full of sockets and there's current going to them, then A) the LED would light up, and B) the plug in the socket would complete a circuit which, assuming it was connected to a computer, would be able to tell which keys were plugged into the board and which ones were out.
I used a multimeter on diode to stimulate the 3 contacts but got no response. I don't think there were any shorts between any of the contacts either.
I recently attempted to take it apart but found that one end is crimped down tight and the red capped end I was reluctant to pry at too much because it might break the lens.
I think I'm going to give the dealer a call and try and social engineer an answer out of them.
What you should try is to apply current from a battery (try ~3V) to the tip of the jack and the middle band. If nothing happens, reverse polarity and try again. I suspect that the light will light up when there's enough voltage going through it. You my need more than 3V, especially if it's an actual bulb and not an LED. I don't think you can "stimulate" a diode with a multimeter, unless it's putting power into the circuit. Try giving it some juice and see what happens. Your idea of contacting the dealership isn't a bad one, but if you want to try and figure it out yourself...
I'll try a battery when I get home in a week or two. I guess I'm still stuck on the LEDs I had on some of the electronics I worked on in the Army that I could put the multimeter on the diode setting and it would light it up faintly.
If your multimeter had a diode testing function then it might have passed a minute amount of current through the component to test polarity and make sure that it wasn't burned out or otherwise not working. If you just touched the leads of a regular multimeter to it, it probably wouldn't do anything. Hey, for that matter, if you have a stereo with that size jack you might be able to get it to light up just by plugging it into the headphone jack...