[DML] Installing a dash-cam -- need electronic design assistance

[Hank <heskin@xxxxxxxxx>]

Ok, so I bought a little gadget called "Vehicle Safeguard" (see:
http://www.gadgetuniverse.com/product_detail.asp?SKU=TC+246) which is a
little digital web-cam type device that you mount in the car.

It arrived today, and it basically does what it promises. On the other hand,
it won't work exactly like I want it to -- I was going to install it
behind the lower grill with 12V power, so whenever the D is "on", it would
be recording.

Well, as it turns out, it has to be manually turned on each time. Not only
that, a "record" button has to be pressed to start and stop recording.

So what I'm looking for is a little device which will:

Upon 12V power up:
1 -momentarily close contact "A" (turn on)
2- wait 10 seconds
3- momentarily close contact "B" (start recording)

then upon 12V powerdown:
4 - momentarily close contact "B" (stop recording)
5 - wait 10 seconds
5. momentarily close contact "A" (turn off)

And "momentary" is about one full second.

This device should operate on +12V, and would need an on-board battery (or
capacitor) to still handle the 12V power down sequence (since the ACC source
power would be gone)

The camera itself runs on +12V and has 3 AAA batteries onboard, so it will
be on 12V ACC power while it is on and recording, and only on battery power
during the powerdown sequence. In fact, this extra device can pull temporary
power off of the camera onboard batteries as well (+4.5V).

I suppose another option is to run 'always on' +12V to the camera, and just
do steps #3 and #4 above (leaving the camera on full time), but that would
mean I'd have to run power and a 'sense wire' as well. I'm not sure which is
easier. And if for some reason the camera gets out of sync with this device,
it will be turning off/on instead of on/off.

So how hard would it be to design such a device?

If someone can design it, I can build it.

If this is too 'off topic' for the DML, please respond to me off-list.
thanks.

-Hank #1619


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