on or off single pulse

I want to achieve single pulse every time I turn circuit on or turn it off. This will be used to "push" mode button on LCD screen whenever car goes into reverse.

Any idea on how to do that?

You could possibly do it with an time delay relay and an off delay relay.

The on delay relay would trigger for a programmable time every time it is powered (no actual delay).  The off delay would trigger every time it loses power (no actual delay here either).  The PAC TR7 or the DEI version may be able to do this, just keep in mind you'll need two.

The other option would be a custom circuit.

2 of those will be $$$

Is there cheaper solution? I bet it's pretty simple circuit to build. It just need to be designed :)

About $50 or so, not all that bad when compared to how much time it would take you to design, purchase, and build a custom  circuit.

If it were me, I would design it around a programmable microcontroller.  It would be a pretty simple circuit - a basic 5vdc power supply, the chip, a transistorized input for the reverse signal and a transistorized output to drive a relay to push the mode button.

The programming would take 3-4 hours to write and debug.  The hardware would cost ~$20.  Assembly and testing would be another 1 - 2 hours.  In the end, you would save $30 but lose 4-6 hours of your time.

If you could find an edge triggering counter or flip flop you could drive a D flip flop set up in toggle mode.  However, to work all the bugs out in a system like that and to make sure it is always "aligned" would be problematic.

Well. I had to pay extra $50 for LCD monitor that has automatic switching feature (when it senses AV) to begin with.

Now it's more about hobby then a job, so making something to work is fun. If it's cheap - even better. It's all learning expierence, so..

I wonder if something with relay and capacitors can be rigged to send pulse using capacitor discharge?

Hm. I found "undocumented" features of this device:

http://www.pac-audio.com/instructions/TR7bonus2.pdf

Seems like "Constant on/off - delayed pulsed output 2" is what I need.

Does it mean 1 unit will do it for me?