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[MOVED] IC setup that only switches twice, Need Help

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Newbie level 3
Feb 21, 2013
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Hello all,

I'm new to these forums and plan on looking around and soaking up a wealth of information but first things first.

Background: I have recently purchased a Head unit (deck) for my car that has navigation and other fancy features. I can only access the nav and other features when the vehicle is in park. The radio is a Pioneer App Radio 2. Normally this is a simple solution by grounding out the parking break wire, or even a simply relay. The problem is that Pioneer got a little smarter and in order to access the nav and other features, I must put the car in park, release the parking brake, and put the car in park again for the second time. by doing this you are essentially, closing the circuit, opening the circuit, then closing the circuit again. I have wired in a temporary momentary push button that is normally closed by putting the parking brake wire from the head unit on one terminal, and a ground lead on the other. I can access the radio features by pressing the momentary push button twice.

Concept: I would like to be able to make an integrated circuit (both as a hobby and a learning experience, I know the momentary switch is the easiest solution) that could achieve this two stage switch. I have looked into the 555 timers, binary counters, and flip-flops, but have yet to be able to figure out a way to make them switch a certain amount of times on their own. Any advice or solution help will be gratefully appreciated.

Can a moderator please move this thread to the "Hobby Circuits and Small Projects Problems" thread. apparently I'm still inefficient with a track-pad.
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It sounds as though you are looking for a 'count to N and halt'.

A 4017 (1-through-10 sequencer) might do the job. You can tap off any or all of the 10 output pins. Skip one or two pins, when you need a delay.

An alternate IC is the 4028 (BCD to decimal decoder, or 'select 1 of 10'). It would need input from a counter circuit to make it work.

This might be a very beginner level question but the power wire that will be coming into the module I'm constructing for this circuit is 12v since the car is 12v. How would I go about reducing this down so comply with the hardware in the circuit?

The 4017 IC accepts a 3 to 15V supply.

The 12V system in an automobile normally does not go above 15V. Hence the IC should be okay if powered from the vehicle (unless your alternator were to get out of adjustment and rise over 15V).

You will have to make sure the incoming signal has sufficient swing up and down, to activate the 4017 input.

As for the 4017 outputs, they can only handle a certain amount of mA in or out. If this is not great enough to activate your other devices, you may need to boost the power with an intervening relay or transistor.

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