Help using tactile switch instead of rocker(low-high-off), relays, voltage, heated seats

Discussion in 'The Projects Forum' started by chadecoen, Oct 14, 2015.

  1. chadecoen

    Thread Starter New Member

    Oct 14, 2015
    14
    2
    Well, probably by my title you can you can tell I don't have a clue about how to do this. I have googled till I am cross-eyed and have some ideas. My knowledge of what these components do or are even called or what circuits to do what I want are called is very limited, so my searches have been difficult at best.

    I would like to install heated seats in my newer vehicle that the canbus system controls everything. I bought an aftermarket heated seat kit consisting of a heat pad, a relay, and a 3 way rocker switch (Warm-Off-Hot).

    The easy way out would be to install the OEM components and have someone turn on that feature in the computer. 1. Can't find anyone to program the computer. 2. OEM heated seat parts are priced sky high. So no OEM heated seats for me.

    I do like the factory dash switches though. Unfortunately the switches are not real switches, they just signal the canbus to turn on the seats. I have taken apart the OEM switch and found a membrane switch behind the push button and just enough room to install a tactile switch between the PCB and the outer button.

    My thought was to install a tactile button behind the OEM switch (Or figure out a way to use the OEM membrane button) and use it instead of the 3 way rocker switch that came with my aftermarket heaters. I have been advised that a decade counter (4017?) would help bring this to life. So I read a little about how, and I if I read right, I would use the switch as the clock signal? and wire it to reset on the third input from the switch? Makes a little sense to me. BUT, what else? I have read that I will need to debounce the switch but have not figured out how to yet.

    And I will need to bring the vehicles 12v down to acceptable voltage for this circuit and figure out if the output of the decade counter will be enough to trip the relays to turn on the seats. Speaking of 12 volts, I know some of these components are rated for milliamps. How would I know what amps my cars electrical system is putting out?

    Relays? Can I make this low amp circuit trip a 12 volt auto relay? Use micro relays on the board? Use a small relay to trigger the bigger relay that came with the heaters? I thought I read somewhere that an IC could be a relay?

    And of course I want a light to indicate the switch position. Or maybe one LED that can change colors? Orange for low and red for hot? Or two LEDs? Additional amps for them too?

    I was even considering taking apart something that already has this type switch and hodge podge the thing together. Like a high, low, off flashlight switch or a fan switch or something? I am sure I can't the only person to have built this type circuit. Is there a proper name for the set up I am attempting? Maybe I am just calling it all the wrong things so not finding good how-to's?

    Lots a questions, sorry. Going in all sorts of directions not knowing what's best. Any suggestions? Thanks for having me, and thanks for all the info you guys provide!
     
  2. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,516
    1,246
    Your research has served you well. In no paricular order...
    The 4017 is a common part for this kind of rotating or stepping control circuit. It has 10 outputs, so it can step through up to 9 active stages and an off stage. Connecting pins together sets the number of steps in the rotation.
    Red indicators usually are reserved for failure warnings. The seat heaters have 2 or 3 amber LEDs stacked vertically for the steps, or one LED that is off, dim, bright.
    Debouncing the switch is imprant, and easy.
    The 4017 outputs can drive only a few mA, but enough to drive a transisor that drives the relays.
    The 4017, LEDs, switch debouncing, and output relays all can be powered off the vehicle 12 V. Vehicle power is notoriously dirty, so some filtering and protection will be needed, but this is a small increase in the circuit.

    Can you give any information on the aftermarket kit? Web site, photos, user manual, etc.?

    ak
     
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