momentary switches to control shifting

Discussion in 'The Projects Forum' started by hman333, Apr 25, 2006.

  1. hman333

    Thread Starter New Member

    Apr 25, 2006
    2
    0
    ok i am working on making a manumatic shifter using pushbuttons for my jeep. i have 4 momentary switches and 4 LEDs, one for each gear, i want to wire them us so that when i press one the corresponding LED will light up and all the others will go off. how can i do this

    ok so far i know this:
    -there is a power wire that comes into the TCU from the ignition
    -There is power out from the TCU to three solenoids, the first 2 are for gear selection, the third is for the torque converter
    -Gears are selected by the transmission from different combinations of solenoind power
    Gear, Sol1, Sol2
    1st, power, none
    2nd, power, power
    3rd, none, power
    OD, none, none

    i want to be able to flip a switch back and forth to select between auto(normal) and manuel(buttons). when in manuel, i want a button for each gear, so when each button is pressed it will give power to solenoid 1, 2, both or neither one. each button when pressed will also light up the coresponding LED. i also want another togle to lock the torque converter by giving power to solenoid 3

    this is where in stuck
    what would be the best way to wire this whole thing up



    would like it to look something like this
    [​IMG]
     
  2. windoze killa

    AAC Fanatic!

    Feb 23, 2006
    605
    24
    Have you also thought about only having 2 switches, 1 to upshift and one to down shift. You could even have them like th paddles on an F1 car. This wouldn't be anymore complex than what you already have. In fact could be simpler.
     
  3. hman333

    Thread Starter New Member

    Apr 25, 2006
    2
    0
    i had thought about it, but i figured it would be harder to wire up, i dont even know where to begin wiring this up, i know what i need to do , but i just dont know how to do it.

    And i would like to wire this myself, instead of spending alot more for a kit, just need a little help.

    Should i use relays or a controller, anyone have a diagram for this

    thanks
     
  4. windoze killa

    AAC Fanatic!

    Feb 23, 2006
    605
    24
    Does each solenoid have a seperate wire going to it? Can you supply a bit of a circuit of the inputs to the gear box?

    Ignore that. I just read you first post again. I will see what I can do.

    Are these momentary switches? I can see a bit of a problem in switching if you do not add some extra circuitry. You may need some latching circuit if they are momentary.
     
  5. Yuri

    New Member

    Nov 17, 2006
    1
    0
    btt
    This is pretty-much what I want to do to the AW4 transmission in my jeep. A couple differences would be: I'd like to use a 7 segment display to show what gear I'm in, and I'd also only like to have two push-buttons (up shift-down shift).

    This modification can be done very easilly using just a 4-position rotory switch and a diode. But I realy don't want to shift gears with a rotory switch. You can use something along the same lines as that with 4 seperate latching switches, but I really don't like that idea very much.

    I have had previous electronics training, but never really messed with building my own circuits very much. And I also know very little about IC's. But with that in mind, this is the direction I'm heading...

    First, the shifting sequence from the two solenoids isn't binary. In 1st gear solenoid1 is on while 2 is off. 2nd has both on. 3rd has 1 off, 2 on. OD has both off.

    For this to work, I need some kind of up/down counter IC. The push of one momentary switch counts up, the other counts down. If the outputs are binary, than I can run them into a 7 segment display driver to show the gears. But I'd still have to figure out how to get those two solenoids working the right way.

    Am I thinking correctly here? I'm just recently been researching IC's and don't know what route I should take with this...

    btw... Each solenoid would need to output +12v dc when activated. I'll have to check my Jeep's wiring diagrams, but I may be able to tap off a +5v source. If not, I'd have to figure out how to do it with +12v.

    Can someone with experience give me direction, or even just tell me I'm wrong so I can start over?
     
  6. EngineerJoe

    Member

    Nov 4, 2006
    15
    0
    There are lots of options here, which will affect your direction and complexity but some basic sub-circuits would be helpful.
    First sub-circuit - switch debounce is important if you want to step up or down only 1 gear at a time. This is a logic function that can be done rather with a nice three terminal switch where the center tap is tied to ground. There are other methods of debouncing that use timing devices to set up a "true" output for a pre-defined period of time, but I like the first idea best.
    Pick a method depending on the type of switch you use, 2 terminal or 3.

    2nd subcircuit - Up/Down counter - lots of varieties (74191, 74193)

    3rd subcircuit -
    drive OD with a NOR gate Output 0
    drive Solenoid#1 with Output 1
    drive Solenoid#1, and 2 with Output 2
    drive Solenoid#2 with Output 3

    You can isolate solenoids from other drive gates with a forard biased diode between the logic outputs and the input to the sonenoid drive circuitry.

    If you choose a BCD (binary coded decimal) output from your up/down counter, you may want to 3-8 Line decoder/demultiplexer (74138) for individual outputs based on your counter.

    Is this the direction you were thinking of going?
     
  7. dmaxben

    Member

    Oct 27, 2006
    11
    0
    this is exactly what I was looking for!

    Im making the exact same circuit, except its to control the allison transmission in my chevy truck.

    I basically need 5 "steps" in the counter.

    Im going to have one momentary button for "upshift" and another momentary for "downshift".

    Ive attached a picture of the basic counter, centered around a 4510 IC. I assume that counter has the capability of counting both up and down WITHOUT having to reach the 'top' first before going back down? Or do I need a different IC?

    output 1 = 5th gear
    output 2 = 4th gear
    output 3 = 3rd gear
    output 4 = 2nd gear
    output 5 = 1st gear

    I have the outputs 'reversed' because I want the circuit to default to 5th gear when I turn it ON (switch from 'auto' to 'manual' mode].

    Then I can press the "down" momentary button once, go to 4th, again, go to 3rd, push the up button, go to 4th, etc.....

    I attached a circuit of how Im setting it up. Am I going to have to worry about switch debounce? How could I fix that? Does it matter how long I hold the switch? For example, if I hold the 'up' button for a split second longer, is it going to count up twice?

    The 4510 outputs BCD I think, so Im hooking it up to a 4028 BCD to decimal decoder. That will translate the logic from the 4510 to an actual "1" "2" "3" "4" "5", correct??

    I have a hex inverter hooked up to output 1 and output 5, so when I reach 5, It will make it impossible to count 'up' anymore, even if I press the 'up' button. Same thing for output 1, so it wont let me downshift below 1.

    The switches are setup so when I push "up" it will make the clock and up/down inputs go high, making it count up one step. Then when I press the "down" button it only activates the clock (I put a diode in there), making it count down one step.

    Does this make sense? Will it work?

    thanks a ton for all the help anyone can provide...

    Ben
     
  8. dmaxben

    Member

    Oct 27, 2006
    11
    0
    bump? :)

    thanks for any help anyone can give..
     
  9. lightingman

    Senior Member

    Apr 19, 2007
    374
    22
    Hi.The little counter circuit will not work... for just a few reasons.1. you need to add pull down resistors to the clock and direction inputs, as leaving them floating will cause all sorts of problems.Also you will need some switch de-bounce circuits (as you stated) to ensure that only one count is made at each press of the button.Also if the direction is changed at the same time as the clock pulse, it may not change direction until another prees.Please steer clear of TTL for use in a vehicle, CMOS is more tollerant to noise and power fluctuations. If you need any more help... Just let me know.Daniel.
     
  10. dmaxben

    Member

    Oct 27, 2006
    11
    0
    Thanks a ton for that help Daniel.

    I will add pull down resistors to the up/down and clock inputs.

    Im actually not using simple pushbuttons...Im using the factory shifter from a later model year truck that has "upshift" and "downshift" buttons built in. It has two wires coming out of it and when you apply voltage to one wire, a certain resistance is returned on the other wire. When you press "upshift" the resistance changes, and when you push "downshift" the resistance changes again. My friend helped me build a little voltage comparitor to translate the resistances into discrete "up" and "down" outputs. So the up and down outputs are either "1" or "0" from AND gates...so I dont think I will have to worry about switch debounce there?

    How would I get aroudn the problem of having the direction (up/down} change a split second before the clock pulse is given? How would I make some slight delay?

    I have the entire circuit running of L7805 5volt regulators.

    below is a picture of the circuit to translate the shifter signals to "up" or "down" that then goes into the up/down counter

    thanks again for the help.

    Ben
     
  11. lightingman

    Senior Member

    Apr 19, 2007
    374
    22
    Hi.That is a good bit of info.Could I sugest that you do it with a PIC16F628 micrcontroller.It could read the levels from the switches that you have, it can incorperate all the switch de-bounce, any delays that may be required in between changes, sequencing and all in one chip plus the 5 drivers required to interface with the outside world (MOSFET's).If you could send me a description of the required sequence of events, any delays, the value of the switch resistors and how you need to drive the system. I could write you a program stick it in a PIC and get it to you.with a schematic. You could then try it...Considering that the PIC's are now only a few U.S. $, it would be worth doing.Also.. If you need to change any functions, the PIC can be re-prorammed.Daniel.
     
  12. dsm4g63t_chris

    New Member

    Nov 29, 2007
    1
    0
    I know this is an old thread, has anyone had any luck with making a curcuit to sequentialy change gears.
    I have a Eagle Talon (4 speed automatic)
    That uses a on/off sequence to control what gear requested.
    Soleniod A B
    1st gear on on
    2nd off on
    3rd off off
    4th on off

    These solenoids being activated by +12v self grounding.

    I have done some research but im just boggled at this point I was going to use two
    toggle switches and "manually" control them on and off but then I risk shifting into a low gear at high speeds.

    Basically it comes down to Im not intellegent enough to write a diagram that will work.


    Any help is appreciated!
     
Loading...