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Cruise controle converter

Discussion in 'Automotive Electronics' started by kerrmotorsports, Dec 21, 2013.

  1. kerrmotorsports

    kerrmotorsports New Member

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    Yep that worked I built and tested it now I think I'm ready to build a test in real life. Where would you recommend to buy the parts? And anything I should do or know before ordering? And again thank you for all the help
     
  2. crutschow

    crutschow Well-Known Member Most Helpful Member

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    If you're in the USA then there are several such as Digikey or Mouser. In Europe, Farnell is often used.

    Note the package types of all the IC's and other parts you order. You don't want a package type that's difficult to solder to a perf-board. You normally want to use DIP package ICs. I also recommend sockets for the ICs since it makes it much easier to troubleshoot and replace any faulty parts.
     
    Last edited: Dec 28, 2013
  3. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    Breadboarding techniques vary. Although you could breadboard surface mount, it's probably not the job for a beginner.

    Vector is a major player for breadboards. No pads (perf board), pad per hole, strip boards are all different designs.

    I would use machine pin sockets for the IC's in an automotive environment. Connectors that are gold flashed might also be useful. You will probably need a crimping tool.

    There is available a pin like terminal that can make resistors appear separate from the connecting traces that you make underneath with wires. These "Vector T-42" http://www.mouser.com/ProductDetail/Vector/T42-1-C/?qs=RPC3RGMGIuY5byT1Qp55gA== They press into a 0.042 hole with a tool, which has gotten really expensive.

    Wire-wrap wire, is Kynar insulated and I've used it to make the connections on the bottom of the board. It is hard to strip. The dispensers are nice, because it comes with an integral stripper and cutter. 22 AWG bare wire is also helpful.
     
  4. dave

    Dave New Member

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  5. kerrmotorsports

    kerrmotorsports New Member

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    Ok so I ordered the parts and a bread board for the first prototype. Everything should be here early next week.
     
  6. kerrmotorsports

    kerrmotorsports New Member

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    Got the bread board and the parts and built a mock up for testing. I got everything working except the flip flop. Everything I looked up puts the clk high to get it to switch. Also I assumed PRE was set and CLR was reset.
     
  7. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    If your having problems with the power up condition of the FF, you may have to place a Schmidt trigger in the line to the CLK input. Inputs have to have really well-defined edges to work.

    PRE usually set Q to 1. RST usually sets Q to 0. I did not look at the actual datasheet.

    One think is certain, that you need a clean edge.

    If you can, set he clock to a steady state and make sure power up sets the FF as desired.
    CLK is usually EDGE TRIGGERED and they mean it. Sloppy edges won;t work.
     
  8. crutschow

    crutschow Well-Known Member Most Helpful Member

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    Yes, as I noted in my post, the FF switches at the end of the pulse from L3 (ON switch) which is the rising edge of the pulse (the L3 pulse voltage is normally high at steady-state).

    R2 and C1 generate a momentary High signal to the CLR input to reset the FF Q output to the Zero state at power up. The CLR input is asynchronous (insensitive to the clock) and does not need a fast edge since it responds only to the voltage level.

    What problem are you having with the FF?
     
    Last edited: Jan 4, 2014
  9. kerrmotorsports

    kerrmotorsports New Member

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    When I pull CLK to ground and disconnect it, it doesn't activate the FF
     
  10. crutschow

    crutschow Well-Known Member Most Helpful Member

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    Of course it won't. An open circuit is not a logic one at the input to CMOS digital circuits, it's an indeterminate state. That's why I previously said you need to connect all unused CMOS inputs to ground.

    If you add a pull-up resistor to the +V from the clock input, then it will activate the FF when you momentarily ground the clock input. But note that clocking the FF that way will likely introduce bounce in the signal which may clock the FF more then once.

    Edit: Upon reflection, the bounce of the ON switch could also cause multiple clocking of the FF. To prevent this, connect a 50k ohm resistor between the FF /Q output and the D input. Also connect a 10uF capacitor from the D input to ground. This will provide a delay so the FF can't rapidly toggle even with multiple fast clock pulses.

    If switch bounce is a problem with any of the other outputs, let me know. We can add some additional capacitors to prevent that.
     
    Last edited: Jan 5, 2014
  11. kerrmotorsports

    kerrmotorsports New Member

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    So I've built and tested and had it working on bread board. Built it on a circuit board and now for some reason Pin 11 is always pulled to ground
     
  12. crutschow

    crutschow Well-Known Member Most Helpful Member

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    If it worked on the breadboard and not on the circuit board then I think it's likely you have a wiring problem. Double check all connections.

    Pin 11 on what chip?
     
  13. kerrmotorsports

    kerrmotorsports New Member

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    On the lm3914 and even when I go back to the bread board its doing the same thing I tried a couple of chips also
     
  14. crutschow

    crutschow Well-Known Member Most Helpful Member

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    You said you had it working on the breadboard, now it's not? :confused:

    Try separating pins 11, 12, and 13 and see if they are all low (with a 10k resistor connected to V+ attached to each output).
     
  15. kerrmotorsports

    kerrmotorsports New Member

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    I Isolated the pins and its only 11 even with a 10k resistor. If I hook up a potentiometer it works correctly.
     
  16. crutschow

    crutschow Well-Known Member Most Helpful Member

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    So what is the difference between the potentiometer output and your cruise-control output?
     
  17. kerrmotorsports

    kerrmotorsports New Member

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    The only thing I can think of is the potentiometer is never open, where as the the switches are naturally open
     
  18. crutschow

    crutschow Well-Known Member Most Helpful Member

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    Measure the voltage to the circuit from the switches and compare it to the voltage from the pot.
     
  19. 04colyZQ8

    04colyZQ8 New Member

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    Any luck getting this working? Trying a similar thing using a Colorado cruise switch ladder design.

    to output three wires to typical GM V8 cruise on, off, coast, set, r/a

    ON 850 ohms
    off 0 ohms
    SET 1200 ohms
    Resume accel 2900 ohms
     
    Last edited: Jul 6, 2014

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