Convertible Top help

Discussion in 'The Projects Forum' started by jdub765, Mar 5, 2009.

  1. jdub765

    Thread Starter Member

    Mar 5, 2009
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    I'm trying to create a one-touch solution for the convertible top on my car. I've been having a bit of fun brainstorming w/ relays and modules and whatnot, but I can't seem to find an ideal solution.

    The problem: I'd like to be able to hit the open once, and then hit it again if I want to interrupt the open sequence. I essentially need a timed latched relay that will stay latched for 25 seconds, but can be interrupted by pushing the same button at any time.
    Repeat setup for the close button.

    I was looking at ways to use a DEI 611T or 528T, also considered some other modules, but I couldn't figure out a good solution on my own.

    Do you guys have any recommendations?
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Having owned a number of convertibles over the years, I'd be quite hesitant to attempt such a thing. The last few inches when nearly up, and likewise when nearly down, can be mighty critical. Also, I'll suggest that the up or down event shouldn't be timed; there should be limit switches that cause the latch to disengage when the top is nearing it's destination. More importantly, the load on the motor needs to be monitored; if the top should begin to bind (or strikes an object), the latch should be released immediately. The latter can be problematic to set up, as the load will be quite high when it's first started along it's way.

    As you can well imagine, there are safety implications when undertaking a project like this. Failure to plan it right and build it properly could possibly result in serious injuries or expensive property damage.
     
  3. jdub765

    Thread Starter Member

    Mar 5, 2009
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    Yeah, I'm aware of the dangers and risks, so I'm going to be careful when opening/closing the top, as well as the reason why I'd like a second button push to interrupt the sequence.

    The timed feature should be okay, as it is okay to hold the physical button down for as long as you want. The top knows when it's reached its fully open/closed state.
     
  4. jdub765

    Thread Starter Member

    Mar 5, 2009
    15
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    I diagrammed my idea for using the 611T below...
    The problem with this setup is that on the second push (to cancel the squence), once the left relay cuts power to the 611T, and the change propagates through the 611T, then the right relay, then the left relay, it's back in the start state, and if the button is still being held down, it could start the sequence again.
    Another problem is if the 611T will remember its last state when power was cut to the module...
    [​IMG]
     
  5. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    You can use a decade counter and use each of its outputs for a certain function. At each button press the counter will increase by one and it will change to the next output. Note that you will need a debounce circuit for the switch.
     
  6. jdub765

    Thread Starter Member

    Mar 5, 2009
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    Hey that's pretty cool. I have a few questions, please bear with me as I have a comp sci background, not EE, so I only know what I've just Googled...

    So I'm assuming that the button would be Clock pin 14's input, after going through a debounce circuit. The output pulse seems to hold until the Clock's pin goes high again, which shouldn't be too much of a problem. The 611T can be triggered on the leading edge of an input, but it has to be negative, but I can figure out a way to convert that.

    I had a question about the reset function on this chip. How does it work? It looks like it has to be set to 0v (ground?) to be enabled. So if you remove it from 0v, it defaults back to output 0?

    This chip always seems to have some sort of output as long as it is given power, so I gotta figure out a solution where it only outputs when the button is pressed...
     
  7. mik3

    Senior Member

    Feb 4, 2008
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    The chip will output a high on the first output (Q0) when turned on.

    If you drive reset low the chip will output a high on Q0. Also, you can connect the reset to any output as if you reach this output the chip will reset automatically.

    Which chip are you talking about?
     
  8. jdub765

    Thread Starter Member

    Mar 5, 2009
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    Oh, I guess I was referring to the 4017 chip. I just googled "Decade counter" and found this: http://www.doctronics.co.uk/4017.htm#pb_04

    I'm not sure that this chip would work. I'm trying to figure out how to get the chip to reset, give the diagram above.

    Maybe I'm approaching this wrong, and ought to just build something from scratch, instead of using the 611T and some relays.
    Would it be hard to build something from scratch for someone who's never worked with ICs before?

    I'm thinking that if I use some clock chip (555?) and two nested (correct term?) decade counters to count off 30 seconds, it'd be a good start... You guys probably have better ideas...
     
  9. jdub765

    Thread Starter Member

    Mar 5, 2009
    15
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    Here's what I had in mind... Please excuse my goofy drawing skills, and the oversimplified diagram.

    I based this on the understanding that there exists a latched relay that will switch between two outputs when the trigger input goes high. I'm also assuming that the decade counters reset when power is removed.

    I don't think the relay is required. I don't know if the diode is required.

    The switch for the top is in the lower left.

    [​IMG]

    What do you guys think?

    Any recommendations on what chip to use for the clock? I understand that the rate that the 555 chip counts depends on the voltage of the current supplied, which won't work in a car :(
     
  10. jdub765

    Thread Starter Member

    Mar 5, 2009
    15
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    Sorry, I guess my questions were too simple...

    Well, I've built the timing circuit w/ a 3 hz 555 clock and two decade counters.

    I've run into a problem with the latched relay. I bought some latched relays, but they all require the polarity to be reversed to flip the latch. I need a relay that can switch when receiving a pulse on a single input.
    I found this but I don't know what the technical name for it is, so I can discern between this latched relay and others.

    Can you guys help me out so I can find the relay on digikey?
     
  11. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    You need to have some sort of "Abort" switch that will reverse the top, as well as a lockout while not in park, maybe piggyback the Neutral Safety Switch.

    Example: Driving 65mph, button gets hit (everything gets bumped in a car at one point or another). Top starts either going up or coming down - top is ripped from car, possible accident.

    Abort: Some top motors have tremendous torque, it starts closing/opening and a girl in the back seat has her hand caught in the brace. With the current setup, there's nothing you could do but watch.
     
  12. jdub765

    Thread Starter Member

    Mar 5, 2009
    15
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    The way I drew my goofy circuit allows for an "abort" function if the button is pressed a second time.
    The lockout function is built into the car's own control modules, which won't let the top operate if moving >2.5 mph.

    I just can't find the right latched relay =(
    [​IMG]
     
  13. jdub765

    Thread Starter Member

    Mar 5, 2009
    15
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    I'm having problems with my timing circuit :(

    For some reason, the second decade counter seems to be starting more often than not at 6 rather than 0.

    Does anyone know why this might be happening? Is it because of the charge the capacitors hold?
     
  14. jdub765

    Thread Starter Member

    Mar 5, 2009
    15
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    Any suggestions to why the second decade counter is starting at 6? I'm sort of stuck, as this is beyond my basic understand of circuits...

    For the latched relay, I'm using a chip with dual JK flip-flops and then I'm going to use its signal to trigger regular SPDT relays.
     
  15. jdub765

    Thread Starter Member

    Mar 5, 2009
    15
    0
    I'm still stuck on this issue... The second decade counter seems to like to start at 6 rather than 0 :(

    Is there information that I am missing for someone to help me on this?
     
  16. jdub765

    Thread Starter Member

    Mar 5, 2009
    15
    0
    I'm starting to work on this project again after taking a break for a few months. I've looked around on the web, but I can't seem to find info that pertains to my problem. An EE textbook might help :D

    Can someone help me out?
     
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