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Thread: EBY701 questions and opinions!!!!!!!!!

  1. #31
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    I didn't look up the datasheet on a 555..but if you can't get a 5v pulse from it, couldn't you simply utilize a voltage regulator to step down that 12v to 5v when it's pulsed? Something like a simple circuit using an LM317T? Or perhaps using resistors...but I think the Vreg would be more reliable/safe.

  2. #32
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    yes the 555 will work from 3v to 18 v I think. And yes you are correct about the voltage. Most logic circuits run on 5 volts. But it would be a safe thing to do, to turn your monitor on, and put a volt meter across the contacts of your button to see what voltage the switch runs at. Also you would just use a power off circuit to trigger pin 2, the 555 would send another pulse to switch the screen input when you leave reverse.

  3. #33
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    yes you could also use the 7805 regulator to create a 5v source and or output. They are very reliable, they make several versions including a high current version that can handle like 2 amps. Just make sure you use a heat sink. BUt you shouldn't need that, as the relay can use 12volt source, and the circuit and trigger would use the 5v regulated source in the milli amp range.

  4. #34
    Maximum Bitrate pRoFiT's Avatar
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    LM7805 is great for 5v regulation. I'm tsure the screen is most likley running a 5 volt on/off switch. Probably a pull up resistor to 5 and the switch probably pulls to ground. So depending on the pull up resistor in the monitor you could probably get away with the 555 directly to the pull up side of the switch.

    Another thing you may be able to do is use an and gate to determine if the monitor has turned on by wiring directly to the power led? it is most likly less then 5Volts, which is needed for a and gate to trigger, but i think the datasheet on the generic 7408 AND gates can trigger from 2.5V......however leds run around 1.8 volts so you may not be able to trigger from an led.....i'm rambling...long day....

    You could put together a simple (complicated?) PIC16F84 chip and write the code to handle such things as monitor is on and car starts in park so first switch on will be reverse etc etc. Sounds like a good project for me to work on Maybe i will layout a schematic and write some code. I have two video inputs i dont use on my touch screen and access to tons of 12VDC cameras


    Edit: Another thing i just thought of. If you use some 555 timer or pulse relay for every on/off from the reverse light what happens when you go from park to drive? will it be fast enough as you change from park to drive while changing through reverse? Just a thought. My car is old and reverse i have to push to the right on the column to make my reverse lights come on. So it would be even more tricky for me to try this setup.
    Um, I guess this is where you put something witty.WITTY

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  5. #35
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    I think it would be safer to use relay on pulse to "press button"

  6. #36
    Who am I? HiJackZX1's Avatar
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    Quote Originally Posted by katit View Post
    I think it would be safer to use relay on pulse to "press button"
    I was thinking the same thing.
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  7. #37
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    Actually profit, a PIC circuit with the proper code would be the real deal for this poject As you could incorporate all of the info, and logic into one circuit instead of making a million timers to do the same thing, the pic could do it all, ie: look for monitor state, is power on? if yes, is car in reverse, if yes, fire trigger, if no wait() rinse, repeat... and so on, it would constantly monitor the state of the monitor and gear and automaticly change as needed. Unfortunately I am not much of a programmer, and my Pic projects have always been restricted to the code, made free and readily available by other people. If you can wite the code for a PIC I say do it, and either sell the unit pre programmed or have the info available here, as many people would beable to use that circuit for numerous things.

  8. #38
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    Anything we do with PIC will not make it 100% You still don't know which state monitor in currently. Put car in reverse, on-off monitor and here we go - they out of sync.

    I think I found solution.
    http://www.pac-audio.com/instructions/TR7bonus2.pdf

    PAC TR7 newest version bonus feature #19


    Here is my plan:

    1. Assume that monitor on with a car and in VGA mode
    2. When I put in reverse (power in reverse lights) - I switch mode and turn camera on
    3. When I push button - (power to camera from latched relay) - do the same.
    #2 and #3 will be diode isolated.

    PAC TR7 will see power on/power off and send pulses to mini-relay that will trip monitor button. Seems to be $40 or so worth of parts. Would be cheaper to get proper monitor at beginning

  9. #39
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    I havnt read about PAC TR7, but your wrong about PIC. The PIC can recognise if the monitor is on or off, and it can recognise what state the monitor is in, via inputs as well as what gear is tha car is in via the cars own neutral safety switch as an input. It is simple logic and alot of PIC circuits already do this. I just don't have any programming skills to do it and make it car specific. But maybe Profit does.

  10. #40
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    I think it's do-able with a PIC, but you're going to go thru a lot of work tracking down signal lines and then your device will only work with the EBY701. I also think it will require tapping into the LCD's circuitry a lot deeper than most people would feel comfortable with. You might have to wire the PIC into an LCD circuit trace that could be difficult for a person with above average soldering skills, much less someone who's never soldered before. I wouldn't have any problems with it as I used to do some of this work for a living, but I don't want to hear the crying when someone bricks their monitor from a bad soldering job.
    -Jim
    Nipomo, CA

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