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  •  » Hey BB I was just going to send a PM but wouldn't let me include a PIC

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    12/10/2013 6:21 AM  #1

    wsinsle
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    From: Belle Vernon, PA
    Registered: 4/01/2013
    Posts: 1,662

    Hey BB I was just going to send a PM but wouldn't let me include a PIC

    BB added atime delay to the low fuel and got this to work well on the bench. The Low Fuel has about a 50 sec time delay then seals in. Time delay will vary slightly with resister tolerance. LED 3 comes on with low fuel and is for set up purpose only. LED 4 comes on after time delay and seals in. To help cut down on parts, I used the last comparator on the 339 chip for the time delay. It's a basic R/C timer. One issue I had was at times the seal in was coming on during power up. (Basically when you would turn the key on) The 4.7K resister between the capacitor and ground seems to have solved that. Basically the way these work are when the negative input raises above the positive input the output turns on. When the output is on it completes the path to ground (-). (Open collector) My thought is to have some professionally make circuit boards, if I do I'll be happy to give you one.



     

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    12/10/2013 5:51 PM  #2

    Bullet Bob
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    From: Montrose, Colorado
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    Re: Hey BB I was just going to send a PM but wouldn't let me include a PIC

    Walt,

    That is really cool.  Sorry but I haven't been involved in this progect lately...too busy with all the other things I need to do to get the car ready to go back together.

    That looks like a good solution and pretty simple to build...think I will add one into my new harness.  Maybe put a small LED at the bottom of the gas gauge.

    Thanks again for all your work.

    BB

    "you get what you pay for, good work isn't cheap, and there are NO free lunches...PERIOD!"
     

    12/11/2013 6:58 AM  #3

    wsinsle
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    From: Belle Vernon, PA
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    Re: Hey BB I was just going to send a PM but wouldn't let me include a PIC

    BB

        My thoughts on set up. Set the fuel gauge up according to your kit. After the gauge and 5 volt adjustable supply is set, remove the wire from the fuel gauge going to the sending unit. In its place connect a 100 ohm Pot from the gauge to ground. Adjust the 100 ohm Pot until the fuel gauge reads where you want the low fuel light to come on. Now adjust R5 on the circuit board until LED3 just comes on. Remove 100 Pot and reconnect the sending unit to the gauge.
     

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    12/18/2013 3:59 PM  #4

    John Ha
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    From: Mitchell, SD
    Registered: 4/02/2013
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    Re: Hey BB I was just going to send a PM but wouldn't let me include a PIC

    This is NEAT!!!   Will this work with the factory CVU instead of the 5V regulator supply (maybe with the addition of a 5 - 10 μf cap)?

    Last edited by John Ha (12/18/2013 4:03 PM)

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    12/18/2013 5:52 PM  #5

    wsinsle
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    From: Belle Vernon, PA
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    Re: Hey BB I was just going to send a PM but wouldn't let me include a PIC

    John I would think not, but I've been wrong before. I think you would need a fairly large cap to level out the voltage for the LM339 chip to work properly. You could use non-adjustable 5 volt P.S. Another thought is if someone only wants the low fuel I think a LM393 chip is half of the LM339.

    Last edited by wsinsle (12/19/2013 10:36 AM)

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