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Thread: I'm at it again! Digital Dash Number 4!

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    Default I'm at it again! Digital Dash Number 4!

    I got inspired and decided to build a new digital dash for my car! A little background. I built the first one in 2003, and it was really just a static overlay that used LED digital numbers for things like the speed and tach displays, and there were cut-outs in the overlay where I could see the factory analog needles point to these LED digital numbers. So, the speedometer had numbers made out of LED's that said "40 50 70 90" next to a cut-out, and through the cut-out, I could see the factory needle point to the speed. It wasn't really digital, but it had a digital look. However, this panel did have actual indicators, such as turn signals and hi-beams, that were hooked up to the car's wiring for those indicators. I built the second one around 2010, and it was similar in concept, but was more readable and had a more modern look.

    In 2015, I built the third version, which was a real digital dash, with actual digital readouts for speed and tach using programmable tach/frequency displays that I got off of eBay. I also made bar graphs for volts and temperature, though the temperature gauge just got its data from a thermistor mounted on a radiator hose, making it approximate. This panel still had cut-outs for the factory fuel and temperature gauges, as well as the odometers. This one was very much inspired by the Knight Rider KITT car's dash, and has worked well for nearly three years, except for some accuracy issues with the tach.

    New for 2018, I have taken the Knight Rider dash theme to a new level with cool looking blue and purple graphics, combined with the red LED digital displays for speed and tach. Instead of bar graphs, I am using blue mini-digital voltmeters to show volts and temperature, using the same thermistor-system I used above for an approximate temperature reading. I am still utilizing cut-outs for the factory fuel and temperature gauges, as well as the odometers.


    This picture shows the basic panel outside of the car. Keep in mind that a smoked-plastic panel goes in front of it, so you don't see many of the imperfections on the dash panel when it is installed.

    DD4-4.JPG

    This picture shows the wiring on the back side of the panel. The green circuit boards that you can see are for the speedometer, tachometer, and other displays. I did not actually build those circuits. The larger ones are tach/frequency displays for tach and speed, and the smaller ones are voltmeters that I'm using for the other functions such as volts and temperature.

    DD4-3.JPG

    This picture shows the panel powered up on a little test board that I initially built about four years ago. This little test board has proved very useful for designing and testing circuits, allowing me to temporarily wire up circuits and wire in pre-mounted potentiometers and capacitors without having to keep twisting and untwisting wires.

    DD4-6.JPG

    This picture shows a night view of the panel and surrounding control panels.

    DD4-9.JPG

    This is a close-up of the dash in the car.

    DD4-10.JPG

    I also have a picture that is more like a day view of the dash. It was taken at night, but used the flash. However, for some reason, the site would not allow me to upload it. Maybe I reached an allowable limit for uploads? So, you can see that picture at this link:

    https://app.box.com/s/w44xrox39ce1n54dxzg61l4sabffs1fj


    In reality, the project is not quite complete. I still have to finish the wiring of the temperature gauge, which is why it says "000". And, under the tach, there is another digital gauge, also currently saying "000". I'm not yet sure what I will do with it. I may make an estimated wheel horsepower module for it. But, you can clearly see how it looks. I'm quite pleased with how it's coming out.
    Attached Images Attached Images
    Last edited by Excelsior; 05-12-2018 at 02:56 AM.
    And when I came to, I had a VISION! A REVELATION! A PICTURE IN MY HEAD! A picture of THIS! The FLUX CAPACITOR!

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    Hope you enjoyed the "dragon" - zx2loon Me wubbz joo too!! - zx2loon Congrats bro!! - rascal get 'em done - GoT MiLF? Unicorn hood ornament! lol - rascal 
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    KITT would be proud! Pretty badass. I would buy one if I still had a ZX2.
    2000 Black S/R (RIP), Iceman/CF hood/PnP ATX TB/K&N/MSD/PowderUDP-ODP/Esslinger cam gears/50shot/PS STS/SPI MTX/Fidanza/Stage2/Kamikaze/2.25"cat-less/Magnaflow/SCT(Pwned by Vit)/STB/21mmRSB/KYB/GC/Drag DR23
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    Thanks! Unfortunately, these things take me so long to build that I'd have to charge about a million dollars for one if I tried to sell them! I've been working on this one about 2 months now.

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    Nice job man! IIRC, in your last update you were having problems with the tach signal? Did you manage to get that resolved for this new version?
    "The bitternes of poor quality remains long after the sweetnes of low price" -Ben Franklin

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    I'll have to drive it around a while to see if just the fact that I'm using a new display module helps. Previously, I tried using a wire from the coil pack (and I had to put high resistance in it as it was fairly high voltage), but I could never get a consistent reading from it. It would more or less change with RPM, but would often make sudden large jumps in the reading. Before taking out the old panel, I even tried to mount a coiled wire by a spark plug wire to inductively pick up that pulse, and it behaved similarly to the coil pack wire. I'm wondering if the BCM sometimes tells the coil pack to fire two cylinders at once under certain conditions.

    So, I'm using a DEI tach signal generator mounted near the alternator.

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    Fairly certain these are wasted spark coils, so it would fire 1&4 together and 2&3 together

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    ^^^
    I did a Google search that actually took me to an old thread on this site, and that appears to be the case. I also read (not sure if this is true or not) that when the two plugs are firing simultaneously, that one will have a positive polarity, and the other one a negative one. Maybe that is what is confusing my gauge. Perhaps mounting an inductive loop near a sparkplug wire, then putting a resistor in line to drop the voltage and a diode to allow only one type of pulse to go through, may help. I may try that someday, but not right now. The DEI tach signal generator is working okay, but still sometimes reads 200-300 RPM low, so the problem was not in the old dashboard's gauge, as I bought new gauges for the new dash.

    Other things I've found...

    I got the temperature gauge hooked up, and it works quite well, considering how I'm sensing the temperature. Basically, I just have a thermistor (temperature-controlled variable resistor) mounted on the upper radiator hose. It is sensitive to air blowing under the hood when the car is in motion (the displayed temperature drops while the car is in motion), so it is more of a guideline (and, let's face it, also more of a light show) -- but I do still have the factory gauge visible to make sure no overheating is taking place.

    I used an interesting method to make that temperature gauge. I am using a 3-wire voltmeter -- and by 3-wire, I mean there are 2 wires that actually power the meter, and the third wire that is the actual voltage sensor. This is important, because it allows the meter to measure voltage down to 0.01 volt -- a basic 2-wire meter gets the power to operate it from the source of the voltage you're measuring, so that if the voltage drops below 2-3 volts or so, it won't work because there is not enough voltage to power the meter and its LED display.

    With this meter, I knew I wanted it to be able to read anywhere between about 80 and 250 for the temperature, so since it can measure down to 0.01 volt increments, I figured it could read 0.80 to 2.50 volts, and I put a tiny piece of electrical tape over the decimal point. Then, I have two potentiometers hooked to that voltage signal line -- one of them in series, to simply lower the voltage reading, and the other one hooked to ground, which causes the circuit to draw more current as the resistance of that pot is lowered. This effectively controls the sensitivity or range of the meter reading. Because of this, I would not hook such a circuit to the factory temperature sensor, because it could pull more current then the circuit was designed to handle and burn something out. I experimented and zeroed in on settings that seem to approximate the temperature pretty well.

    Another thing I've discovered is that these blue LED's that I got off of eBay are very touchy, and I will likely not use them for any other projects. I have already replaced about five of them. I don't know if it is due to manufacturing defects, or whether I damaged them during soldering the connections. They worked fine at first, but after a few days, they started cutting out. At first, increasing the brightness kicked them back on (I have a potentiometer that controls the brightness of the LED graphics). But I had to raise the brightness more and more to get them back on, and then finally, they would not kick back on even at maximum brightness.

    In general, I am running groups of 3 LED's, with the 3 LED's hooked in series, and I have an approximately 2000 ohm resister in line, so I am not running them anywhere near their rated voltage or current. So, I'll see if I got all the bad ones out. But I am considering other options. One possibility is just using white LED's and putting blue tint over them, as I have not had these issues with the white LED's that I'm using.

    And speaking of tint over white LED's, that's exactly what those purple-looking LED's are. I bought purple LED's and I started mounting them to the dash as I was building it. But then, I noticed that, while the LED itself lit up purple, if I put a plain white piece of printer paper over it, the light showing through the paper was sky blue! From what I can tell, there was more than just purple light coming from those LED's -- I'm thinking there is also ultraviolet (UV) light coming from them, as well. Granted, it is probably a low level of UV, but I did not want to take any chances having my dash shine UV right into my eyes whenever I'm behind the wheel, so I took out the purple LED's and replaced them with white ones, and then I put tint over the white LED's to make them look purple.
    Last edited by Excelsior; 05-20-2018 at 10:41 PM.

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