RomRaider

Since this is a crossover type project, I think a few of you in here will be able to help me out. The short and sweet is I need a controller built/programmed (sorry its way beyond my learning curve) that takes my tach signal (I assume its a linear frequency change square wave) and uses it like a potentiometer to output a voltage. Basically, I want my tach to dim (or rather brighten) a series of LED's as RPM increases. I know it can be done. The whole middle part...escapes me. I've gathered I need to step 12v down to 5v to power the adruino, and step 5v up to 12 to power the LED's...I feel like PWM falls in here somewhere. Who is feeling creative? What the hell am I doing? Glad you asked. When Im on my "Track Map" in romraider, I want my demon eyes/halos/angel eyes to get brighter ("angrier") as RPM climb. There is a will here, someone show me the way.

Here's a related video

https://www.youtube.com/watch?v=Qgoe3KbEvTI

This sounds like a pretty easy project. Do you have all the hardware on-hand, and the skills to build it? Or are you looking for someone to build the entire thing?

You should only need to get a step-down converter to power the microcontroller (uC) from the car 12V. A good buck and/or linear regulator is likely sufficient, but if it were me, I'd probably use a flyback to isolate from the really noisy car ground circuit. Once you do that, it should be simple to just hook up your LEDs to a proper LED driver IC, or some discrete MOSFETs and use PWM from the arduino to drive the LED driver/transistors.

No, basically looking for a "here's some money build this for me" kind of thing here. I'd love to learn but this is beyond my learning curve and I'd like this sooner rather than later. I have the Arduino software downloaded and have been trying to watch videos and learn a little. I can do wiring ok, never tried circuitry though. Im hoping for basically a little black box with a few wires sticking out for power/ground/tach and LED output and some basic instructions on what and where to change in the coding incase I want to change the brightness at what rpm or whatever.

...I would attempt it, the coding is what scares me the most...but I would basically need my hand held so much on this its just easier to have someone that knows do it and be done I think. I feel like it will cost way more money taking the time to learn lol.

Do you know for sure what the signal on the tach wire looks like? Once that's figured out, the rest of the project is pretty straightforward.

FYI, I'm in northern MA near Lowell, probably about 1hr away from you.

square wave, frequency changes with RPM, something like 5 pulses per rev....I dont have an oscilloscope but I asked someone that does so I can get a range.

bump post. Happy Easter!

I'm definitely willing to help you out, but I am not interested in the 'pay for a complete system' model. This would be an iterative process where we have to have a bunch of discussions and some trial and error system design.

As a starting point, I could write some pulse width measuring code for the Arduino to see if the engine speed is easily readable. In this case, I would need you to be able to wire the system up and test the code. I could give pointers, but since i am not intimately familiar with your car or its wiring, my advice would be a guess at best.

If the car responds to SSM OBD commands, then this would be a much easier interface for gathering vehicle data.

Let me know if you'd like to proceed this way.

I do have another guy whipping up something he thinks will work but Im open to different ideas and help. So far this is a lets see what happens adventure. I should be able to help out with the testing and wiring and what not, the coding and I'd say soldering a circuit board are the parts I'm not up to speed with...along with when you get into voltage dividers, resisters, MOSFET's and the other stuff that might be needed when going back and forth with 5v and 12v and keeping electronics happy all around. Optocoupler seems like a good idea though. If I had an oscilloscope and could see what RPM was what frequency that would be a good start but no dice there and looking at cost, even less interest in getting one lol. Its not PWM though far as i can tell. It actually almost seems like my tach may be more of just a voltmeter in disguise but I didnt even really think about using the OBDII and whatnot.....obviously that is reading the tach signal. ive got different guesses, but nothing definitive beyond its a square wave and 1 pulse could be 1 rpm, 2 pulses could be 1 rpm, 4 could be...nobody really knows for sure yet. Im trying to not over complicate this. I still need to test the dimmabilty of my LED's, Im sure they are fine though. I tried to just run them off my illumination circuit and use the dimmer but that blew a fuse so apparently it was too much to add on there. I always have 4 projects going at the same time so this has been off the burner a bit while I dealt with other dumpster fires. But yeah your input is always welcome. Ill try and learn as much as I can. bottom line is this is definitely possible to do with the right minds.

If the ECU supports logging through the OBD port (which I'm sure it does), it would definitely be easier to just use a micro-controller to read the RPM that way, then use digital comms (I2C, SPI, whatever) to control a suitable LED driver. That's definitely the easiest and most robust way to set this up. Definitely easier than trying to read the RPM signal going in to the gauge cluster. Also will work for later-year cars, which from my understanding, don't use any analog signals to the gauge cluster and just use the CAN bus instead.

Sounds legit...cant picture the how-to in my head. So where do you intercept the tach signal to get it to a controller? I feel like no matter what, you are splicing into a wire somewhere, and outputting to the LED's +12v. They sell PWM dimmers for home LED lighting..I picture something similar just being controlled by the tach signal instead of a knob but the same kind of circuitry needed.

Here's an alternative way to get an RPM signal:

https://github.com/LegacyNsfw/AvcsContr ... ion-Sensor

I this is the sensor I used, not sure exactly but there are a lot of nearly-identical ones available on Amazon and ebay:

https://smile.amazon.com/gp/product/B00 ... UTF8&psc=1

Make sure you get one with a pot on it though, it's useful for adjusting the sensitivity, and not all of versions have it.