Hello! I am a complete novice here and am beginning a project to try and convert an old motorcycle dashboard for use as a sim racing dash. I have some experience building electronics based off of schematics, but this is my first foray into trying to do something without specific pre-written instructions.
This will be a long one, so please bear with me.
I'm going to walk through what I've put together so far along side the reference materials I'm using to aid in my design process.
To start, I came across this youtube video, which is now outdated, about using a vehicle cluster from an e36 BMW. https://www.youtube.com/watch?v=L59NL9EuEdM
While this is super cool, I really wanted something that has the ability to display higher revs and has a smaller footprint in my simrig. After a bit of browsing ebay I found a cluster from a Kawasaki Ninja ZX-12R.
Going through the service manual this cluster seems to hit the sweet spot of being a predominantly digital cluster driven by analog inputs.
Here is the schematic I've put together. I tried to lay everything out to be as minimally confusing as possible. If you have any recommendations on refining the schematic I am open to suggestions. I'll reiterate that i have almost no idea what I'm doing so, if you see problems please point them out! I haven't purchased any of the components yet I wanted to get confirmation of my approach and solve a few problems before beginning to assemble hardware.
Starting on the left side, I'm currently planning on using a generic amazon 12v DC 5A power supply
I'll then be using this 12VDC to 5VDC 5A step down to power the Arduino and Relay Board:
Moving to the right we have the Arduino Uno. My choice of output pins is somewhat random but I've tried to keep pins that may need to output PWM in the right places. I've come across conflicting info on issues using pin 1 and would appreciate confirmation that I should or should not use pin 1 to trigger a relay.
Skipping the middle section for the moment, we have the dashboard at the top right. I was able to locate a service manual which lists the pinout for the dashboard as well as information on what signals the dashboard wants to see.
Going to the center left of the schematic, we have the tachometer. Based on the information in the manual the tachometer pulse is +12v-0v square signal with 100hz equaling about 3k on the gauge itself.
I am using a TIP120 Power Darlington transistor to step the 5v PWM signal up to 12v based on the instructions I found here: Arduino After Market Tach support · SHWotever/SimHub Wiki · GitHub
I don't think there will be a problem with this circuit based on the number of other clusters I've come across people using this same schematic for.
Next is the speedometer, which wants a 5v pulse. Awesome, I think I can just wire it directly.
Now we get to the part of the schematic where I legitimately have no clue what I'm doing at all. The fuel and temp gauges measure resistance in order to display their values. The testing documentation for the cluster it calls for using a rheostat set to specific resistances to check gauge function. I've looked into digital rheostats, but 12v options seem pretty limited and their function even more so. A digital potentiometer might work, but I don't know enough about how these components work together electrically to make that call. A third potential option is using a tone output. This is how the data is fed to the e36 cluster and if possible here would just mean adding a couple transistors. (e36 cluster documentation: BMW E36 Cluster Setup · SHWotever/SimHub Wiki · GitHub)
Here is the service manual documentation for the fuel and temp gauges.
Next we have the LEDs on the cluster and the ignition switch. Based on the pinout earlier in my post it looks like they all either receive 12v or are already supplied with 12v and need to be connected to ground. Originally I was going to try to design this with solid state relays, but after looking at costs for SSRs that would work, I've decided an off the shelf 8 relay expansion board designed to be used with an Arduino is the better solution. I'm planning on using this set of relays: https://www.amazon.com/JBtek-Channel-Module-Arduino-Raspberry/dp/B00KTELP3I
I can't remember where I came across it, but I found someone using a similar board and they were given the advice to have a 5uf capacitor across the power/ground connection for the relay board, so I've included that in the schematic.
As far as wiring the different cluster functions to the various relays, if a function has a hot (+) output that needs to connect to ground would it make more sense to wire that into COM and ground to NO? Or are they fine how they're currently shown?
Well, if you've made it this far, thank you. I look forward to your insights, ideas, and criticisms. Please let me know if anything needs further clarification as well.