Author Topic: Adding Gauges to an FC - Clean 12V power etc  (Read 1116 times)

0 Members and 1 Guest are viewing this topic.

Offline toplessFC3Sman

  • Sr. Member
  • ****
  • Posts: 405
  • Karma: 8
Adding Gauges to an FC - Clean 12V power etc
« on: August 20, 2012, 08:43:42 PM »
Well, about a month ago, my ProSport boost gauge decided to start going nuts occasionally, randomly moving around on it's own, and now it just flat-out doesn't work.  After talking to a PS rep, he indicated that it was probably due to a voltage spike, possibly from jump-starting or alternator voltage spikes. Unfortunately, this is the 4th gauge from them that's burned out, all at approx 2 year intervals.  Anyhow, it gave me a reason to re-do the power supply to the gauges, and clean up the installation a little bit.  I've been drawing power for the Innovate AFR, and ProSport Boost & EGT gauges from the warning light cluster on the dash, and running the signal wires up behind the dash and out through the same opening as the warning light cluster.  Until now, the various wires have been routed around the cluster, and that's put considerable stress on the cluster & dash plastics, and i'm sure it contributed to the poor state of the warning cluster trim plastic.  Anyhow, here's what I'm doing to try to clean up the voltage signal, as well as the aesthetics of the gauge installation.

First, the cluster modifications... I had to pull power, switched power, a headlight signal, and ground to get the gauges to work & change color when the headlights were on.  So, since the clock never worked anyway, lets cut it off to make some room, and tap into those wires.

Cluster disassembled


Here's a bunch of diodes, resistors etc that provide power to the clock & handle the knob to set the time on the top board.  On the bottom board, you can see where soldered some wires to tap into the power & ground.  Red is constant 12V from the batt, Blue is switched 12V with the ign, Green is +12V when the headlights are on, and Black is ground.


Lets cut off the whole clock area (to the right of the cut), making sure not to cut any of the warning light traces (to the left).  You can also see that I trimmed the bottom board around the connector and traces, and unfortunately slipped & broke 3 of the traces


No worries, just take a little wire, solder it to the back of each of the connector pins, and then to some place further down the broken trace, effectively bridging the hole in the circuit that my slip with the saw caused. (shown by the new pink wires)


Another shot of the portions of the boards I cut away to make room for wires


Now for the back casing

And the front casing, warning light panel, and the tinted cover.  I tried to just snip the white plastic casing, but it was too brittle and snapped elsewhere too, necessitating some glue.  The clear cover I patiently sanded down with a half-round file to make sure I wouldn't crack it, and the warning light panel was done with some scissors.


Same shot, but you can more clearly see the wire anchor screwed into the front casing, and how knots were tied in the wires so that if they get tugged on, the stress gets applied to the wire anchor, not the solder joints.


And the gauge cluster itself, plus some Bells 2-hearted.  Tasty stuff.  Anyway, the cover for the gauges is some thin aluminum I picked up at the hardware store, cut out with some metal shears, bent into shape and painted dull black to cut down on glare, and the gauges are all mounted behind on a thicker strip of aluminum.


The strip of aluminum, and the suction-cup mounts to stick the pod to the windshield.  These were just generic cheap ebay GPS mounts for about $2 each that I cut up and bolted onto the pod, so that the bottom of it rests on the dash over the warning lights, but the suction cups really hold it in place.  They've worked great for a number of years now.  There's also the back of a normally-closed momentary switch for power to the Innovate AFR gauge, since I need to cycle power to it once in a while if it doesn't start up properly.

I've got some components on order from Digikey to make the circuit to clean up the 12V power & remove any voltage spikes, and those will hopefully get here by the end of the week.  The components are:
MOV - 12V surge absorber P7315-ND
Zener Diode - 12V, 1 watt, voltage limiting diode 1N4742ADICT-ND
Diode - 1N4001
Capacitor - 0.001 microfarads

I plan on building two separate filtering circuits, one for the 12V battery power and one for the 12V switched power, since both of those do get connected to the logic side of the gauges, so two of each of the above components will be required


Offline fidelity101

  • Sr. Member
  • ****
  • Posts: 462
  • Karma: 4
Re: Adding Gauges to an FC - Clean 12V power etc
« Reply #1 on: August 21, 2012, 09:30:29 AM »
classy! I wanna see it in the vehicle.

Offline ~Groll69~

  • Administrator
  • Rotary God!!
  • *****
  • Posts: 1235
  • Karma: 1
  • Gender: Male
    • Elegant Lady Bridal and Tuxedo
Re: Adding Gauges to an FC - Clean 12V power etc
« Reply #2 on: August 21, 2012, 01:48:55 PM »
Keep up the good work.
"Long Live Rotary"

An RX-7 is like having a slut as a gf! She will love you, but she will also screw around with the guy at the parts store, most of the local cops, your insurance agent, your apex seals, your bank account and your credit card!!!

Offline toplessFC3Sman

  • Sr. Member
  • ****
  • Posts: 405
  • Karma: 8
Re: Adding Gauges to an FC - Clean 12V power etc
« Reply #3 on: September 04, 2012, 08:13:19 PM »
Well, I've had the gauges in the suction-cup holder for a while, and have been pulling power from the warning cluster for almost as long, but finally decided to clean it up and install the conditioning circuitry.  With that said, here's the info on making the actual circuitry.

The design for the 12V conditioning circuit came straight from the MegaSquirt V3.0 board design, which You are not allowed to view links. Register or Login; I've used bits of the design in numerous projects so far.  The part we're going to be using is:

For reference, the components as listed in the diagram are:

MOV1: MOV - 12V surge absorber P7315-ND
D13: Zener Diode - 12V, 1 watt, voltage limiting diode 1N4742ADICT-ND
D11: Diode - 1N4001
C15: Capacitor - 0.001 microfarads

Since some of the gauges draw power from constant +12V from the battery, and others from switched +12V, I built two of these circuits, with just the ground shared between them.  Since I had a couple of blank PCB's from radioshack (without integral traces), I laid out the components in one of them, using the extra length of the component leads to basically make the traces.  For example, the MOV's inserted into the board, with the leads bent around, seen from the top:

and the bottom:


And now for the circuit itself, just about finished, with the circuit diagram overlayed - black is ground, red is 12V



Soldered up with the wires connecting it to the warning clusters, and out to a connector that's attached to the gauge harness


And tucking the circuit board into the void left by removing the remains of the clock



The plug to the gauge harness peaking out of the warning light surround


And reinstalled


Warning Lights still working


And lit up with the headlights

Offline fidelity101

  • Sr. Member
  • ****
  • Posts: 462
  • Karma: 4
Re: Adding Gauges to an FC - Clean 12V power etc
« Reply #4 on: September 05, 2012, 10:37:40 AM »
Are you an electrical engineer? because you should be.

Offline toplessFC3Sman

  • Sr. Member
  • ****
  • Posts: 405
  • Karma: 8
Re: Adding Gauges to an FC - Clean 12V power etc
« Reply #5 on: September 09, 2012, 06:25:18 PM »
I'm a mechanical engineer, but between the megasquirt, formula SAE and a number of other projects I've become pretty familiar with circuitry.  I couldn't explain 50% of why the circuit there works to clean up the power supply, I'm just copying and re-creating a known solution for cleaning up a power signal.