# Hacking the Instrument Cluster



## e_canuck (May 8, 2008)

Hi Joe.

This is the only document I have on tach's . It was used by GM and dated 95. Your cluster could be a direct descendant. Hopefully.

http://www.national.com/ds/LM/LM1819.pdf

It does have sine and cosine notes on it. I can't read those diagrams but you can. I hope you find it usefull.

I do not plan on hacking the cluster. Good luck.

Take care,

DP


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## TX_Dj (Jul 25, 2008)

Wow that's some interesting info! Thanks for posting that, DP. I'm sure it will come in handy for many folks.


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## rfengineers (Jun 2, 2008)

Hey DP, Thanks for the information. "Air-Core Meter Driver" is what I needed to research the product.

The LM1819 is discontinued and I could not find any for sale, BUT this one is available, does everything the LM1819 does plus additional useful functions.

Digi-Key Part #
CS8190ENF16GOS-ND
$4.24 each qty-1

Joe


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## madmike (Jul 11, 2008)

What year Cars Make/Model use air core gauges?

Here what I found so far:
CS4122 (Triple Air−Core Gauge Driver with Serial Input Bus)
SA5778 (Serial triple gauge driver)
CS4192 (Single Air-Core Gauge Driver with Serial Input Bus) 
CS8190 (Precision Air−Core Tach/Speedo Driver with Return to Zero, FREQ_Input) (PDIP−16 package!!!)


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## rfengineers (Jun 2, 2008)

Now I am trying to track down a stepper motor driver for the odometer. The CS8441 that pairs with the CS8190 seems to be discontinued.


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## rfengineers (Jun 2, 2008)

I have successfully breadboarded an air-core meter driver using a CS8190. I can manipulate the readings of all the gauges by adjusting the frequency of a square wave signal from my function generator. Next step is to rig up a hall-effect switch and simulate my Tach signal.

I also breadboarded a stepper motor control using an MC3479. It is running off a pulse stream from the air-core driver. It's moving the odometer along quite nicely.


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## e_canuck (May 8, 2008)

DP


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## dtbaker (Jan 5, 2008)

I was thinking about whether it would be worth the time to feed some voltage to the fuel tank fuel level sensor to see if I could wire the battery pack voltage right there in my rear battery rack area where the fuel tank wires are to the original fuel gauge without having to even dig around under the dash.... but I already have a new calibrated gauge to install, and messing with that stuff is out of my league.

I WOULD be interested if people have ideas on that for future projects so I could maybe avoid buying the e-gauge, and maybe wiring the motor over-temp wires to the instrument panel warning light?


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## rfengineers (Jun 2, 2008)

dtbaker said:


> I was thinking about whether it would be worth the time to feed some voltage to the fuel tank fuel level sensor to see if I could wire the battery pack voltage right there in my rear battery rack area where the fuel tank wires are to the original fuel gauge without having to even dig around under the dash.... but I already have a new calibrated gauge to install, and messing with that stuff is out of my league.
> 
> I WOULD be interested if people have ideas on that for future projects so I could maybe avoid buying the e-gauge, and maybe wiring the motor over-temp wires to the instrument panel warning light?


I'm trying to decide if I should hook up controller or motor temperature to the old temp gauge.


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## dtbaker (Jan 5, 2008)

rfengineers said:


> I'm trying to decide if I should hook up controller or motor temperature to the old temp gauge.


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I think the over-temp wires on the motor are closed only if the motor overheats, so would be fine with idiot light connection rather than gauge.... 

fuel tank level voltage hooked to my traction batteries would be pretty useful if it gave a reasonably good idea of charge based on voltage. I dunno what that takes to siphon off a voltage reading and calibrate to what the fuel gauge was expecting. I would GUESS it was just some kind of 12v-based deal than could handle some stepped down voltage from the main pack.

d


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