Autometer sensors

ar4me
Posts: 16
Joined: Mon Apr 28, 2008 4:19 pm

Autometer sensors

Postby ar4me » Thu May 15, 2008 3:14 am

Hi all,

I'm about to install a Dash2 in my race car. Since I already have autometer gauges+senders for engine oil temp and transmission+diff oil temp, I would like to re-use the Autometer senders. Has anyone done this? Know the equations to use (250F autometer senders and gauges)?

Also, I have a FuelSafe fuel cell and fuel level sender + gauge (think the source is Autometer). Does anyone know the equation for the fuel sender? And, how to connect it? The fuel level sender currently takes +12V, ground, and puts out signal. Do I just use the 5V from the Dash2 instead of +12V, or do I leave the 12V as is? Though, I'm afraid the signal will then have a range of 0-12V (which I assume is too much for Dash2 - 5V max I think).

Thanks for any help,
Jes

DavidRowley
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Postby DavidRowley » Thu May 15, 2008 11:24 pm

just my opinion but


if al the sensors are Voltage output sensors you need a 0-Degrees setup . or referance temperature

you take the sender put it at a know fixed temperature 0 degrees is simpe cold water filled with ice leave for 5 mis the water is pretty well 0 degress as the ice melts the voltage read on a multi meter recorded take the water to 10 20 30 40 50 degress on a stove with a electroninc Sensor placed in the water next to your sender this requires a calibrated sensor but most hospital temperature mercury guage sensors can be trusted for calibration

take the voltage reading as the temperature rises and log them all as high as you can go this crates a map of the sensor for your range

simple using the RT software you can enter these values and Hey presto your sensor is calibrated the DL1 has both 5V and 12V inputs i belive so simply use the 12v Input and set the data for that analogue channel


as for the fuel level sender it sends 0-12v for the lvl empty the tank add say i gallon take a reading keep adding one gallon at a time taking readings till the tank is full and again transfer the data to the RT software

it is simple but sounds hard i know

Tools required for all sensor setting up is a multi meter and a little lateral thinking

ar4me
Posts: 16
Joined: Mon Apr 28, 2008 4:19 pm

Postby ar4me » Thu May 15, 2008 11:38 pm

Hi,

Yes, I'm aware of calibration methods, but I would prefer not to have to pull sensors (not easily accessible) if someone has already done the measurements or know of spec sheets (as it appears someone has found for VDO). They are not voltage sensors, but impedance, though that is easy to deal with using the 1 kohm like RT does for some of their own sensors. The fuel level sender is voltage based, so there I just need to pull the sensor and have it in a cup and record voltage as fuel level is increased.

Still curious if someone has specs for the 250F Autometer oil temp senders.

Jes

Gregg
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Location: Arlington, VA
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Postby Gregg » Wed May 21, 2008 2:32 am

The equation I have for the Autometer 2258 temp sender for water temp in degrees Fahrenheit is:

y = -6.6151338523616x^3 + 55.4540684157546x^2 - 186.83368x + 377.86

ar4me
Posts: 16
Joined: Mon Apr 28, 2008 4:19 pm

Postby ar4me » Wed May 21, 2008 2:40 am

Thanks 8)

Just last night I measured the 2258 (impedance as fcuntion of temp from 40F to 210F). I'll plot and compare to your mapping - will post the plots.

Thanks again,
Jes

ar4me
Posts: 16
Joined: Mon Apr 28, 2008 4:19 pm

Postby ar4me » Wed May 21, 2008 3:05 am

Greg,

What supply voltage are you using? 5V? and, what pull-up resistor are you using? 300 Ohm. With 5V and 300 Ohm my measured data matches your equation quite well.

I was about to post a screen-print of the Excel sheet comparing plots of measured data vs. the quation above (assuming 5V and 300 Ohm), but then realized that this board does not allow uploading of pictures :(

Jes

Gregg
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Postby Gregg » Tue May 27, 2008 8:13 pm

Yup...5v and 300ohm

ar4me
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Joined: Mon Apr 28, 2008 4:19 pm

Postby ar4me » Wed May 28, 2008 4:32 am

Cool 8) Thanks for confirming.


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