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tapping into existing data sources

Posted: Tue Jan 13, 2015 4:56 pm
by jakekooser
Can this circuit be used in parallel with an existing gauge input, like a gas gauge or oil pressure gauge? My 1986 car has no OBD to tie into.
brentp wrote:Hi,

We're thinking that perhaps the 12v signal is causing a problem with the input circuitry and we would need to limit it to 0-5v. Would you be able to do a test with a resistor and a zener diode to limit the voltage going into the RPM input and tryting again?

The circuit would look like this:

Code: Select all

-----/\/\/\/\/\------X-------------RCP Input
    1K resistor      |
                     | 
                   -----
                    / \    5v zener diode
                   -----
                     |
                     |
                     |
                    GROUND


also described in this image: http://www.reuk.co.uk/Zener-Diode-Voltage-Regulator.htm

Let us know if you'd be comfortable trying this out.