Technical > Wiring & Sensors
BMW tachometer
rob@vems.co.uk:
--- Quote from: antonch on January 08, 2008, 04:30:46 am ---Rob, your values worked out of the box, didn't have to modify/tune anything. Very odd how you knew them :)
--- End quote ---
They're the ones I use on the Nissan tachos, I didnt know anything about the BMW at all.
What size resistor did you use?
antonch:
--- Quote from: rob@vems.co.uk on January 08, 2008, 08:59:47 am ---
--- Quote from: antonch on January 08, 2008, 04:30:46 am ---Rob, your values worked out of the box, didn't have to modify/tune anything. Very odd how you knew them :)
--- End quote ---
They're the ones I use on the Nissan tachos, I didnt know anything about the BMW at all.
What size resistor did you use?
--- End quote ---
It's a cheapo RadioShack pot, supposed to be at 10K, but when I checked it was set to 9.2kOhm. Its funny, I turned on the car it took me a while to realize that the tacho worked right off the bat.
gunni:
I have always used a 1-2k ohm resistor and never had problems,
I think I´ll be installing the resistor on the inside between 12v and the appropriate channel pin.
jrussell:
If you use P259 Ch. 4 which seems to be pretty standard these days there are pads on the PCB for a pullup resistor.
Just please be careful. ;-) Its rather easy to damage things in there if you're not very skilled. The space is tight in that area.
In fact I really discourage the average owner to open their case, especially if it was a fully assembled unit you bought. Most areas of the World have support people that will gladly make modifications for you.
GintsK:
--- Quote from: rob@vems.co.uk on January 08, 2008, 08:57:14 am ---
--- Quote from: GintsK on January 05, 2008, 03:39:12 pm ---Did simple input signal for IGBT, MOSFET or output signal from stepper chip work without pullup?
--- End quote ---
No because the IGBT, MOSFETs etc channels only switch to ground, so you need a power feed, and you need the resistor in there or when the thing switches to ground the current will be massive.
....
--- End quote ---
I mean FET or IGBT input. There must be 12V square impulse already and no need for pullup.
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