Pull-up resistor

[johnhup]

So I know this question has been beat to death, but I still understand what has to be done exactly. I am running MS-II v3 and do NOT plan on running spark control yet.

I am just trying to up the voltage from the negative end of my coil so Pin 24 can read it. Right now I am only getting 8.5 volts. Is all I have to do is add a 1k 1-watt resistor to pull the signal up?

Is this essentially what I need?

http://www.radioshack.com/product/index ... age=search


Dont resistors pull the signal down? Any clarification would be greatly appreciated.

[Bernard Fife]

johnhup,

If you are triggering off the negative side of the coil, you do not need any pull-up resistors (which are designed to take a floating signal and force it to be either high or low).

You only need the pull-up resistor if you are using points without a coil connected (and some ignition modules). If the coil is connected to the points, the coil itself provides the 'pull-up voltage' for the signal.

For more on pull-up circuits, see this: http://www.seattlerobotics.org/encoder/ ... asics.html

However, as a pull-up resistor, the ones in your link are fine, if a bit of overkill (you only need 1/8W, not 1W).

For triggering off the coil's negativew terminal, you set up as in set 50.b. here: http://www.megamanual.com/ms2/V3assemble.htm#input

Lance.

[johnhup]

I do not have points anymore. I am using a Crane XR700 with an optical sensor. For now I just want to keep this in place.

Instead of soldering my board (which I am afraid to actually), cant I just use a resistor to get the required voltage to my MS-II?

[Bernard Fife]

johnhup,

I can't claim to understand what you are trying to do, but the Hall input circuit will trigger as low as 2.8 Volts.

Lance.

[johnhup]

Well first thing I am gonna do is see how my MS-II is setup. I bought it assembled from DIY Auto Tune. My guess is its NOT setup to sense Hall signals considering my coil is putting out 8.5 volts and Pin 24 is not sensing it (although it does from the Stim).

My guess is that it IS setup to sense from the negative end of the coil. Is this the proper assumption? Would it be easier for me to just bail on my Crane and setup my MS to trigger the coil itself?

I know this requires a lot of mods which I may not be comfortable doing. I wasnt planning on having the MS manage my ignition as I am somewhat new to the world of fuel injection. I wanted to work on this later.