Datalogging RPM signal

[Tomas J. Sokorai Sch.]

Hi, I'm writing an opensource program to plot HP curves and monitor/log 
engine RPMs. I'm using a voltage divider to pick the 12V signal from the coil 
input. The input is recorded with my soundcard using the Line input.
I'm having troubles with trying to figure out how to count the spikes, 
because the signal I get is VERY far from a square wave :). And with my 
ignition, when the RPM goes up, the signal amplitude goes DOWN ....so no 
static treshold for counting spikes :/.
The input for the HP measurement I'm using is the tire diameter, gearbox 
ratio, differencial ratio, vehicle weight, nr. of cylinders (for calculating 
each 360 deg. engine turn)
The formulas I'm working with are based on converting the engine rotations in 
distance traveled. Then I apply the basic motion formulas to calculate speed, 
acceleration, force, work and power.
I'm calculating the drag from the desacceleration... I know this isn't 
completely right, but I don't know the Cd of my truck, so I wanted to have a 
rough estimate.
My program is in it's very beggining stages, anyone wants to participate in 
such project?.  It's being programmed under Linux with KDE gui.


Tomas Sokorai.


On Thursday 20 December 2001 20:05, Steve.Flanagan at VerizonWireless.com wrote:
> Glen
>
> Do you have any incite as to the physics being used with that device.
>
> What inputs are used to calculate the HP / TQ numbers?  And how is the drag
> from wind added to the equation.
>
> How about the actual vs corrected values on the web site, what is used to
> calculate them?
>
> I would love to see some of the formulas being used.  I am sure its all
> basic physics, but I am not sure where those books are anymore.  Think
> there in a box at my parents place?
>
> Steve
>
> -----Original Message-----
> From: Glen Beard [mailto:gbeard1 at nycap.rr.com]
> Sent: Tuesday, December 18, 2001 10:47 PM
> To: diy_efi at diy-efi.org
> Subject: Re: Datalogging RPM signal
>
> "Porter, Bill" wrote:
> > Follow instructions at this link
> > http://www.charm.net/~mchaney/homedyno/homedyno.htm#inst to make an
> > inductive pick up.  The link uses the pick up to drive the MIC input on
>
> your
>
> > laptop.  From here I'm unsure of how to configure to time sync with the
>
> wide
>
> > band and the DataQ software.  I haven't used the DataQ yet to see if it
>
> will
>
> > accept outside signals.  Don't know what type of voltage you will get off
>
> of
>
> > pick up to drive DataQ directly
>
> As a matter of fact, I bought that thing from him and made
> up my own pickup just like he described about 3 years ago.
> (His software works pretty well as long as the info you feed
> it isn't too far off.)  I haven't measured the output
> spikes, but they are easily viewable on the waveform
> editor.  It also shows quite a bit of noise.
>
> Is there an IC out there to use these triggers to build a
> nice 0-5V square wave for use as an input to the DAQ?

----- End of forwarded message from owner-diy_efi at diy-efi.org -----
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