Datalogging RPM signal

[A79coupe at aol.com]

Is there a way to use the signal for the tach as a source for RPM?  I'm not sure if the tach converts frequency to analog movement of the needle, or if the frequency is converted elsewhere and fed to the tach as a voltage.  Maybe we could pirate an old tach and pick up the analog voltage as an input to the data acq. module.


In a message dated Tue, 11 Dec 2001  5:10:37 PM Eastern Standard Time, Stephen Andersen <SAndersen at advan-tek.com> writes:

> Okay, I will reply to myself since after doing some research,
> I am back to DIY mode.
> 
> The LabJack USB data acq unit DOES have a counter, but none of the 
> canned software you get with it supports it at reasonable sample rates.
> 
> Someone had mentioned taking a square wave rpm signal, and turning it
> into an analog voltage using an LM2917 or somesuch and some wiring.
> Can anyone provide me with some insight (or preferably DETAILED instructions
> ;) on how to do this?
> 
> I will still need to do some programming to get maximum sample rate
> on about 6 signals, but with the built in counter, I am limited to 
> 2 samples/sec which is not nearly adequate.  With the counter and custom
> software I can probably get 16 samples/sec, but with the rpm as an analog
> voltage I can get 25 samples/second with 6 channels...
> 
> Any input?  Offline is fine if no-one on the list is interested...
> 
> Thanks,
> Steve
> 
> > Behalf Of Stephen Andersen
> > Subject: RE: Datalogging RPM signal
> > 
> > Thanks for the pointer.  I am actually thinking about buying
> > the USB logger board ($99) which has a built-in 32bit counter.
> > I can snag the rpm signal to the DME in my car and multiply it 
> > by 20 to get rpm (So I'm told).  I think with the 8 single
> > ended inputs I can record enough (including the WB) for some
> > decent tuning data...
> > 
> > Not exactly DIY though!!!
> > 
> > Thanks,
> > Steve
> > 
> ----------------------------------------------------------------------------
> To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
> in the body of a message (not the subject) to majordomo at lists.diy-efi.org


----- End of forwarded message from owner-diy_efi at diy-efi.org -----
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org