Digital tachometer

[Eric Fahlgren]

steve ravet wrote:
> 
> This is a pretty straightforward project.  I don't completely understand
> the operation of the LM2907 frequency to voltage chip, but basically the
> coil signal is the frequency input, and this chip produces a voltage
> output that is proportional to the frequency.  The other 2 (LM3914)
> chips are LED display drivers.  They take an analog voltage in and drive
> an array of LEDs.  The higher the voltage the more LEDs are lit up.

I've been meaning to build a shift light using the above parts,
just bias the 3914 so that it turns on the first LED at, say,
6500 RPM and then adds one per 50 RPM or something like that.

The LM2907/2917 datasheet is pretty good reading.  It's got a
bunch of ideas about using it for cruise control, ABS systems,
clutch control and stuff like that.

-- 
Eric Fahlgren                            Mechanical Dynamics, Inc
efahl at adams.com                          Ann Arbor, Michigan, USA
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