555 EFI again...

[Walter Petermann]

> ... The voltage across
> > > the capacitor rises in an exponential fashion, whereas we require that
> > > the voltage rises in a linear ramp.  This can be acheived by using a
> > > constant current source to charge the cap.
> ..
> > > Chris Morriss
> 
> Clare Snyder wrote:
> > How do we implement this - modification to the referenced circuit?
> 
Clare,
I have added a current source to the rc circuit. It's not great, but it 
keeps the extra op amp free. Will keep that to make an input for rpm.

 Walter

http://www.brokersys.com/~corsaro/wiring_diagrams/555fe_isrc.htm