Joe Curry writes:
>I have examined the insides of a Spit's Smiths electronic tach and it is
>controlled by a Texas Instruments integrated circuit. This circuit is a
>custom product made specifically for Smiths to incorporate in their
>Tachs. Therefore, I doubt anybody will be able to locate any specific
>details on the function of the device not the input/output parameters.
>Therefore, the best approach is to intercept the signal going into the
>Tach and change it at that point. Instead of having 4 pulses each
>revolution, you would be getting 8. So it stands to reason that for a 4
>cyl tach to be accurate on a V8, you would have to divide the number of
>pulses coming from the coil tap by 2 and feed the remaining pulses to
>the tach.
>
>That would satisfy the requirement of the tach and not necessitate
>opening the unit at all.
>
>Dan Masters can probably whip out a circuit to supply that function in
>his sleep! Right Dan?
>
>Dan! Dan, are you listening?
>
>Regards,
>Joe
Joe et al:
I am not familiar with this vintage electric tach but I'll bet it is a
standard LM2907 F/V IC. Changing it to work on a V8 will be easy
once one figures out which component to change.
However, I am only familiar with the older tachs (60's vintage) that
don't have IC's and are obviously different than this one. If I could
have one of these to molest for about an hour I'll bet I can figure it
out.
Dave Massey
Electrical Engineer
P.S. I will be in Portland, ME
P.P.S. You could always change the numbers on the dial face. ;-)
|