[Vwdiesel] Diesel Tachometer in an older VW

[Tony and Lillie]

There is actually an adjustment on this tach, but it still says 3000 RPM at 
idle. It goes from 3000 to 7000 at idle, but I think that adjustment is just 
for the fine tuning of the range. Either that, or it's for the different 
cylinders available on the 90's. They had 4-cyl's, 5-cyl's, and 6-cyl's. So, 
that adjustment doesn't have enough in it.

I like the idea of the TI Rate Multiplier. That may very well be the way I 
go. I also found Jake's site with the write-up of how he made it work. I'll 
be taking pics and put an article in the KB when I finally find and complete 
a solution to this problem. For now, I'm just happy to have it back on the 
road. The speedo is the next order of business.

Thanks again,
Tony
----- Original Message ----- 
Subject: Re: [Vwdiesel] Diesel Tachometer in an older VW


>I was investigating creating a divider (having an electronics degree) to
> solve this problem and found a 'programmable' divider on Texas Instruments
> site CD4527B (CMOS BCD Rate Multiplier) which is and old design really,
> called a 'rate multiplier' but can do fractions (dividing) of a frequency. 
> I
> wish I had a gasser instrument cluster to try it on.
> But then I started thinking, if VW was smart they would have made the
> instrument cluster programmable to begin with, so depending on different
> trannies gear ratios (speedo pulses) and engines cylinders (ign.
> pulses) they could have a single part manufactured and make a setting for 
> a
> particular car.
> Maybe someone on the list has a inst. cluster and has a electronic
> background or a friend with electronics experience that could look the
> cluster over and see if the is a 'programmable' part plug-in chip or dip
> switches (or wire jumper set) on the cluster board.
>
> Brian