Very simple digital tach circuit diagram?

1) This won't necessarily be a 'very simple' circuit. 2) You'll probably get better responses from sci.electronics.basics for this question.

Good luck anyhow.

-phaeton

My suggestion...just buy one...there are suppliers for gauges of just about any type.

A digital tach doesnt really make much sense, IMHO, in this sort of application. An analog, or simulated analog, is much more comfortable in most cases.

Problem is that the display can't be larger than 1.5"

or may have something.

...and you ned a tach on a GM van with a V6 why?

So I can judge engine speed in relation to when the transmission shifts and also in relation to a vibration problem I'm having.

Four digits would probably mean a display of 1000s, 100s, 10s and units. Although one of those digits could be used to display 50 rpm.

Here's an assembled circuit that includes a diagram online. As others have noted it isn't simple. So unless you have a desire to build one from scratch, you might want to consider a finished project. The project notes indicate that rpm's displayed below 100 be unstable. The numbers would be bouncing up and down quite a bit and would be very hard to read. Resolution to 100 would follow current practice for analog tachs.

You also might try a Google search. I found several home-brew kits. The one above looked most promising.