It seems the tach question has been covered a lot but I was unable to find any information on creating a tach made of several LED's. I'm building a small dash to be placed on the steering wheel of a racecar. I'd like to use 5-10 LED's to progressively light up as the RPM's increase for a small yet effective tach for the driver. I was wondering how I will light each LED based on the freq of the tach signal. Any assistance or circuit schematics would be greatly appreciated.
A row of 5-10 LED's will give you a very poor tacho readout. You really want a LED for every 100RPM or so, that's 60 for 6000RPM.
Driving these is easy by using the 2917 tacho chip which converts the tacho frequency to a varying voltage. This you can feed to a cascaded 3914 LED bar driver or just a simple meter with a tach scale.
I built one of these LED tachos years ago, still have it somewhere but the car I have now already has a tacho.