Tachometer Calibration

Wav files for Tachometer calibration

from the column for your engine type choose an RPM somewhere near the middle RPMs

download the Wav file from that line in the table (right click and "save link as")

connect power and ground to the Tachometer ( use a battery or regulated power supply, not a charger)

connect the red calibration lead clip to the tachometer input

connect the black calibration lead clip to the tachometer case

connect the other end of the cable to your laptop, computer, iPhone etc.

No other cables should be connected .. eg no connection to the car ignition system

With the tachometer in the orientation it will be in the car

Play the wav file at full volume, (if using windows media player, select "loop" to play the file continuously)

the tachometer should respond

adjust the tachometer to show the appropriate RPM in the table


Frequency 4 Cyl 5Cyl 6Cyl 8Cyl 10Cyl 12Cyl
  100Hz 3000 2400 2000 1500 1200 1000
  200Hz 6000 4800 4000 3000 2400 2000
  300Hz 9000 7200 6000 4500 3600 3000
  400Hz   9600 8000 6000 4800 4000
  500Hz     10000 7500 6000 5000
  600Hz       9000 7200 6000


For low revving engines a 50Hz tone may be useful;  50Hz file

Sometimes it is useful to use an alternating  100Hz and 200Hz file

and by special request !  100Hz, 200Hz and 300Hz file

The latest instructions for installing our RVI to RVC board can be found here

An FAQ with further useful information can be found here


If the tachometer does not respond to playing the wav file then you can try the following

increase the volume on the device playing the file

try with various combinations of bass and treble (tone)

try switching the red and black calibration wire connectors.

the sensitivity of every board is tested using a standard signal, so don't give up,

if you cannot get the tachometer to move, try another audio device,



Keep an eye out for the few tachometers that have the red and black wires switched..

the board will try to make the needle move the wrong way..

If this happens, you will need to switch the thin red and black wires



Videos of the Internal Conversion on YouTube
RVI to RVC 1 dismantling the tacho
RVI to RVC 2 fitting the circuit board
RVI to RVC 3 powering up the board
RVI to RVC 4 calibrating
RVI to RVC 5 alternative connections


the external resistor mentioned in the videos is no longer required


Checking calibration with an acoustic tachometer

For calibration on the car, a simple (although not always successful) alternative to a rolling road is to use a smartphone acoustic tachometer app.
We have tried two android apps (We have no affiliation or connection with these products) with varying degrees of success !

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