Contact-less tachometer counts up to 99kRPM

There may be some situations when it is hard to use a tachometer only because it is impossible to read revolutions per minute mechanically. The only way is to read RPM without touching rotating shaft.



This great design was constructed by Ibrahim Kamal who used an IR signal to transmit and receive it reflected from reflective stripe fixed to rotating shaft. Device is controlled by AT89S52 microcontroller which counts reflected pulses and displays value on LCD. RPM counting algorithm uses last three times between pulses and this way constantly gives instant RPM value. RPM meter consists of two parts: microcontroller board and IR proximity sensor connected to microcontroller board via simple 4 wire cable. Project files are available for download in a single zip.

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  1. I did a much “hackier” version with an Arduino that might be of interest to some. It certainly isn’t as versatile and accurate as this, but it is a good starting point for experimentation:

  2. zip files are not available .. maybe you could reupload them

  3. can you upload the zip file agaibn please! thanks or email me it on

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