Digital Photo Laser Handheld Tachometer - $25.00 (plus postage)
Measures the rotational speed with a visible LED light beam
High intensity class II laser measures from 2.5 - 99,999 RPM
Extra large 5-digit LCD display, high accuracy of +/- 0.05%
Auto zero adjustment, stores last, minimum, and maximum readings
Here is another tool from the depths of our bilges onboard OSIRIS.
I got this tool because I was frustrated at not really knowing what was the "real" rpm's of the diesel engine.
The electric rpm guage that is part of the instrument console just wasn't very reliable and at idle rpm's jumped all over the place.
Additionally, when installing a high output alternator I needed to know what was the rpm's of the alternator so I could match the output amperes to the various engine rpms.
And there were many other times when you just want to really know what is what and when it comes to rotational speed - rpm - this little device very nicely eliminates the guess work and the need to resort to a dull pencil and mathematics. You just read the numbers on the little screen.
The device comes in a nice neat black box/case with an instruction pamphlet and a strip of reflective adhesive tape. To use the tachometer you affix a small piece of the reflective tape to the surface of what you want to measure like the pulley on the front of the engine.
Then when the engine is on and rotating you depress and hold the "measure" button on the side of the tachometer until you get a stable reading on the screen. Then release the "measure" button.
Depressing the "Memory" button on the front of the tachometer will cause the measured rpms to display in the order of first the "max" rpm; then another press will get the "min" rpm; and the final press will give you the "Last" rpm just before you released the "measure" button.
Powered by 4 x AAA Batteries (not included). Size : 8" x 3" x 1.5"
(This particular unit does not contain the additional mechanical measuring wheel mentioned in the instruction manual.)