Find all your DIY electronics in the MakerShed. 3D Printing, Kits, Arduino, Raspberry Pi, Books & more!

MZ_Toolbox2010.gif

This conspicuously brandless device, of Chinese manufacture, is for sale through multiple listings on Amazon, with prices ranging from $10.66 up to $20.95. The one I bought cost $14.99 with free Prime shipping, and came from CyberTech with fulfillment by Amazon itself. Besides the actual instrument, the package included a padded blue nylon zipper pouch, a four page instruction booklet in passable English, and about 24″ of 1cm-wide sparkly reflective tape.

In recent years my prejudice against Chinese tools has been proven wrong over and over again, and the DT-2234C+ is no exception. Frankly, this is a fantastic little tool, at a fantastic price, that gets the job done without breaking the bank. Is it cheap? Sure it is, in both common senses of the word. But is it worth every penny of its rock-bottom price? Again: Yes. A couple times over.

To make a measurement, the tool requires a rotating surface with a reflective area that is smaller than its non-reflective area. The special sparkly-flake tape included is nice for this purpose, but it is not strictly necessary; I got equivalent readings using common aluminum foil tape and plain white grip tape. In many cases, in fact, the tape was not necessary at all. To measure the speed of a fan, for instance, it was sufficient to simply point the meter at the spinning blades, take a reading, and divide by the number of blades.

The DT-2234C+ has a 5-digit LCD display with 3/4″ tall letters, and a range of 1 – 99,999 RPM. To 1,000 RPM it has a resolution of 0.1 RPM, and above that of 1 RPM. It claims an accuracy of ±0.05%, or to within 50 RPM at its upper limit of 99,999, which I did not have any handy means of testing. The DT-2234C+ has a minimum sampling time of 0.8 seconds, which will be higher at very low speeds (i.e. below 60 RPM), and a useful maximum range of about two feet. It also includes a memory function button that cycles through minimum, maximum, and last available readings from the last sampling period. It measures about 5×3×1″ and, with a 9V battery installed, weighs just a bit under 6 oz.

My use, so far, has consisted mainly of comparing the real speeds of various nominally-equivalent case fans so I can swap out the underperforming coolers, and for this purpose the DT-2234C+ has proven completely satisfactory. Since I haven’t been able to test its accuracy, I still hesitate to recommend it for work that requires reliable absolute readings. But for this kind of relative comparison-based testing, this little unit is a value that’s hard to beat.

Professional Digital Laser Photo Tachometer Non Contact RPM Tach

Sean Michael Ragan

I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I write for MAKE, serve as Technical Editor for MAKE magazine, and develop original DIY content for Make: Projects.


Related

Comments

  1. I’ve got one of these and they’re great little tools. Use it a lot for the lathe and mill to set/measure speed. Sometimes a little tricky to get a reliable signal – mine seems to like about a 50% black/white ratio in the signal, so make sure to cover sufficient area with the tape. The supplied tape is kinda diffusely reflecting so alignment isn’t as critical. I’ve found that sticking a small lens on the front allows you to measure a much smaller area since it focuses the laser spot.

    These are cheap enough that I’ve seen people cannibalise them and mount them permanently to a mill or lathe spindle. I opened mine up once – if I remember, it was a single large micro (possibly an ATMega) doing everything.

  2. David Rysdam says:

    I think it’s a bit disingenuous to imply that your only object to Chinese tools is the quality. Yes, they often produce some sub-par tools. But even the good tools are usually produced exploitatively (e.g. below a living wage, producing tons of pollution, etc).

    1. Sean Ragan says:

      This is a good point, and something I didn’t consider at all when I wrote this.

  3. asciimation says:

    I ended up making my own tachometer (using an Arduino of course) as I could never find one of these cheap ones that would go as high as I needed (150000 rpm) unfortunately.

    To test it at lower speeds at least try measuring a mains powered asynchronous AC motor. The speed is fixed to the mains frequency so that should be reasonably accurate I think.

  4. rocketguy1701 says:

    +1 for a build your own. Not just because of the DIY factor, but it’s an obtainable goal for the moderately electronically literate. Arduino, photo sensor and source, and some signal processing code, good to go.

  5. [...] the article Tool Review: DT-2234C+ Digital Laser Tachometer, Lindsay Wilson [...]

  6. Arshad says:

    How can I buy this product in UAE(Dubai) and what the accuracy of this product.
    Thanks

    Arshad

    1. Steve says:

      Best to buy a quality instrument for accuracy and long term reliability, See Compact Instruments web site, they have been manufacturing high quality laser tachometers for years

  7. Christopher says:

    I got one and they are really good. I had to send it to a NIST calibration lab, because we work with precision parts and calibration certificates are mandatory on every tool we use, and the NIST calibration lab issued a Certificate of Calibration. They are wonderful .