Review on 🔢 Non-Contact Digital Tachometer RPM Tester with LCD Backlight Display - 2.5~99999 RPM Range, 50mm~500mm Distance, Rotational Speed Meter, Tacho Speedometer by Justin Vasquez

I got this non-contact speedometer after encountering a couple of situations recently where I needed to know the RPM of two motors (one electric and one gas powered), but could not measure it. Since I won't be using this that often, I didn't want to spend a lot of money on something that collects dust, but could use something fairly inexpensive and give me fairly accurate measurements. I was a bit hesitant about getting this due to some negative reviews, but overall I'm satisfied. As others have pointed out, you must try to block out the bright background light. These devices work with reflected light, and strong light that reflects what you are trying to measure can lead to some inaccurate measurements. I have tested this by measuring the RPM of several different motors and comparing it to the manufacturer's nameplate specs and each time it was within about 2%. I've tried using the included reflective tape and keeping the tach steady about 6 inches away. There was slight variation from test to test, but nothing beyond my expectations. If you want highly accurate, reproducible measurements, this speedometer is not the right choice for you, but if you need a good approximation, don't want to spend a lot of money and can live with backlighting, this thing is a good choice.