Review on 🔋 Yeeco AC Frequency Meter - Digital LED Display Panel, Mini Frequency Tester for AC 20-500V 20-75Hz - Hertz Meter Counter in Green Red Yellow (3PCS) by Oscar Thompson

Nice, bright display, the photo doesn't convey it. Works great on city electricity. The description says it runs at 75Hz, but when I hooked it up to my alternator I got readings that jumped between 375 and 450 (at constant rpm), so I think the frequency is above 75Hz. Not suitable for running a typical backup generator set, probably due to over-voltages from the automatic voltage regulator, but I think I read something about this with the seller before buying, so I didn't deduct a single star. I decided to take a chance, I think I need to develop a new app for these cool little devices.