DIGITEN 4 Digital Red LED Tachometer RPM Speed Meter + Hall Proximity Switch Magnet Sensor NPN for Lathe Conveyor Belt

We have installed more than 10 of these on Fuel/Oil delivery trucks. These are mainly expensive new delivery trucks and we must stand behind them - so far no problems at all. We have supplied our own rectangular magnets to fit our purpose better: 1/8" x 1/4" x 1/2" that we install in an existing keyway, or we mill a 1/4" keyway into an accessible part, then epoxy in place. The sensor is installed in an existing part by drilling and tapping a 12mm x 1.0 thread (tap purchased from McMaster-Carr), or we fabricate a bracket and use the double nut method. The magnet must have North & South on the big flat side, and South must be out. We buy the magnets from K&J Magnetics (Part# B842), and they have a nice little iPhone and Android app available for identifying North and South. If the app gets confused, the magnet is probably not "pole"ed correctly. The wiring colors make it less than perfect for hooking it up, but the diagram included is correct. The tach reads 1 to 1: 1 magnet sensed = 1 full turn. No setup or programming required.

I wanted a direct readout of spindle speed on my metal lathe, and this little gauge/sensor fit the bill perfectly. It uses a magnetic sensor to detect a magnet attached to the shaft spinning past it. You need to tape, glue or otherwise affix the small disc magnet to the shaft you're monitoring, so make sure you attach it securely if your machine will be spinning at high RPMs. (It claims to measure speeds up to 9,999 rpm; I'd be a little nervous about the magnet flying off under those conditions. I don't know if you could use a stainless steel (non-magnetic) strap to attach it and still have the sensor "see" the magnet, but it wasn't a concern for my usage. Just a heads-up to others who might need to use it in a higher-rpm range. (Probably better to use a reflective vs magnetic sensor for high shaft speeds...)

I've been using this on my Smithy CB-1220 XL for about three months now, and am very pleased with it's performance. It certainly beats checking the belts to see how fast I'm going. The meter is designed to snap into a rectangular opening for an almost flush mount, but I didn't have enough clearance inside the gear box, so I whipped up a little case out of an old aluminum license plate. The circuit board is exposed from the back, anyway, and it probably would end up getting splattered with oil and chips if I had mounted it directly. I added a power switch on top, and used a surplus wall wart to supply it with 12 v. The magnet must pass very close to the sensor, and the only spot available was the face of the spindle pulley, so I mounted the sensor on a bracket that can easily be swung out of the way when I need to change a belt. I used epoxy to attach the magnet. The instructions were brief but to the point. I am considering getting another unit for my Shopsmith, if I can figure out where to put the sensor. A very good item!

I tried before installed this item. Worked fine. Installed on my drill press and stopped working after third time using press. I took it off and worked for an hour trying to diagnose and only got it to work intermittently on my bench. Ordered another. It did the same thing. Sent them both back.

Spent hours milling a mount for my lathe. Installed everything correctly, paying close attention to magnet polarity, and the display does nothing but read zero. I can see the LED on the sensor blinking as the magnet goes by it so I know the sensor is working properly. Solid 12v power supply. The display electronics appear to be nothing but junk. I will contact seller but not expecting much. However review may change if this is resolved. Otherwise add me to the pile of 1 star reviews (zero stars if I could).UPDATE: After a lot of trouble shooting I found the problem. One of the 4 wires in the sensor cable (the black one) was broken inside the outer jacket. So it wasn't conducting the signal from the sensor to the board. It's pretty light wire but I'm at a loss how it got damaged *inside* the cable. Luckily the break was only about 6" back so did not have to cut off a lot but that left me with barely enough to reach where I wanted to mount the enclosure. Regardless it appears to be working now. -1 star for no markings on magnet to indicate south pole. -1 star for the bad wire. Seller did reply though and promised to make good if it didn't work. +1 star. 4 stars now.

Installed this on my knee mill. I now can see the exact spindle speed. It was super easy to install and wire.

Used this for a one cylinder engine because it is difficult and expensive to find a good tach for a one cylinder. I have tried those inductive mini tachs that use a wire to wrap around the spark plug wire. They are not reliable and not worth installing. This works great. I installed on the end of the crank with a bolt and couple of washers. Grind a slot in the washers for the magnet and use a little epoxy extra security once you know you have the magnet installed with the correct side facing the pickup. I did have to fabricate a bracket to hold the pickup sensor ( not a big deal). It actually reads the rpm changes faster and more accurately than those little mini tachs. I am going to install another one on my other tractor this fall.

I didn't trust the analog tach on my sailboat diesel motor so I bought this digital LED Hall Effect Proximity Sensor to check. Installation was very direct and simple. The only problem I had was discovering the hard way that the sensor was polarity sensitive. The kit came with a small disc magnet and I had a 50/50 chance of mounting it correctly. There was nothing in the directions accompanying the kit indicating magnetic polarity was important and not just proximity to the magnetic field. Once I discovered my error, it worked perfectly. I can rely on this device and my analog tach was goofy. The only thing I would have preferred was that the LED display was water proof.