Review on 🔷 DIGITEN 4 Digital LED Tachometer RPM Speed Meter with Hall Proximity Switch Sensor NPN in Blue by Sean Maples

Originally posted on a RED device, it probably won't have a "Confirmed Purchase" tag. Blue is the one I bought. For some reason the photos are not showing in the other post? I've seen a lot of questions about this total station so I decided to review it and hopefully answer some of the many questions but before I go too far mostly remember the old adage "you get what you pay for". This is a very inexpensive device that you could pay a few $100 for if it were lab-grade electronics. So keep that in mind when you buy one. . This will be a 2x72 belt sander made up primarily of a couple of used treadmills. I use a treadmill motor to drive the belt and I needed to know the speed of the belt so I figured a tachometer on the motor shaft would give me a good idea of the speed of the belt. I bought this cheap set and am very happy with it. If it had wiring instructions (photo attached) I would give it 5 stars. One star off because I had to find out for myself. I power it with a 9V DC-AC-DC converter that plugs into an outlet, one of the small devices that power our calculators and laptops, charge our phones, etc. They are commonly referred to as "WALL WARTS". I've thrown about 20 things in a box over the years. This one is "rated" for 9 VDC at 210 mA (amp-km). Some photos show it up to two meters and a speedometer kit attached. If you look closely at the meters you will see that the figure reads 11.87 VDC, the open circuit voltage for this WW (wall wart) is 13.2 DC from my measurements. Electronics experts will understand this, but for non-electronics folks the voltage drops when the power supply is charging, according to the datasheet if it had a 210mA load it would drop to 9VDC. Which brings me to the actual load, look at the old analog meter, it's set at 60 milliamps and reading about half the scale or about 30 milliamps. That means the tach kit will only charge the WW to 30mA by just reducing the output voltage to 11.87 VDC. Based on that, the minimum WW rating could be as low as 9 VDC at 50 mA, which is really very low. The bottom line here is that just about any WW 6-9VDC will get the job done. I say 6-9 and not 8-15 because of the small load the tack puts on the WW PSU. I say start with 6 because I have four WW 6VDC and they all have an open circuit voltage of 8VDC or more. One of my 12V WWs has an open circuit voltage of 17.8VDC. You don't want to put as much voltage on this device. See the photos for answers to other questions such as: B. for wiring. In conclusion, I recommend this and similarly colored tachymeters for non-critical applications. Great inexpensive material for a hobby. Edit: For some reason not all photos are showing for this post, although I can see the thumbnails in this editing session. However, they are shown in an almost identical post for the RED version of this wheelbarrow. Check it out if you don't see the schematic in this post.