Thread: CanePole, measuring TM RPM?

One way you could measure RPM when the motor is out of the water is with an optical tach. I've used them for RC airplane engines to adjust the carbs and I've also used one to measure fan speeds.

I ordered a tach at the parts house years ago that you could put on the end of the shaft and measure RPMs. I used it to measure rpm of combine shafts, well gear head shafts and now I use it to measure air compressor RPMs. Really handy to have. I think I paid around $30-40.

What is your goal?

Under water operation? If so, this would require a IP67 minimum rated sensor such as a magnetic hall effect sensor and a permanent magnet probably mounted in the prop hub. The hall effect would require mounting where the motor would not interfere with the sensor. Lots of things to consider, but it is an achievable project.

I don't have an idea for a tachometer, but I do run an inline ammeter on my transom mount TM. It tells me how hard the motor is working to keep the speed showing on my GPS. Would that serve the same purpose for what you are trying to accomplish?

Originally Posted by Cane Pole

What is your goal?

Under water operation? If so, this would require a IP67 minimum rated sensor such as a magnetic hall effect sensor and a permanent magnet probably mounted in the prop hub. The hall effect would require mounting where the motor would not interfere with the sensor. Lots of things to consider, but it is an achievable project.

Under water RPM measurement in a test tank is the goal. I have an Astro Flight Supper Whatt meter I'm using for V, AH, W, and WH measurement. The last thing to measure is loaded RPM.

I was hoping that when you did the other project you found that the motor already has sensor feed back. Although on the schematics I found I could not find any parts that would indicate that it had built in circuit.

Hall effect is the way I'm going now, but I also have IR parts on order as well.

I thought Superwhatt was for small motors??? Hall effect should do the trick. You will probably have to filter some of the output signal from the hall sensor.