LED Machine Tach For Tired Eyes

[mister_e]

Seems they have pretty nice stuff there, probably not suitable for mass production, but interesting and cheap.

[Sam]

Well the code provided by Joe works great now. I really appreciate Joe posting this and then taking the time to help me get it working. I have three machines that I really need tach's on, a spincaster, a cnc mill, and a lathe and this display and Joe's code fits the application perfectly.

The display I got from Sure Electronics was this one. It was only $14.00 delivered and is quite bright.

I'm in the process of setting up a hall effect sensor as the pickup and it should work fine for this.

Thanks again Joe,

Sam

[Sam]

I guess I was a bit too quick to think that my hall sensor implementation would be simple. Here's the hall effect sensor I have, it works great as a switch, such as for a cell phone lid or laptop lid switch or some application like that, as it's recommended for.

But it just doesn't appear to be able to switch quickly enough. Can anyone recommend or have experience with one that is better suited for a tachometer yet inexpensive ?

Thanks

[jderson]

Hi Sam-

I have been using the AFL series parts from NVE (DigiKey). They work good, but kind of expensive ($9 U.S.) The datasheet says bandwidth is 100khz., but I have only run them at several hundred R.P.M.

[Sam]

Hi Sam-

I have been using the AFL series parts from NVE (DigiKey). They work good, but kind of expensive ($9 U.S.) The datasheet says bandwidth is 100khz., but I have only run them at several hundred R.P.M.

Thanks jderson, I'll take a look at those. I'm also considering trying IR emitter/detector with a reflective stripe. But would prefer the hall sensor method.

Thanks again,

Sam

[Archangel]

Thanks jderson, I'll take a look at those. I'm also considering trying IR emitter/detector with a reflective stripe. But would prefer the hall sensor method.

Thanks again,

Sam

So many ways Sam, Hall effect, plain old coil and magnet glued on the shaft **, spinning disk with holes and opto, old relucter and pickup from car distributor, heck even points for low rpm application, all can be directly driven or run off an idler belt / pulley setup, who cares how many sensor triggers per revolution, you can tweak it in the software to do any math required. On my lathe I plan to put a small belt to the "encoder" from the headstock so I do not have to hassle modifying the spindle. Oh I thought of another one, if your spinning shaft has a nut spinning too aim a small magnet at the nut and a coil of wire at it at about a 60degree angle, might work as a reluctor. Or a spinning gear . . .
** Note: Remember those aftermarket Cruise Control units from the 1980s?

[mister_e]

Yup, we used to install some magnet on the drive shaft when there was no existing VSS source. been a long long time