LED Machine Tach For Tired Eyes

[Archangel]

Try putting a resistor from the input to ground, it sounds like it is picking up stray signals (rf?) and twist the input wires or shield them. I would try say 10K first. The displays=displays*10 would only be valid with 6 magnets.

[Sam]

Hey Joe,

I've been real busy with other things and meant to update this sooner.

The tach is working just fine, I have milled the PCB and installed one in my SC machine and it's great. I did switch to shielded wire and had to use a 1K resistor (I already had a 10K in place and that didn't work) and a .01 uf to ground.

When I get some more time I'm going to order two more of the 4 digit displays from Sure Electronics and add them to my lathe and CNC mill.

So again, I really appreciate you providing the code (I've learned from it too) and your help.

I'll post a pic of the tach in operation later. Also, if anyone would like the schematic and PCB layout from Eagle I'll provide that.

Best regards

[Archangel]

Hey Joe,

I've been real busy with other things and meant to update this sooner.

The tach is working just fine, I have milled the PCB and installed one in my SC machine and it's great. I did switch to shielded wire and had to use a 1K resistor (I already had a 10K in place and that didn't work) and a .01 uf to ground.

When I get some more time I'm going to order two more of the 4 digit displays from Sure Electronics and add them to my lathe and CNC mill.

So again, I really appreciate you providing the code (I've learned from it too) and your help.

I'll post a pic of the tach in operation later. Also, if anyone would like the schematic and PCB layout from Eagle I'll provide that.

Best regards

Hi Sam,
I appreciate the feedback! Thanks!

[Sam]

Here it is in operation ! It's doing a fine job, very happy with it.

Also a pic of the pickup coil embedded in epoxy inside a plastic tube, the magnet is epoxied to the shaft.

[DanPBP]

First, I would like to say thanks to Sam for sending me the code and the schematic.

Second, I have a question: what is the maximum RPM this circuit/code can read?

Thanks!

Daniel.

[Archangel]

First, I would like to say thanks to Sam for sending me the code and the schematic.

Second, I have a question: what is the maximum RPM this circuit/code can read?

Thanks!

Daniel.

Hi Daniel,
I added this line:

if displays > 9999 then displays = 9999

to keep the display from rolling over 9999. What use do you have for this tach? I do not think I would try it on a turbine, as it updates too slowly, but it was written for a lathe. It will go over 9999 without that line, the max is unexplored. Perhaps someone who is skilled at math could tell you. The displays can be cascaded, if you feel adventurous.

[DanPBP]

What use do you have for this tach?

I have a few brushless R/C trucks, they have an optic sensor on the transmission and I would like to read the RPM. They go up to 50.000 RPM! I'll give it a try.