Howdy!

I'm anything but well versed in electronics, but I do have a basic understanding of ....basic stuff. So, I figured I'd solicit those of you who know a lot more than me to help me with a problem...hopefully.

I've built a digital counter for the purpose of tallying rotations on my metal lathe. The reason I need to do that is that I wind guitar pickups, and the tonal characteristics of a pickup are determined in large part to the number of wraps of magnet wire.

I made the counter itself from a digital pedometer by removing the mechanical pendulum, and soldering leads from the necessary points on the PCB and connecting the leads to a micro reed switch.

I placed a strong NIB magnet on the rotating pickup bobbin holder, and by means of a home made holder, placed the reed switch in close proximity to the rotating piece.

It works, but only until I get to around 150 RPM, then it starts skipping or missing turns. I figured that out by using my built-in digital lathe tachometer and a stop watch to calculate an expected number of turns over a 60 second period at various RPM's.

I'm guessing that the problem is contact "bounce", but I have no idea how to overcome that with a micro reed switch. I've heard that adding a small value capacitor to the circuit might help, but I don't know where to place it in the circuit (in series or parallel, before or after the switch, etc.), the value.

Could it be rel;ated to the pedometer's ability to keep up? If so, any ideas on what might be a better device to use? Maybe a calculator?

I need the counter to keep up at 400 RPM's ideally (the fastest I can safely guide 42 guage wire without it breaking).

Any help or advice is GREATLY appreciated!

Thanks

 

Hello,

Did you ever think of a hall-sensor?
This is a magnetic sensitive resistor.
See this page of the EDUCYPEDIA for more info on these sensors.
http://www.educypedia.be/electronics/sensorshall.htm
I think there ara sensors that can go upto 3000 RPM.

Greetings,
Bertus

 

Thanks.

Nope, never heard of those, and I wouldn't know how to use it in this application.

Thanks again, though!

 

Your pedometer won't be able to keep up. Digi-Key has a nice little counter, part #RCL03 that should work for you. It has an internal battery, and costs $32.40. They have a line of counters.

 

Hello,

Here is an aplication note how to use a hall effect sensor.

Greetings,
Bertus

 

Thanks to both of you!

Guess I'll cut my losses and buy the counter. Maybe use a Hall Effect sensor for a switch if the dry reed switch doesn't work out with the store bought counter.

 

Be aware that those counters are either/or. But your reed switch should keep up ok.

 

Either / or? Not sure what you mean.