Counter Idea

[Joe Gwinn]

I just bought four of these and they work great, they are internal powered just like a watch, it never turns off. It counts pulses applied to one of the rear terminals, reset is done by applying a positive voltage to the other terminal. I use a 9 volt battery switched through a reed switch to the counter input (5-30 volts). You can't beat these for 5 bucks. I use it on my mini-lathe winder with a reed switch just above the chuck and a small magnet stuck to the chuck. It works well to about 1000 rpm, then I think the switch bounce causes it to start skipping.

A small capacitor and resistor in series across the reed switch contacts plus a series resistor in the feed line from the 9 volt battery may control the contact bounce. The resistor in the 9-volt line is sized to recharge the capacitor in a few milliseconds (long enough to bridge over the bounces), and the resistor in series with the capacitor is sized to limit the current to whatever the reed-switch contacts will take.

[packrat99]

Thanks - I didn't phrase things properly, I think the spring action of the reed switch limits how fast it can respond, that's what I meant to say. I did try to clean it up with a cap, but it didn't help. However, it counts fast enough for the speed at which I have been winding.

[RedHouse]

Thanks - I didn't phrase things properly, I think the spring action of the reed switch limits how fast it can respond, that's what I meant to say. I did try to clean it up with a cap, but it didn't help. However, it counts fast enough for the speed at which I have been winding.

Yes it will, and the reed switch will fatigue after a while.
(it's just a piece of metal bending/back at a rapid rate)

Do try to go with an optic switch when you can.

[Joe Gwinn]

Thanks - I didn't phrase things properly, I think the spring action of the reed switch limits how fast it can respond, that's what I meant to say. I did try to clean it up with a cap, but it didn't help. However, it counts fast enough for the speed at which I have been winding.

The physically smaller reed switches resonate above 1 KHz, and so are able to keep up. You may need an oscilloscope to see what's going on.

Reed switches run at low current typically have a lifetime in the millions of cycles, which is many pickups worth. If we assume each pickup is 10,000 turns, that's 10^6/10^4, or 100 pickups per million cycles.

Optical is better; the tradeoff is complexity. The counter can power a reed switch, whereas optical needs a power source for the LED.

[RedHouse]

The physically smaller reed switches resonate above 1 KHz, and so are able to keep up. You may need an oscilloscope to see what's going on.

Reed switches run at low current typically have a lifetime in the millions of cycles, which is many pickups worth. If we assume each pickup is 10,000 turns, that's 10^6/10^4, or 100 pickups per million cycles.

Optical is better; the tradeoff is complexity. The counter can power a reed switch, whereas optical needs a power source for the LED.

It's a piece of metal bending, it does/will fatigue.

[tonedeciple]

It's a piece of metal bending, it does/will fatigue.

Yeah, those dollar store window alarm reed switches aren't designed to handle 5,000 turns at the speeds we typically wind. In fact, my first attempt at such a counter lasted only 6 bobbins before it began to fail.

[David Schwab]

Another option is proximity switches. That's how I was going to trigger my Durant counter on the winder I was going to build.

But now I'm doing the CNC winder....

Now I have a box of proxy switches I don't need...

[Joe Gwinn]

It's a piece of metal bending, it does/will fatigue.

Yes, but the reed switch designer has considerable control over when this will happen. In other words, not all reed switches have the same design lifetimes, and it's worthwhile to read the datasheet. Generally, long-life switches will be long and thin, so the strain in the reeds is below the fatigue limit, so what wears out is the contact coating. What's best for long life is rhodium; gold is terrible.

[RedHouse]

Yes, but the reed switch designer has considerable control over when this will happen. In other words, not all reed switches have the same design lifetimes, and it's worthwhile to read the datasheet. Generally, long-life switches will be long and thin, so the strain in the reeds is below the fatigue limit, so what wears out is the contact coating. What's best for long life is rhodium; gold is terrible.

Suit yourself but I wouldn't bother with reed switches when opto's are available for well under $10, in fact the surplus electronics store near me has those OpTek units like I used in the Winder-2 project for like $2/ea which is even cheaper than many reed switches:

But to each, his own Joe. Live and let live

[tonedeciple]

Suit yourself but I wouldn't bother with reed switches when opto's are available for well under $10

And if you own a business, you can get samples for free from a lot of manufacturers.