Counter Idea

[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.

[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

[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.

[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...

[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.

[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.

[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]

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.

[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.

[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.

[tonedeciple]

It works well to about 1000 rpm, then I think the switch bounce causes it to start skipping.

My counter doesn't appear to skip with the phototransistor even at full speed, which is about 2,250 rpm if my calculations are correct. I like to wind at around 1,100rpm and after about 5-6 minutes, I had a 6k Ohm humbucker bobbin with 44 awg wire. I feed the wire by hand, so I had to stop the winder a couple of times to check the coil shape.

My only concern now is the life expectancy of the motor. It gets pretty hot after 4-5 minutes, even with a fan.

[packrat99]

How about this counter? Do you think it might be a good choice regardless of the method for tripping? It's super cheap.

American Science & Surplus : Does This Count?

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. The only very minor drawback is it won't count backwards, only up. Really neat little counter. I've wound eight pickups so far and no problems with the counter at all.

Initially I tried to use an optical sensor, the counter was happy with it, but the sensor needed to be in a dark enclosure, wouldn't work with the bright lights needed to keep an eye on the wire. When I have time I'll try another type, this one was out of an old 5 1/4 disk drive, detected the notch in the discs, I guess those were pretty dark inside.

BTW, I used Jason's drawing to make a cam that runs off of the little threading indicator on the lathe, it works pretty well but is having some reliability issues, it tends to bind once in a while. It drives a rod back and forth just like his design and since it is geared to the lathe, doesn't need a separate motor. Does a pretty smooth job, I just need to beef it up a little bit.

For the price of that Schatten winder, I would consider a mini-lathe and have a tool that will do lots of things for a little more money.

[tonedeciple]

It Worked!

Thanks for all of the help from everyone. The counter does exactly what I'd hoped it would do. And, at speed faster than I can comfortably wind. Here is a link to a video. Please be aware the wiring is proto. I'll solder it to a circuit board when I get a chance.

YouTube - Winder Test

[RedHouse]

I bought a Redington 7600-731DC for $5. When I hooked up everything initially, it counted almost all the way to full speed before stalling. I don't know the actual RPM but it's a sewing machine motor with a 1-1/2" drive pulley spinning a 4" bobbin pulley.

Unfortunately I couldn't find any specs for this basic counter so some guess work went into the input requirement. The 4k7 resistor worked well with 12VDC (16.6VDC no load according to my meter).

I used your R2 equation for determining my R3. I used the values from the QRB1114 spec sheet. However, it doesn't take into consideration what the counter might need. I figure I'll start with 10k.

BTW, your site was REALLY helpful. Thanks for sharing the info. I hope to do the same eventually, though my winder won't have quite the capability as yours. Although I have an idea for an auto traverse using a servo and a servo tester circuit. But that's for another day. Can't wait to see version 3.0!

Hmm... bummer the data sheet isn't available. I just tried a few searches w/o success either.

[tonedeciple]

I Looked back over these pages in this thread but couldn't see exactly which counter you bought, there were two posts asking if a certain one was any good but I didn't see which brand/type you actually bought?.

I bought a Redington 7600-731DC for $5. When I hooked up everything initially, it counted almost all the way to full speed before stalling. I don't know the actual RPM but it's a sewing machine motor with a 1-1/2" drive pulley spinning a 4" bobbin pulley.

Unfortunately I couldn't find any specs for this basic counter so some guess work went into the input requirement. The 4k7 resistor worked well with 12VDC (16.6VDC no load according to my meter).

I used your R2 equation for determining my R3. I used the values from the QRB1114 spec sheet. However, it doesn't take into consideration what the counter might need. I figure I'll start with 10k.

BTW, your site was REALLY helpful. Thanks for sharing the info. I hope to do the same eventually, though my winder won't have quite the capability as yours. Although I have an idea for an auto traverse using a servo and a servo tester circuit. But that's for another day. Can't wait to see version 3.0!