Bouncefree switch question.

[jpm83]

Hi I'm in process of building a winder for my self to start making some pickups for myself.
My question is that will this boucefree switch idea work on calculator or "step counter" (thing that counts your steps when you're walking), that is presented in this page. http://europa.spaceports.com/%7Efishbake/ot1/ot.htm

Janne

[R.G.]

Why don't you use an optical interruptor? No mass, no reversal of direction of a mass, and so no bounce.

[jpm83]

Thank's for answering. The reed relay thing just would be the most "easy" for me to put in this winder I'm making, but I'll have to keep that optical thing on my mind too.

[Joe Gwinn]

Thanks for answering. The reed relay thing just would be the most "easy" for me to put in this winder I'm making, but I'll have to keep that optical thing on my mind too.

With reed switches, the usual problem is that the on time is too small a faction of the circle, causing the pulsewidth to become too narrow to count reliably at high speeds.

For example, a simply flying magnet will have an on time (duty cycle) of 1%, so if the counter requires 10 millisecond or wider pulses, the max speed is 60 rpm. People have had this problem with reed switches.

The solution is to arrange the magnetic circuit so that the on time is at least 25% of a rotation.

[DrStrangelove]

With reed switches, the usual problem is that the on time is too small a faction of the circle, causing the pulsewidth to become too narrow to count reliably at high speeds.

The solution is to arrange the magnetic circuit so that the on time is at least 25% of a rotation.

Alternatively, use a Hall Effect switch from Allegro. They aren't much more complicated than a reed switch.

The A3245 isn't picky about magnet orientation or supply voltage.
http://www.allegromicro.com/en/Produ...3245/index.asp

-drh

[Joe Gwinn]

Alternatively, use a Hall Effect switch from Allegro. They aren't much more complicated than a reed switch.

True, but they require power, whereas a reed switch can be connected directly to a battery-powered counter such as a CUB3. If one has power, one can as well use the photo interrupter approach.

The simple way to arrange the flying-magnet cum reed switch is to have two parallel mild steel plates between which the magnet swings, the magnet being oriented perpendicular to the plates and parallel to the rotation axis, with the reed switch bridged between the two plates. The plates can be made from electric-box covers from a hardware store.

If the magnet is between the plates between 1/2 and 1/3 of a turn, the counter will work to ~2000 rpm, at least in theory. At very high speeds, it may be useful to make some radial slits in the plate to reduce eddy currents. Radial slits are on lines that pass through the location of the reed switch. I would not bother cutting the slits unless there is an observed problem, though.

[RedHouse]

Why don't you use an optical interruptor? No mass, no reversal of direction of a mass, and so no bounce.

+1

After you get a handle on how to use them, there really is no substitute.

[chevalij]

I have a basic schematic for wiring up the H21L0B opto switch if anybody wants it. I just use a divider network and a 9V wall wart to power it.

[David Schwab]

Here's how the Schatten does the optical counter. The optical devises are on the back wall.

[Joe Gwinn]

Here's how the Schatten does the optical counter. [Image deleted.] The optical devices are on the back wall.

It strikes me that the small hole in the black disk may cause the pulsewidth to be too small, although counters vary and one assumes that Schatten picked a suitable counter.

[RedHouse]

...It strikes me that the small hole in the black disk may cause the pulsewidth to be too small....

Yes, that was a concern of mine when I made my 2nd winder, so I made sure to have like at least 25% of the optical wheel transparent. The CUB counters (I use) utilize a Schmidt trigger input so I don't have to worry at all about too wide a pulse.

Here's my micro-blog on it: http://users.isp.com/brad_anne/winder.htm

BTW, I too can provide some schem'a for the optical interruptor unit I used in mine (OPTEK OPB380) just ping me if you need it. In fact if I get any more than one inquiry I'll put it on my micro-blog. (my new term for pictorial info pages)

[RedHouse]

Here's how the Schatten does the optical counter. The optical devises are on the back wall.

Hey David, off-topic here, but do you take off-line questions about Bass pickups?
(email)

[jpm83]

I think that i will use that hall effect switch on this winder. Would this swich be usable for winder? http://pdf1.alldatasheet.com/datashe...UGN3130LL.html
UGN3130.
Thanks for all the replies.

Janne

[jpm83]

Or would this be better? http://pdf1.alldatasheet.com/datashe.../TLE4935L.html

Janne

[David Schwab]

Hey David, off-topic here, but do you take off-line questions about Bass pickups?
(email)

Sure. You can either email me or send me a PM via this forum.