View Full Version : Experimenters only

03-23-2007, 12:23 PM
In my day job I work for a company that sells automatic meter reading equipment. I am about to recycle about 100 protpotype boards which have magnetically actuated normally open glass enclosed reed switches. Our testing shows closure is consistant within .002 when a standard magnet approches the switch. These could be used for home brew prox switches, probe (something I am working on) or ???
I hate to see good stuff becoming landfill, and will send a few to anyone interested, no cost. Drop me an email. If I get too many requests I may ask for postage.


03-23-2007, 02:02 PM
Jim you have mail.

03-24-2007, 11:51 AM

04-26-2007, 03:13 PM
I finally got packages in the mail. If you are expecting and get nothing, contact me in about a week.

Things you might like to know:

These switches require a user supplied magnet to work. Best allignment is a rod magnet with N and S poles parallel to the switch axis. North can be either end. Opening and closing distance should be consistant with small tolerance, but larger magnets will close the switch at larger distance. Magnet and switch can approch by motion along the axis of the switch or perpendicular to the axis of the switch. Closure distance will be consistant but different.

These and any mechanical switch will bounce briefly when changing state. I do not know if ShopBot has a debounce routine on their inputs. A backup and slow second approch as in the ZZero routine should deal with this.

These and most other switches will have Hysterisis. You will need to back up a bit to achieve an open switch after seeing a closure.

The Kovar leads are solderable, and are part of the switch magnetics. Switches will still work but will have slightly different charactoristics if the leads are trimmed. Soldered leads should be motion restricted near the switch. Motion of the wires will very slightly change the switch close distance by influencing the magnetic fields.