schmitz@hpscdc.scd.hp.com (John Schmitz) (08/29/90)
Does anybody out there have any information on "Wiegand wires"? They are some sort of magnetic sensor that could be used for counting much like a reed switch or hall effect device. I think I saw articles on these wires about 10 years ago. I may well have the spelling wrong. Thanks schmitz@scd.hp.com hplabs!hpscdc!schmitz
mmm@cup.portal.com (Mark Robert Thorson) (08/30/90)
If I'm not mistaken, these are merely iron wires that have axial twists put in them (by mechanically twisting the wire). They were once proposed as a medium for encoding the magnetic stripe of credit cards. Their advantage would be that the magnetic anomalies created by the twists could not be erased and re-recorded, unlike conventional magnetic recording media. As far as I know, this proposal never got anywhere.
macminn@powertool.crd.ge.com (Stephen R MacMinn) (08/31/90)
John Schmitz writes: >Does anybody out there have any information on "Wiegand wires"? I've had some experience with Wiegand sensors. They're a variety of magnetic sensor that makes use of a material property called the Wiegand effect. I'm not sure of the details (though I could dig some up), but the essence of the matter is that when the magnetic field passing through the sensor changes polarity, the sensor puts out a fixed magnitude voltage pulse (the ones I saw were 2V). The pulse magnitude is independent of the rate at which the polarity change occurs. The sensors we bought have the added benefit of working to temperatures of 200 degrees C, beyond the range of semiconductor based (Hall) sensors. I've got more information. If you're interested, you can send me E-mail (macminn@crd.ge.com).
paul@hpldola.HP.COM (Paul Bame) (09/25/90)
> If I'm not mistaken, these are merely iron wires that have axial twists > put in them (by mechanically twisting the wire). They were once proposed > as a medium for encoding the magnetic stripe of credit cards. Speaking of credit cards, why don't we use bar codes or some other optical method rather than magnetic? Seems like it would be more reliable. "Gee, I guess it happened when I left my eelskin wallet in the MRI room :-)" -Paul "Spice is the Variety of Life" paul@hpldola.hp.com N0KCL
myers@hpfcdj.HP.COM (Bob Myers) (09/25/90)
>Speaking of credit cards, why don't we use bar codes or some other optical >method rather than magnetic? Seems like it would be more reliable. > >"Gee, I guess it happened when I left my eelskin wallet in the MRI room :-)" Yeah, or didja ever stay at a hotel that has those new magnetic-card-reader locks? Ever try to explain to the front desk clerk that your card won't work anymore, because you spent the day at a monitor manufacturer and had occasion to do some degaussing? (You know the routine: turn on the coil, wave it around the tube, slowly back off, sweep the coil down near your pants pocket, realize what you've done, yell "Aw, SHIT!!!!!.....":-)) Bob Myers KC0EW HP Graphics Tech. Div.| Opinions expressed here are not Ft. Collins, Colorado | those of my employer or any other myers@fc.hp.com | sentient life-form on this planet.
phil@brahms.amd.com (Phil Ngai) (09/27/90)
In article <17660116@hpfcdj.HP.COM> myers@hpfcdj.HP.COM (Bob Myers) writes: |Yeah, or didja ever stay at a hotel that has those new magnetic-card-reader |locks? Ever try to explain to the front desk clerk that your card won't work |anymore, because you spent the day at a monitor manufacturer and had occasion Far more effective to just tell them their darn locks are broken and you can't get into the room you paid money for. Why assume any responsibility for it? -- Phil Ngai, phil@amd.com {uunet,decwrl,ucbvax}!amdcad!phil Freedom is dead, long live privacy!
jra@lawday.Dayton.NCR.COM (John.Ackermann@Dayton.NCR.COM) (09/27/90)
In article <10960034@hpldola.HP.COM> paul@hpldola.HP.COM (Paul Bame) writes: >Speaking of credit cards, why don't we use bar codes or some other optical >method rather than magnetic? Seems like it would be more reliable. > ATM cards use a magnetic stripe because the machines actually write transaction info on on the stripe. ATMs do this so that you can't go from machine to machine (some of which may not be online to your bank) and withdraw in excess of your limit. Each transaction decrements the daily limit value stored on the stripe. -- John R. Ackermann, Jr. (513) 445-2966 Law Department, NCR Corporation VoicePlus 622-2966 Dayton, Ohio John.Ackermann@Dayton.NCR.COM ***** Amateur Radio: ag9v@n8acv or ag9v@ag9v.AMPR.ORG *****
jad@dayton.UUCP (J. Deters) (10/03/90)
> Article <480@lawday.Dayton.NCR.COM> From: jra@lawday.Dayton.NCR.COM (John.Ackermann@Dayton.NCR.COM) >ATM cards use a magnetic stripe because the machines actually write transaction >info on on the stripe. ATMs do this so that you can't go from machine to >machine (some of which may not be online to your bank) and withdraw in excess >of your limit. Each transaction decrements the daily limit value stored >on the stripe. This is a used-to-was idea that was kicked around when ATMs were first proposed. They considered keeping your balance on the card so that an offline ATM could still fork over the cash. Due to the ease-of-fraud that would be built into such a system, it was abandoned early on. Track 3 is still read/write, but is not used for any financial information. I believe that there is a proposal underway to write your "credit rating" on the third track so that you (a cardholder) could have personal floor limits more suited to your spending habits. The cost of a credit transaction is primarily the phone call. We have it easy: SNA links to Visa/Mastercard, AmEx, and Discover. Not every Mom&Pop, Inc. has that luxury, and is forced to make a phone call for every transaction over a $40 floor limit. If your card were encoded to indicate that you paid your bills on time every month last year, spent an average of $75 per transaction, maybe 10 transactions per month, they could encode a "local" floor limit of $100. The Point-Of-Sale device wouldn't even make a phone call for charges less than that. The reason Visa might consider such a system is that they would save 100 phone calls a year per customer described above. Let's say that one phone call costs Visa $.50. Assume the risk of fraud and/or bad debts in the customer category described above is less than $50.00/year That translates into savings in reduced equipment capacity required, reduced staffing of the WATS lines, fewer WATS lines, all while not adversely affecting their bad debt losses. (This information was published recently in Retail Info Systems News.) -j, "...but I know my credit limit is supposed to be $100,000..." -- J. Deters Ask me about my PS/2. // INTERNET: jad@dayton.DHDSC.MN.ORG Then, // UUCP: ...!bungia!dayton!jad ask me about my Amiga! \\ // ICBM: 44^58'36"N by 93^16'12"W \X/