Altennative Magnetic Sensor Mod

[Pixl]

For you guys working on modified sensors, you might experiment with this. I had read that there is a magnetic disc found in many IDE hard discs that have multiple magnetic fields embedded with in. Here is a magnetic disc I pulled from an old HD.



I sprinkled iron filings on a paper.



When I placed the paper over the HD disc, 10 embeded magnetic fields were revealed.



These might work with a magnetic reed switch.

 

[richyrich]

Is there any one type/year/brand of HD that has these discs like only old? Say is it 9"; sized; or around smaller HD's too Spinning drives that is? Most that need mo.ds have a small space requirement, that is birdview h/h would need it may work in modified space; like 4.5 inches.

 

[Pixl]

This came out of a Western Digital 3.5" drive. I took apart a smaller 2.5" Fuji drive from a laptop, but it did not have the magnet disk.

 

[Lone Gunman]

I made a couple of these back a few years ago for the Von Weis movers I have on my two 10ft dishes. The magnets I used are some of those high power ones I got from an electronics supply and I mounted them in alternating polarity. They work fine but I didn't see any specific advantage to the increased count they produce over the 8 magnet one that was originally in them. To improve accuracy I really need to move the actuator to dish mounting point out further from the dish pivot point. Have a bracket made to do that, just been too hot to mess with it now.

 

[Magic Static]

I have a VonWeis that had an optical sensor and converted it to a magnet wheel and reed switch. I used a 6 mag wheel and the double counting switch technique to give me 60 counts per inch on a 5 pitch ball screw.

 

[Pixl]

I have a VonWeis that had an optical sensor and converted it to a magnet wheel and reed switch.

Magic, or anyone else with the optical sensor. I have a Von Weis that the sensor quit working after a lightning storm. The optics were still working, but there is a driver transistor that shorted out. I pulled a NPN transistor from an old circuit board and got it working again. The stock optical disc has six slots and seems to work just fine with a V-box.
I am interested to see that someone might experiment with a HD disc for this service.

 

[Magic Static]

I am interested to see that someone might experiment with a HD disc for this service.

While I don't immediately see a use for the disc, I would like to know one thing about it, if you could check. Are all 10 fields the same polarization or do they alternate poles. Alternating poles might trip the right reed switch. If they are all the same, it won't work a reed switch because they are too close together from what I see in the iron filings.

 

[Pixl]

Magic,

I checked out HD disc with a compass. It clearly alternates from N to S when rotated.