Magnetic replacement for the opto fork ?

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Postby Harry Dalek » Fri Dec 30, 2011 2:07 pm

Been a bit slack on the project side due to xmas but heres a look at the Hall effect sensor working on my little scope ..

I can get a positive or negative going pulse depending which way around the Hall sensor you point at the magnet ,closer you get the larger the pulse what you see on my scope is about half it could do ,need space due to drum wobble ...Sorry using old camera today lcd screen dead so not sure what the photos like till i put it on the pc .

I am not sure what my circuits need or if it matters i recall Doms post on hes first go at the 4046 pll and it needed a pulse going the right way for it .

I am going to try this for the syncing of the large drum and another with fewer magnets for the small drum..
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Picture 202.jpg
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hall-effect-benchtest1.jpg
Not mine but this is the idea looks the same to.
hall-effect-benchtest1.jpg (31.06 KiB) Viewed 2631 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Postby Metallica Man X » Fri Dec 30, 2011 7:30 pm

I want that little scope! 8)

What types of magnets are you using for it?
I mostly lurk..don't be surprised when I actually post!
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Postby Harry Dalek » Fri Dec 30, 2011 8:03 pm

Metallica Man X wrote:I want that little scope! 8)

What types of magnets are you using for it?


Hi MM10 Yes the scopes nice its only a 1mhz but it was cheap 70 dollars or so on ebay you can see it here from a quick look but you might find a better deal if you check other sellers ..when i looked a year back seems still around the same price .
nice thing about it it charges up via the usb on my laptop no batteries to put in .
http://www.ebay.com.au/itm/ARM-DSO-Nano ... 2eacfa936b


I had toy magnets where kids make shapes they are housed in plastic the magnets are tiny but pretty strong....you can just use a magnet behind the hall sensor and have say tin strips ,it will detect that as well.

i was going to use fridge magnet plastic but the tiny magnets looked nicer :wink:
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Postby Harry Dalek » Sat Jan 07, 2012 11:37 pm

The Hall effect device i am using needed its signal to be converted from a sine wave to a square wave and to a nice signal level to be useful ,so i am using this circuit ..it works very well at all speeds of my monitor drum ...

Only thing i have changed is my sensor runs at 5v not 12 as in this circuit and i can swap via some switches pins 2 and 3 of the lm311 inputs...as some hall effect ics have the bipolar transistor as a collector output or as in mine the emitter ... i wasn't sure so saved my self some resoldering just incase .
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ex6.gif
hall effect sensor lm311 circuit
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Postby Harry Dalek » Sun Jan 15, 2012 9:47 pm

Well i had two gos at the motor control both controlled the motor but not automatic :cry:

Both circuits are a bit of mix pinched what i liked from here and there ...
The hall effect part of it works great ..the control R1 triggers the output and adjusts the pulse width...i have not showed it in the circuit but the one i have made i can flip the inputs to the Lm311...so can get a positive or negative pulse at the output .

The bistable 555 one seems to work to but i don't get auto control with the circuit no matter what the settings but all the settings do control the motor in manual adjustments..mmmmm

I also tried part of Karens 555 motor control circuit same sort of results a little less hair than i started so so far failed i will have to pick my self up dust my self down and try again ....when i am in the mood :evil:

I am thinking of ditching the 555 altogether and trying the lm311s pulse from the hall effect to start and stop the motor without worrying about control apart from that for now ...it should switch the mosfet on and off with that pulse...perhaps i should switch to a trany oh well thinking out aloud again :shock:
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sync 001.jpg
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sync 002.jpg
sync 002.jpg (73.84 KiB) Viewed 2587 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Magnetic replacement for the opto fork ?

Postby McGee2021 » Sun Feb 14, 2016 4:45 pm

This may be an older topic, but i had the idea to do this and just a few hours ago i finished putting bolts for the magnetic sync in a club disc! it was extremely shaky at first, but it only took me the short time of 45 minutes to find the screw that was misplaced. After that was all finished, i decided to go deep into the forum and came across this topic!
John Logie Baird was obviously the man who sowed the seeds but did not reap the harvest.
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Re: Magnetic replacement for the opto fork ?

Postby Harry Dalek » Mon Feb 15, 2016 3:25 pm

McGee2021 wrote:This may be an older topic, but i had the idea to do this and just a few hours ago i finished putting bolts for the magnetic sync in a club disc! it was extremely shaky at first, but it only took me the short time of 45 minutes to find the screw that was misplaced. After that was all finished, i decided to go deep into the forum and came across this topic!


My topics are never old :wink:

I tried this with tiny magnets and hall effect sensor ,i am not sure my circuit would work detecting just the metal bolts something you will have to experiment and see .

Yes a problem is adding extra weight to the disc or drum ,does not take much to make it wobble .

The opto fork is a little more elegant but hall effect sensors do work if you want to go down that road and why not :)
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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