Gallery, Projects and General > The Design Shop
Coax indicator design
kwackers:
Just to throw something completely different into the mix.
I was contemplating making something like this and so I'm fairly interested in the issues and design.
What I considered doing though to make the whole thing small was to get a magnet to move and use a coil as a pickup (or the other way round). This could be used to drive a small meter. It auto zeroes when not moving (since we're only interested in the 'wobble') and could in theory provide the 'multiplication' required to overcome the mechanical 'loss' particularly when long arms are used.
It's not got much further than an idea, but I thought I'd bung it up here in case it had legs or could give someone a nudge in another direction.
ken572:
Bill,
That is a really cool idea/concept. Time to build a proto-type,
and make a video clip of it in test use. :thumbup: :clap:
Ken.
picclock:
I like the magnet idea.
A multipole magnet with north and south horizontal close to a stereo cassette recorder read head might be an easy way to implement it. Just tuning for minimum output would work. By connecting the heads out of phase the balance between north/south fields would be very precise.
Somthing to think about :coffee:
picclock
BillTodd:
--- Quote from: kwackers on November 05, 2010, 08:33:55 AM ---Just to throw something completely different into the mix.
I was contemplating making something like this and so I'm fairly interested in the issues and design.
What I considered doing though to make the whole thing small was to get a magnet to move and use a coil as a pickup (or the other way round). This could be used to drive a small meter. It auto zeroes when not moving (since we're only interested in the 'wobble') and could in theory provide the 'multiplication' required to overcome the mechanical 'loss' particularly when long arms are used.
It's not got much further than an idea, but I thought I'd bung it up here in case it had legs or could give someone a nudge in another direction.
--- End quote ---
I had wondered about using a magnet to couple the rotating vertical movement of the rocker to a stationary lever but rejected it as too compliant.
--- Quote from: picclock ---I like the magnet idea.
A multipole magnet with north and south horizontal close to a stereo cassette recorder read head might be an easy way to implement it. Just tuning for minimum output would work. By connecting the heads out of phase the balance between north/south fields would be very precise.
Somthing to think abou
--- End quote ---
Yes.
The snag with all magnetic sensors like coils is their sensitivity to stray fields (hum from motors or just the rotating mass of iron coupling to any static magnetic field. I suppose if the parts could be shielded it might work
Or (getting excited now :LOL:) if there were four coils, stationary and located on the X and Y axis. With two magnets on the rocker, as they passed the coils, each magnet would induce a different current in the two coils (varying with distance). it would be possible to synchronously rectify the outputs of the two pairs of coils to give an X & Y error read out. Thoughts?
Bluechip:
Some more 'orrible thoughts ... if you want to convert a wobble to a indicator ( meter ? ), you're making a seismometer. :thumbup:
Some 30 yrs ago I made ' variable capacitor / pll / amp / meter contraption that actually worked.
The cap was two bits of PCB, one bit stationary, t'other attached to a weighted beam. When it moved, capacitance varied, osc. freq. likewise, pll outputs a voltage proportional to freq. and so to the amp.
Maybe easier to screen than inductors/ magnets. Maybe not.
Dave BC
PS .... don't ask how I configured the pll, 'cos I can't remember. Only time I've ever used one :scratch:
It was not a 4046 IIRC. NE xxxx ?? But it is probably possible with a 4046. Suppose they're much the same.
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