M3DVQ wrote:same sort of thing but using the microprocessor just makes it quicker to throw the circuit together then experiment in code rather than re-calculating the components for a 555 circuit
Thats one place this harry has never gone before never tried that side of electronics at all ...perhaps i am stuck in a rut i do like that 555 timer .
BTW i did see a circuit that just got all the pulses to drive one of these things with one 555 circuit looked a bit iffy to me .
Yes, I start off with something like 50 milisecond pulses and loop round decreasing the delay length by 200 or something each time until the delay is at 6666 microseconds iirc
It's all very quick and dirty code with values for the acceleration just pulled out of thin air, what seemed to work.
If you start too slow it just sits there bobbing about for ages before it starts to spin, and if you ramp up too fast it gets left behind and rolls to a stop.
It drove me nuts how fussy it was starting up and the old stepper motor problem trying to do it to quick rotten thing stops .
I wonder if i should of had a dual pot with frequency and pulse width adjustment on the same shaft as a primitive way to copy your modern ways
The disc is something like 7" diameter so it's at least doubled the diameter and only being printer card it's not very flat so adds loads of air resistance.
Oh yes i see it in your video and thanks for posting btw it every little bit of information helps ...So that was a floppy motor test .
I was going to try and just cheat and use the HD drive electronics but they cut out after a few seconds of start up .
I could not be bothered trying to track down via all that electronics what would over ride it to keep it running ....i should think if you could there might be one of 2 ways to try and control the speed ...but like you i would rather start from scratch and use my own electronics .
The heat is probably because I just have the motor blue tacked to the desk, it's not bolted to a big lump of aluminium any more - having said that I've known hard drives get uncomfortable to touch when run up constantly too.
Well thats a good reason and its some thing i never thought about much so there is a reason hard drives are in that metal case !
I would want to reduce the load on before I tried to use it for a televisor though.
As I say, I imagine a stiff metal disc inside suitable airtight enclosure would run very smoothly but that's beyond my fabrication abilities.
Why don't you just use the Hard drive's case ? and a platter you have the motor going the hard part is done...do you have a Dremel tool ? you get little tools for it like tiny grinder disks .
I have cut the case of a HD many times you could cut or just use a normal drill for a hole behind the case so you could use the platter as a Nipkow ,the image will be pretty tiny with a disk that size but with magnification it will work.
Even better a out of focus laser and you can project it to a nice size .
Before I really looked into hard disk motors I had it in my mind that a synchronous motor solves all our problems. Just generate power waveforms based off the incoming syncs and voila, the disk just has to run at the correct speed and phase.
No doubt this would be true for a motor with just six coils and a 2-pole magnet but alas using floppy drive or hard disc motors it's not as simple as all that.
Its much harder using these motors for sure but you have a leg up on the rest of us, i have not heard of any one really using them might be wrong but not on the forum any way.
What I do have as I mentioned is a floppy drive motor (which are larger) already disassembled. What I may try is removing the ring magnet and making a rotor with just two poles, then re-wiring the stator and building a six phase power supply
Oh it might work if you do it do show us,i am a bit lazy to pull motors to bits .
A lot of these motors will be gone in the years to come mechanical storage devices will soon be dead ,i expect a few years of junk shop finds then who knows .
I also suspect that the floppy motors are much more powerful than hard drives (hence the larger size) because they have to run against the drag of heads on the floppy disk unlike a hard drive motor that has almost no load to speak of.
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More than likely right there but the other does go faster ....wonder how fast floppy disks went .
I like the idea of the Hard drives just because of the speed they can do may be one day i can learn to drive them like you ,show us any other tests i find it interesting .
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.