Levitating Motor
- Thread starter Ken I
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Ken
At the point of winding the coils. I'm using #36 wire and shooting for 15 ohms. Your spread sheet shows 106 turns. I wound 100 turns and measured 36.8 ohms. From that I assume I should wind only 50 turns.
What do you think???
At the point of winding the coils. I'm using #36 wire and shooting for 15 ohms. Your spread sheet shows 106 turns. I wound 100 turns and measured 36.8 ohms. From that I assume I should wind only 50 turns.
What do you think???
rustyknife
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Gld-
The wire selection, number of turns and resistance are all depen.dent on the output of your solar cells and how much room you have to wrap. You will want to measure the voltage and amperage of each of the cells, in full sunlight.
What your trying to accomplish is to make the strongest electromagnet possible.
This website does a good job towards the middle and end of explaining electromagnet calculations:
http://www.coolmagnetman.com/magdcem.htm
basically electromagnets strength are calculated by the amount of current flowing through the wire, and by the number of turns.
So say you have a solar cell that puts out .568 volts and .610 amps in full sun.
by rearranging ohms law, we know that if we divide our voltage by our resistance we can calculate the flow of current, or amps through the wire.
so we go to a chart that lists all the wire gauge sizes like so:
http://amasci.com/tesla/wire1.html
There we can see the diameters and resistances and then I just start playing with numbers.
Lets say it takes 12" of wire to make one turn of a coil on my motor. (you should measure yours and use that number)
if i use a 28 gauge wire and can make 200ft of wire fit at 200 turns then I can look at the resistance value chart and with a little math I know there should be around 12.8 ohms in that coil,
If I divide .568 by 12.8 ohms....I get a dismal .044 amps. My solar cell puts out .610 amps, but I can't use them because I have made a poor selection of wire. .044x200 turns= 8.8 ampere turns or the strength of the magnet. Remember thats in full sunlight. so if you want to make run inside, you must have the strongest magnet possible from your solar cells.
Well we need less resistance so lets go to a bigger wire.
Lets say I wrap a 23 gauge wire around it, but I can only get 120 turns or so physically on my motor. 120 feet of wire. The resistance calculated out for this one is 2.44 ohms for the 120 feet.
.568/2.44= .232 amps x120 turns= 27.9 ampere turns, much stronger then before, but still not flowing up to where my cells are at.
This is where choosing higher voltage cells or wiring them in series for higher voltage helps. The higher voltage will let you use smaller wire and more turns.
Just keep playing with the number till you find one that suits your needs. Hopefully I haven't confused you. But you should have all the info in those two links that will lead you to success.
The wire selection, number of turns and resistance are all depen.dent on the output of your solar cells and how much room you have to wrap. You will want to measure the voltage and amperage of each of the cells, in full sunlight.
What your trying to accomplish is to make the strongest electromagnet possible.
This website does a good job towards the middle and end of explaining electromagnet calculations:
http://www.coolmagnetman.com/magdcem.htm
basically electromagnets strength are calculated by the amount of current flowing through the wire, and by the number of turns.
So say you have a solar cell that puts out .568 volts and .610 amps in full sun.
by rearranging ohms law, we know that if we divide our voltage by our resistance we can calculate the flow of current, or amps through the wire.
so we go to a chart that lists all the wire gauge sizes like so:
http://amasci.com/tesla/wire1.html
There we can see the diameters and resistances and then I just start playing with numbers.
Lets say it takes 12" of wire to make one turn of a coil on my motor. (you should measure yours and use that number)
if i use a 28 gauge wire and can make 200ft of wire fit at 200 turns then I can look at the resistance value chart and with a little math I know there should be around 12.8 ohms in that coil,
If I divide .568 by 12.8 ohms....I get a dismal .044 amps. My solar cell puts out .610 amps, but I can't use them because I have made a poor selection of wire. .044x200 turns= 8.8 ampere turns or the strength of the magnet. Remember thats in full sunlight. so if you want to make run inside, you must have the strongest magnet possible from your solar cells.
Well we need less resistance so lets go to a bigger wire.
Lets say I wrap a 23 gauge wire around it, but I can only get 120 turns or so physically on my motor. 120 feet of wire. The resistance calculated out for this one is 2.44 ohms for the 120 feet.
.568/2.44= .232 amps x120 turns= 27.9 ampere turns, much stronger then before, but still not flowing up to where my cells are at.
This is where choosing higher voltage cells or wiring them in series for higher voltage helps. The higher voltage will let you use smaller wire and more turns.
Just keep playing with the number till you find one that suits your needs. Hopefully I haven't confused you. But you should have all the info in those two links that will lead you to success.
gld,
Rustyknife is spot on - max current occurs at an impeadance match - but watch out for the actual conditions you would be running under - my testing of a limited range of photocells seems that full rating will only occur in direct vertical summer sun.
As regards the spreadsheet - something seems off - no sure what. If you dialled in all the correct values then I suspect your wire might be thinner than #36.
Either way I wouldn't lose too much sleep these things are pretty tollerant.
P.S. I have been trying to get full non-contact levitation using servo / feedback circuits but even here old Earnshaw is giving me a hard time.
Playing footsie with the laws of physics take patience.
Regards,
Ken
Rustyknife is spot on - max current occurs at an impeadance match - but watch out for the actual conditions you would be running under - my testing of a limited range of photocells seems that full rating will only occur in direct vertical summer sun.
As regards the spreadsheet - something seems off - no sure what. If you dialled in all the correct values then I suspect your wire might be thinner than #36.
Either way I wouldn't lose too much sleep these things are pretty tollerant.
P.S. I have been trying to get full non-contact levitation using servo / feedback circuits but even here old Earnshaw is giving me a hard time.
Playing footsie with the laws of physics take patience.
Regards,
Ken
Well I finially got mine to run. Ended up with 60 turns of wire, and my wire is # 36... Coils measured 20.4 and 19.6 ohms. My rotor has the wobbles so the end stops are just touching the ends. Balancing this is a royal pita. I cnc'd a clear plastic base and plan to show it at Zanesville.
rustyknife
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Balance is a royal PITA. Not only do you have to worry about the balance of the rotor, the power level of the solar cells contribute to a dynamic balance. I had one solar cell on my first one that was very weak compared to the rest and did not have the same level of power at low levels, caused quite a wobble
Yeah - Rustyknife - unequal solar cells do give it the wobbles - I also found that out - when I was given a bunch of cells I was horrified by the variability in output - fortunately I was given so many I was able to make up a matched set.
Also mechanical ballance is about the magnetic centre line which is never quite the same as its physical centre - this means that once you have ballanced the rotor, you can't move the rotor magnets (ie take it apart and reassemble) so if you do have to take it apart - mark the angular position of the magnet to get it back to the same place.
Ken
Also mechanical ballance is about the magnetic centre line which is never quite the same as its physical centre - this means that once you have ballanced the rotor, you can't move the rotor magnets (ie take it apart and reassemble) so if you do have to take it apart - mark the angular position of the magnet to get it back to the same place.
Ken
