I've determined that running the motors at 30Hz is just too unreliable as some motors run and some do not.
I did try the primaries and secondaries in series and that works well. So I'll only need the one amp to power it all. Best thing is the current draw is under 1A according to the ammeter on the EICO power supply.
I did try the primaries and secondaries in series and that works well. So I'll only need the one amp to power it all. Best thing is the current draw is under 1A according to the ammeter on the EICO power supply.
Wouldn't it be much less hassle just by getting the right synchronous motor from get go?
It's not only transformer that don't like too low frequency, also AC motors are designed for a certain frequency, they are inductive components just like transformers and will have, all else equal, the same problem with overheating when decreasing the AC frequency too much.
Here's one example 0.8-1 rpm and 2.5-3 rpm motors.
https://www.ebay.com/itm/282845358146
another one 1.3-1.5 rpm.
https://www.ebay.com/itm/312779940620
Maybe there's a subjectively aesthetic thing with so many small balls, but one can achieve a similar amount of light spots effect just by projecting several floodlights from different angles on one single ball.
It's not only transformer that don't like too low frequency, also AC motors are designed for a certain frequency, they are inductive components just like transformers and will have, all else equal, the same problem with overheating when decreasing the AC frequency too much.
Here's one example 0.8-1 rpm and 2.5-3 rpm motors.
https://www.ebay.com/itm/282845358146
another one 1.3-1.5 rpm.
https://www.ebay.com/itm/312779940620
Maybe there's a subjectively aesthetic thing with so many small balls, but one can achieve a similar amount of light spots effect just by projecting several floodlights from different angles on one single ball.
is moreso that each ball is in a different position and would reflect the lights in different positions on the wall. Also with multiple balls some will rotate CW and others CCW.
I ran the motors during testing on 41Vrms at 40Hz and they barely got warm.
The right speed motors would be better, however it was not easy on Amazon to find some that could run at that speed with the necessary hole in the shaft in quantities greater than 1.
That said I was not exactly sure what speed would be correct when I bought the ones I did.
Plus had I done it right, I would never have thought to use a class D amplifier with a toroidal transformer to make a compact variable frequency AC supply. I'll likely further develop the concept in the future by using a higher powered amp module and a higher rated transformer. With the right module and right transformer I could have two individual outputs that are isolated from each other or one 230V output.
I ran the motors during testing on 41Vrms at 40Hz and they barely got warm.
The right speed motors would be better, however it was not easy on Amazon to find some that could run at that speed with the necessary hole in the shaft in quantities greater than 1.
That said I was not exactly sure what speed would be correct when I bought the ones I did.
Plus had I done it right, I would never have thought to use a class D amplifier with a toroidal transformer to make a compact variable frequency AC supply. I'll likely further develop the concept in the future by using a higher powered amp module and a higher rated transformer. With the right module and right transformer I could have two individual outputs that are isolated from each other or one 230V output.
I salute your widening of thought here. >>> I read that back in the 20's 30's, AC was run at 25 Hz for larger motors. I have no idea why.<<< I also don't know who came up with 60hz, but I hear that it was the lowest frequency that a light bulb wouldn't start to flicker, thus being a distraction.
This is also why I was so interested in the first PS Audio AC regenerators which the frequency could be altered to above 60 Hz all the way up to 120 Hz. Then they blew my mind with the multiwave idea for AC output of the regenerator. Better or not? Don't know, but I loved the idea of such experimentation. And yes, some transformer would make noise at certain AC frequencies. That I do remember.
This is also why I was so interested in the first PS Audio AC regenerators which the frequency could be altered to above 60 Hz all the way up to 120 Hz. Then they blew my mind with the multiwave idea for AC output of the regenerator. Better or not? Don't know, but I loved the idea of such experimentation. And yes, some transformer would make noise at certain AC frequencies. That I do remember.
I don't get why 60Hz was chosen given something like 400Hz makes transformers, motors ETC... smaller.
That is right. When I ran my TV off of the regenerator at 120 Hz, it consumed 10 watts less than at 60 Hz. I know that the PS Audio regenerator wasn't great at measuring wattage, but it gave me an idea of what was happening.
It basicly has to do with inductive losses over long distances, lower freguencies loose less power when transmitted over long distances.
Tesla came up with the 60Hz frequency. Higher frequencies are more economical at shorter distances where the cost of the losses in the distribution network are offset by the reduction or the cost of the distribution network.
Tesla came up with the 60Hz frequency. Higher frequencies are more economical at shorter distances where the cost of the losses in the distribution network are offset by the reduction or the cost of the distribution network.
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Thanks for that explanation. I have never heard of it before. I have been trying to explain AC to my son who is taking an electrical class for home construction. It can be harder than one would imagine if the person that is being taught has trouble with some of the concepts. And you don't want to tag on too much info either since it will just add confusion.
Cieling fans are synchronous motors, the voltage change changes the speed.
I still think changing the motors is a more reliable choice than a drive,
I still think changing the motors is a more reliable choice than a drive,
Looks pretty wild in that video, cool!
Got to correct myself on the floodlight, I meant using spotlight lighting up only the balls to get intenser light spots and better contrast with less background light pollution.
Ok one ball won't do it if one wants the wandering light spots going in both directions, although couple of mirrors in the corner could do the reversing...
Thinking if I'm going to get one just for the fun of it, a different type of lighting for the upcoming Christmas...? there's one 30 cm model on Thomann using lots of small 5x5 mm mirror facets that looks interesting, 39€.
https://www.thomann.de/intl/showtec_professional_mirrorball_30cm.htm
btw Aliexpress have a lot of motor options and other stuff.
@NareshBrd an AC synchronous motor rpm is dependent on the frequency.
https://en.wikipedia.org/wiki/Synchronous_motor
Got to correct myself on the floodlight, I meant using spotlight lighting up only the balls to get intenser light spots and better contrast with less background light pollution.
Ok one ball won't do it if one wants the wandering light spots going in both directions, although couple of mirrors in the corner could do the reversing...
Thinking if I'm going to get one just for the fun of it, a different type of lighting for the upcoming Christmas...? there's one 30 cm model on Thomann using lots of small 5x5 mm mirror facets that looks interesting, 39€.
https://www.thomann.de/intl/showtec_professional_mirrorball_30cm.htm
btw Aliexpress have a lot of motor options and other stuff.
@NareshBrd an AC synchronous motor rpm is dependent on the frequency.
https://en.wikipedia.org/wiki/Synchronous_motor
That is for the old fans, new energy efficient fans (with remote!) are BLDC, quite a different design, not comparable.
@NareshBrd one more time...
Synchronous motors are VAC driven and the speed is not dependent on voltage under normal use, the AC frequency decides the speed.
From Wikipedia:
"A synchronous electric motor is an AC electric motor in which, at steady state, the rotation of the shaft is synchronized with the frequency of the supply current"
NO!
Synchronous motors are VAC driven and the speed is not dependent on voltage under normal use, the AC frequency decides the speed.
From Wikipedia:
"A synchronous electric motor is an AC electric motor in which, at steady state, the rotation of the shaft is synchronized with the frequency of the supply current"
I know the AC motor theoretical speed is 120 (line freqency) / (number of poles).
Usually expressed as N = 120 (f) / (p).
Multiply by cos phi (power factor) to get actual speed.
But that does not seem to hold for cieling fans, the oldest controllers had auto transformers, then came resistors, then triacs and then capacitors as fan controllers. All were voltage controllers basically.
In any case, I think the OP is thinking of a complex solution, my answers are pointing towards a simple solution, in that our approach differs.
Usually expressed as N = 120 (f) / (p).
Multiply by cos phi (power factor) to get actual speed.
But that does not seem to hold for cieling fans, the oldest controllers had auto transformers, then came resistors, then triacs and then capacitors as fan controllers. All were voltage controllers basically.
In any case, I think the OP is thinking of a complex solution, my answers are pointing towards a simple solution, in that our approach differs.
If I could find some motors of the same exact type that are 1 RPM and silent when running I'd do it for sure as one of the reasons for slowing these down was to make them quieter.
Not sure which motor it is but I think maybe just one has an issue with the rotor as it sounds like there's an issue once per rotor revolution. If it were more than one I'm sure I'd hear it sound differently. Perhaps it's the motor that doesn't exactly start at the same minimum voltage as all the others.
Not sure which motor it is but I think maybe just one has an issue with the rotor as it sounds like there's an issue once per rotor revolution. If it were more than one I'm sure I'd hear it sound differently. Perhaps it's the motor that doesn't exactly start at the same minimum voltage as all the others.
Naresh stop fact blathering as if you stole those lines from chatgpt! :)
Ok I don't know what bush engineering is actually used in ceiling fans, but I would have guessed it's an asynchronous motor in them, at least asynchronous is much easier to change the speed using more primitive measures like resistors, triacs...
Ok I don't know what bush engineering is actually used in ceiling fans, but I would have guessed it's an asynchronous motor in them, at least asynchronous is much easier to change the speed using more primitive measures like resistors, triacs...
I learned those formulae in my second year of a graduate course in Mechanical Engineering, 1984-85...we had to learn basic electrical engineering till the third year of the four year course.
Cieling fans here were outside rotor squirrel cage motors, and slip is normal.
Now both types are available, old design is cheap, takes 55W to 65W power, works 30 years.
BLDC takes 22W, kaboom after 5 years...go figure out if extra price + replacement cost was worth the energy saved.
And with roof top solar, where in fact you are generating your own power, these calculations go hay wire. Energy price does not matter, my choice would be less complex design.
It looks like OP motors are in fact geared motors, so the control system I have described may work, the asynchronous motor is cheaper and more reliable than a more complex design, and in fact the slip can be compensated by gear selection.
So worth a try, components and regulators are easy to get.
Cieling fans here were outside rotor squirrel cage motors, and slip is normal.
Now both types are available, old design is cheap, takes 55W to 65W power, works 30 years.
BLDC takes 22W, kaboom after 5 years...go figure out if extra price + replacement cost was worth the energy saved.
And with roof top solar, where in fact you are generating your own power, these calculations go hay wire. Energy price does not matter, my choice would be less complex design.
It looks like OP motors are in fact geared motors, so the control system I have described may work, the asynchronous motor is cheaper and more reliable than a more complex design, and in fact the slip can be compensated by gear selection.
So worth a try, components and regulators are easy to get.
The spotlights are pinspots and I'm using three to cover all the mirror balls.
In order to get proper coverage with minimal light on the wall would require one spotlight per ball adjusted to where the spot is the same diameter as the ball. Given I have 13 balls that would require a lot more than three lights.
In order to get proper coverage with minimal light on the wall would require one spotlight per ball adjusted to where the spot is the same diameter as the ball. Given I have 13 balls that would require a lot more than three lights.
Usually, due to their cost-effectiveness and reliability, most standard ceiling fans use AC motors, specifically single-phase AC induction motors.
Synchronous-motor vs Induction motor
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