Here’s another POV project for you. It’s pretty big, at 1 meter in diameter, not quite as large as the stupidly huge one. What is interesting about this display is that it has a dual motor set up. The original motor didn’t quite have the power to get the display up to the required speed. A second one was added as the shaft of the rotor. Yes, one motor is actually spinning another motor that is spinning the display. Well, it’s hard to tell from the description. The original motor might be completely unused, but left in place.
“A second one was added as the shaft of the rotor. Yes, one motor is actually spinning another motor that is spinning the display.”
although this is a nice idea, it’s unfortunately not the way physics work. so what’s more likely the case is that the motor being spinned around is actually standing still, producing just enough friction to take the led blade with it.
Noticed that it was missing a sentence at the end. It looks like the original motor may be non functional in the final design.
“discription”? oh gosh…
I think he left the original motor in there because of the built in rotary encoder that he needed.
@tulcod:
“although this is a nice idea, it’s unfortunately not the way physics work. so what’s more likely the case is that the motor being spinned around is actually standing still, producing just enough friction to take the led blade with it.”
could you elaborate on this? specifically in what way you think physics works?
@jim:
the force excited on the “second” motor (the one being spinned around) does not decrease by the addition of the first motor, assuming the same speed. for a higher speed, the drag excited on the second motor (being spinned around) only increases, so it would need a higher power output, which it didn’t get.
just a cool way of decreasing the number of LED’s required for a normal panel.
To put it simple: To join two forces, they need to be in parallel, not series.
So, it would’ve worked if two motors put force on a central cog or something.
You guys just don’t get it. The first (blue) motor is attached to the stationary part by its axis. That way, I could access its rotary encoder from the moving part. It proved not powerful enough, so I added a stronger motor to drive the second motor’s housing, which is actually the moving part. The original motor is not getting any power.
BTW, this is a very, very old project. It’s been 8 years.
@Tulcod:
That’s not right – it is possible to increase the rotary speed by rotating one motor with another. The key point is that second motor’s shaft is turning relative to the second motor’s housing – so it has a speed of, say ‘s2’. If the housing is rotating at ‘s1’ relative to zero, then the second shaft is spinning at s1+s2.
The other thing you said, about friction – depends on the type of motor. An unpowered permanent-magnet motor will induce a force that opposes the driving force, which would equate to wasted power in the system, like you said. However, the losses in a system where both motors were powered would be minimal. They would be very wasteful as the started up, as the motors would ‘slip’, but after that they would eventually stablise.
Yo dawg, I heord you like motors, so I put a motor on your motor so you can spin while you spin.
/obligatory
//facepalm
You guys :[
Read before complaining about stuff that don’t need complaining e.g. the second motor.
@Lucas:
That was actually highly appropriate. It made my day anyway.
Now someone just need sto make a pov binary watch so we can all be jealous.
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For how long ? That’s the question !
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[fuzzcraft] already mentioned it, but this project is really old, i remember stumbling across the web page years ago.
@ blogkungfuhist
lol
@Jim:
agreed. if one motor stands still while trying to drive the propeller it will indeed not have a good time trying to survive the nonstop orgasm of current.