Melting Motors: 120 Volts vs Homemade Lego Motor

Comments · 345

• MR

  @MrPeplonski · 2 years ago · pinned

  You might be able to reduce your arcing by connecting a 150V bidirectional Zener diode or TVS diode (Transient voltage suppressor) between your windings.<br><br>The cause of this arcing is the stored energy in the magnetic field (E = 0.5*L*I^2) that is present when your coils are energized. As soon as the contacts of your commutator open, the magnetic field collapses trying to keep up the current that was flowing before. To achieve this, the coil has to build a high voltage than can bridge the pretty high dielectric strength (3kV/mm) of the air gap causing arcing.<br><br>The voltage created by the coil is equal to:<br>V = -L * (di/dt)<br>Where as L represents the inductance of your coil and di/dt is the change of current. Since opening the contacts abruptly means a very high change of current (di/dt), the voltage created by the coil will rise tremendously.<br><br>If you connect a bidirectional Zener Diode that will start conducting at 150V, it will clamp the produced voltage down to that 150V and gives a safe path for the coil to release its energy.<br><br>However the higher the voltage of the coil, the faster it can release all its stored energy and be sooner ready to accept the current in the reversed direction. I never tried this myself and I dont know how long the diode will last or die out after a couple of revolutions because of overheating, but I think it might be worth a shot

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• DO

  @doctortwilight · 2 years ago

  The beeping of that power supply gave me flashbacks of those overvoltage toy destruction vidoes

  346

• AS

  @ASE-FAS · 2 years ago

  The motor never ran at 120v, the powersupply was current limited so the highest voltage it ran at was about 50v

  106

• IS

  @isaac-g4u2h · 2 years ago

  To avoid contacts melting you can use several wires to make a &quot;brush&quot;. This distributes current better. To have more efficiency you can split the same amount of power among more sets of coils, four or six. This way power is only used on coils that are closest to the magnet, producing more torque for the same voltage.

  130

• TH

  @themajasticcreature · 2 years ago

  You actually never got to 120v because you hit the power limit of 3.2amps wayyy before 120v. Powersupply limits current by lowering the voltage. You need to make a less power hungry motor for 120v or get a more powerful power supply

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• RE

  @RedShift5 · 2 years ago

  Try three phase induction motors, you don&apos;t need a commutator that can burn out with those ones.

  49

• TR

  @Trex0Pol · 2 years ago

  You actually never ran it at 120V. Since the power supply was maxing at 3,2 amps, it switched to CC (Constant Current) instead of CV (constant voltage). Once you get to the current limit, the voltage starts to drop. We can actually prove this by a simple calculation. Since power equals voltage times current, if it ran at 120V with 3,2 amps, we would get to 384W, but it was only at 150W with 3,2 amps, which means the voltage was at around 46V.<br><br>Also, to improve the brushes, why not try using the copper sheet as brushes, too? It will increase the surface area.

  108

• GO

  @Goofy.goober0695 · 1 year ago

  <a href="https://www.youtube.com/watch?v=yahZO9fIvWA&amp;t=588">9:48</a> “woha what an incredible breeze”😭

  8

• CU

  @cuf_ · 2 years ago (edited)

  you never hit 120v, not even half of that. your 3.2a supply was going into constant current mode causing the voltage to dip. if you actually ran it at 120v it would draw probably near 10a or 1.2 kilowatts. also a thicker wire would run it at even lower power and voltage because it decreases the resistance that in return increases the current demand that your supply cant provide, thus it has to lower the voltage.

  21

• AB

  @Abhinava_Playz_YT · 1 year ago

  <a href="https://www.youtube.com/watch?v=yahZO9fIvWA&amp;t=313">5:13</a><br>Nobody should ask face reveal after watching this part

  3

• TH

  @Thatonebusgeek · 1 year ago

  <a href="https://www.youtube.com/watch?v=yahZO9fIvWA&amp;t=34">0:34</a> it sounds like an engine idling I love it

  12

• MY

  @MyNathanking · 1 year ago

  <a href="https://www.youtube.com/watch?v=yahZO9fIvWA&amp;t=474">7:54</a>: &nbsp;That&apos;s how to make a two-pole commutator. &nbsp;The two halves are clearly split this time around.

  1