Belkin Regulator PRO Silver 650VA UPS Teardown

This is a short teardown of the smallest UPS I have yet found thrown out. The Belkin Regulator PRO Silver UPS 650VA (model F6C650-SER-SB) uses the battery type CSB HC1221W which has been discontinued. If not obvious, my daughter helped …

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Victron Energie Atlas Combi 12V/800W Battery Charger/Inverter Teardown

I do a teardown and test of a Victron Energie Atlas Combi 12-800. It is a combined battery charger and 230VAC inverter. The battery charger of the Atlas Combi is suitable for a 230 VAC, (50 Hz) mains voltage. The …

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Yearly Battery Check – My 2021 New Year Resolution.

My 2021 New Year resolution is to do annual battery checks on all my battery powered instruments. I found batteries as old as 13 years over expiration date that had also started to leak, but much less defective batteries than …

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Canon Ixus V70 Hack with CHDK for High Speed Photography

Turn your old compact Canon camera into a high speed photography camera with Canon Hack Development Kit I bypass the battery pack and make the camera run on a power supply, as the CHDK software takes a lot of CPU …

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APC RS-1000 UPS Teardown

A teardown of a APC RS-1000 UPS, a run down of the current paths in the system. Data on the unit:

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750W Victron Solar Project – 60 Days Performance – Part 4

In part 4 I take a look at the efficiency and look at the performance over the last 60 days. If you want to see how all this was built, check out the part 1, part 2 and part 3 …

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750W Victron Solar Project – Power wall and 8 days performance – Part 3

In part 3 I test the setup with all 3 panels connected and look at the performance over the last 8 days. In part 1 you can see all the parts I pieced together and in part 2 there is …

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750W Victron Solar Project – All 3 panels test – Part 2

In part 2 I test the setup with all 3 panels connected, it all consists of: 3x 250W solar panels 1x Victron SmartSolar 100|30 MPPT battery charger 2x Norbatt 12V 150Ah batteries 1x 750W 24VDC to 230VAC inverter

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750 Watt Solar Project – Test Setup – Part 1

In part 1 I give a walk-through of my test setup, charging and the Victron app to control the charger over blue-tooth, it all consists of:3x 250W solar panels1x Victron SmartSolar 100|30 MPPT battery charger2x Norbatt 12V 150Ah batteries1x 750W …

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Homopolar motor

What is a homopolar motor?

The name means that the electrical polarity of the motor never changes. The axis of the rotating part of the motor is parallel to the magnetic field from the permanent magnet. Lorentz forces is what makes the motor turn, a conductor conducting current through a magnetic field will respond to a external magnetic field and will gain velocity in what direction the fields happen to be aligned. The hand rule applies here.

This motor is restricted to a single turn coil which limits it to small voltages around a couple of Volts and it has a low torque.

Homopolar generator

The homopolar motor will also work as a generator if we remove the battery and apply the motion to the rotating disc. It is only capable of supplying a couple of Volts but at very high currents, generators can be put in series for higher voltages. Very large homopolar generators are used for high current short circuit testing.


Warning: this motor operates at high speeds up to 6000 RPM, the screw can at any time loose contact and fly through the air.



Michael Faraday demonstrated this motor concept in 1821 at the Royal Institution in London. The homopolar motor is the first electrical motor to be built. His construction was a large and crude concept that he himself describes as “This apparatus may be much reduced in size, and made very much more delicate and sensible.”

The original article in Quarterly Journal of Science:


How can you perform this experiment yourself?

You will need the following four items to make this experiment.

  • 1x 1.5 Volt battery. I use a AA battery
  • 1x iron wood screw.
  • 1x piece of copper wire.
  • 1x round neodymium disc magnet.

Follow these four steps to make it work.

  1. Place the head of the screw in the centre of the magnet.
  2. The screw must be touching the positive terminal of the battery. Sides of the battery are insulated.
  3. Hold the wire with your finger against the negative pole terminal of the battery.
  4. Gently let the other end of the wire touch the side of magnet, completing the circuit.
  5. Watch as the magnet and screw starts to spin faster and faster.



A quick experiment that can be made from common household items. It is a simple practical demonstration of the basic electro magnetic theory, that would help many understand the force around a wire easier.

Published August 4, 2011. Updated October 31, 2021.