I Finally Got My Hall Effect Controller Pulse Motor Running (Reed Switch)

Hook

I fired up the power supply, the rotor started spinning the opposite way I expected, and suddenly the whole thing became a working gyro. This reverse layout with magnets outside pulse and electromagnetic coils the rotor is weirdly satisfying.

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The motor is a three-magnet, three-coil setup. Bifilar coils sit fixed in the center. The rotor carries three large permanent magnets on the outside. A reed switch glued to the base handles timing. Two copper rings act like a floating commutator — one positive in the center, one negative on the outer ring. Wires hang down from the top flange and brush the rings while the rotor spins.

What you'll learn

You’ll see how a magnets-outside layout creates a clear gyro effect, why the rotor direction reversed on its own, and how combining drive and trigger strands into the same 2630 bifilar coils keeps things simple. We also test what happens when voltage climbs from 24 V to 35 V.

From the bench

Everything was thrown together in one afternoon. The base holds three bifilar coils wired 2630-2630-2630 with the trigger strands rolled into the drive. No separate hall effect controller board — just a reed switch glued in place. The top flange drops onto the shaft, carrying three large magnets spaced 120°. Two copper rings sit below the flange: center ring positive, outer ring negative. Power supply connects through the reed switch, then to the coils, and dumps to ground. The whole rotor spins counterclockwise once power is applied.

How it works / what we changed

I guessed the rotation direction right before the first test. When I tried to spin the entire assembly one way, the rotor immediately reversed and took off the other direction. That was the gyro effect kicking in. The positive contact is now the center ring and the negative is the outside ring of copper. The middle contact stays constant while the outer ring shows small dips, but overall it maintains good connection. Lifting the top off reveals the rotor still spinning the same way even after power is cut.

magnets outside pulse

The phrase magnets outside pulse describes exactly what we built. Three large permanent magnets ride on the outer edge of the rotor while the electromagnetic coils sit fixed in the middle. This layout produces a visible gyro top effect — the rotor spins one direction while the upper part seems to want to precess the other way. At 24 V it starts instantly; at 35 V it flies. The outside magnet placement also makes the whole thing look like a weird spinning top that somehow powers itself in both directions at once.

rotor permanent magnets

The rotor permanent magnets are three strong neodymium pieces spaced 120° apart on the outer rim of the spinning disc. They pass over the fixed inner coils and create the main magnetic interaction. Because they sit on the outside instead of the usual inside rotor, the gyro effect becomes obvious. The motor reversed direction the moment I tried to force it the other way, proving the rotor permanent magnets were dictating the stable spin direction. Even after power is cut you can still see the rotor permanent magnets keep turning for a bit.

electromagnetic coils the rotor

In this build the electromagnetic coils the rotor never actually touch the rotor — they sit stationary in the center while the magnets fly past. Three bifilar coils are wired in series with the trigger strands folded into the drive strands (2630-2630-2630). Power flows from the reed switch through the coils and then to ground. The electromagnetic coils the rotor are therefore the fixed stator, not something attached to the spinning part. This is the reverse of most pulse motors and is why I call it a reverse gyro.

Builder checklist

• Glue reed switch in exact position so magnets trigger it cleanly
• Wire bifilar coils 2630-2630-2630 with trigger integrated
• Set center ring as positive, outer ring as negative
• Space three rotor permanent magnets exactly 120°
• Drop top flange so hanging wires brush the copper rings
• Start at 24 V, increase slowly to 35 V while watching for vibration

Troubleshooting

If the rotor hesitates, check that the reed switch is glued at the right angle to catch every magnet pass. If contact sparks a lot, make sure the outer negative ring is smooth and the hanging wires have good tension. At higher voltage the speed is limited by how the power is distributed through the combined trigger/drive windings — that’s expected. If it spins the wrong way, the magnet polarity or coil winding direction is probably flipped.

Safety

Use a current-limited power supply. Keep fingers clear of the spinning rotor with its strong magnets. The copper rings and hanging wires can spark at higher voltages so wear eye protection. Do not leave the motor unattended while powered. The gyro effect can cause unexpected direction changes so hold the base firmly during first tests.

FAQ

Q: Are you using a hall effect controller?

A: No — this version uses a glued reed switch even though the inspiration came from Noah and Peter’s hall effect 2.0 work.

Q: Why does it spin backwards?

A: The magnets outside pulse layout creates a gyro effect that forces the rotor to reverse when you try to spin it the other way.

Q: How fast does it go?

A: It runs nicely at 24 V and gets faster at 35 V, but the combined windings limit top speed. Still faster than my previous motor.

Q: Can I swap in a real hall effect sensor later?

A: Yes — the credit to Noah and Peter is exactly for that future upgrade path.

Related on this site

• How to Build a Pulse Motor: Parts, Coil Placement & First Spin
• Pulse Motor Rotor Design: Magnets, Materials and Balance
• Using a Hall Effect Sensor in Your Pulse Motor Build
• I Finally Got My Pulse Motor Running (Reed Switch)
• Donut Magnets — Outside Poles & Motion

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