I Finally Got My Pulse Motor Running Smooth with a 24-Node Magnet Array

Hook

I finally got my pulse motor running smooth with a 24-node magnet array and just one solenoid. A single reed switch fires the whole thing and it spins up after nothing more than a light touch.

Watch this experiment

I swapped the rotor to 24 magnets, kept one 12V solenoid, and used only one reed switch. At 12.3V it fires right up counterclockwise. The array is tight enough that the switch stays triggered often enough to keep accelerating even if it misses a node or two. I took it up to 20V and the speed climbed nicely. The heavier rotor takes longer to get going but once spinning it coasts for a while.

What you'll learn

You’ll see exactly how close magnet spacing helps a single reed switch drive a pulse motor, why polarity on the blue wires mattered, and how modular hot-glue mounting lets you tweak without rebuilding. We also talk about future ideas like syncing two discs off the same switch.

From the bench

The solenoid sits on a little apparatus made from a bolt, washer, and two flanges. Hot glue holds it at perfect height and I can still peel it apart later. The 24 magnets are glued to the disc but not so permanent that I can’t reuse them. Alligator clips on blue wires made polarity swaps quick once I realized I had them crossed. No clean RPM number because the meter kept jumping, but it clearly sped up between 12V and 20V and the amp draw adjusted itself.

How it works / what we changed

We cut the solenoids from two down to one and doubled the rotor magnets from 12 to 24. The closer spacing means the reed switch sees almost constant triggers instead of big gaps. That keeps the single solenoid pulsing often enough to overcome the extra weight. Polarity on the reed switch wires had been backwards on the second channel before; fixing the clips got it spinning the right way immediately. The whole thing is modular so I can move the coil half a millimeter if I want without new parts.

reed switch motor

This reed switch motor ran great on one reed switch and 24 magnets. The switch never stayed open too long because the nodes are close together. It proved a reed switch motor can be simple, reliable, and still reach decent speed once the array is dense enough.

reed switch

The reed switch is the only timing device used. One reed switch handles all 24 magnets. It picks up the field from each passing magnet and closes the circuit to the solenoid. Even if it misses a couple nodes the spacing is tight enough that it still keeps the pulse motor accelerating.

hall effect sensor

I stuck with the reed switch this time instead of switching to a hall effect sensor. The transcript doesn’t show hall effect sensor readings or wiring, so I can’t report clean data on that swap. The reed switch gave repeatable results at 12-20V without extra components.

how to build a pulse motor

To build this version, mount 24 magnets evenly on a disc, fix a 12V solenoid on a bolt-washer-flange stand at rotor height, and wire one reed switch in series with the solenoid and power supply. Start at 12V, give the rotor a light touch, and adjust solenoid distance for strongest pull without sticking. Modular hot glue makes changes easy while you learn how to build a pulse motor that actually runs.

diy pulse motor

This diy pulse motor uses off-the-shelf parts and hot glue. No soldering shown, just alligator clips and a simple stand. The 24-node array makes the diy pulse motor more forgiving than earlier two-magnet versions. It’s cheap, reusable, and proves you can get real motion without fancy drivers.

how does a pulse motor work

A pulse motor works by timing short electromagnetic pulses to push permanent magnets past the coil. Here the reed switch closes when a rotor magnet gets close, energizing the solenoid to repel or attract the next magnet. With 24 nodes the pulses come fast enough that one solenoid keeps the rotor accelerating. The closer the magnets, the smoother the hand-off between pulses.

pulse motor coil

The pulse motor coil is a 12V solenoid magnet. It’s glued to the stand but can be removed. We ran it from 12.3V up to 20V and the current draw self-adjusted. The coil gives the same “rate of lift” no matter which polarity we feed it once the wires are correct. Future plans include adding a second identical coil triggered by the same reed switch.

simple pulse motor

This is one of the simplest pulse motor designs I’ve tried: one coil, one reed switch, 24 magnets. No complicated circuits, no hall effect sensor, just power, switch, and solenoid. It starts with a finger touch and runs for a long time once spinning. The simple pulse motor still leaves plenty of parts on the bench for the next upgrade.

Builder checklist

• 24 evenly spaced magnets on rotor disc
• One 12V solenoid on adjustable stand
• Single reed switch wired in series
• 12-20V adjustable supply with current limiting
• Hot glue or modular mounts for quick changes
• Blue wires on reed switch — label or color code them
• Rotor balanced enough to coast after power off

Troubleshooting

If it won’t start, flip the reed switch wires — polarity matters. If speed seems low, move the solenoid closer but watch for magnets jumping off the unglued array. Heavy rotor needs time to accelerate; don’t expect instant RPM. If the switch stays open too long, add more magnets or tighten spacing.

Safety

Use voltages only up to what your solenoid is rated for. Keep fingers clear of spinning magnet array. Hot glue can burn — be careful when mounting. Disconnect power before moving the coil or rotor. Neodymium magnets are strong; watch for pinch hazards.

FAQ

Q: Will it run on lower voltage?

A: 12.3V started it fine but took longer to reach speed.

Q: Can I use a hall effect sensor instead?

A: Yes, but I haven’t tested it on this exact 24-node setup yet.

Q: How many magnets can one reed switch handle?

A: At least 24 if they’re close enough to keep the switch triggered often.

Q: Does coil polarity change the speed?

A: Once corrected it ran the same either way because the solenoid magnets are identical.

Related on this site

• How to Build a Pulse Motor: Complete Beginner's Guide
• Pulse Motor vs Bedini Motor: What's the Difference?
• Using a Hall Effect Sensor in Your Pulse Motor Build
• How to Wind Coils for a Pulse Motor (Step by Step)
• Pulse Motor Rotor Design: Magnets, Materials and Balance

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