Simple Circuit Reed Switch Runs My Six Magnet Rotor to 1033 RPM

Hook

I spent the day going back to basics with a simple circuit reed switch on a pulse motor and ended up clocking my six magnet rotor at 1033 RPM. Nothing fancy, just a reed, a coil, and a variable power supply. The whole thing is a documentary for me as much as it is for you.

Watch this experiment

I started at 9.2 volts and 100 mA. The rotor was already spinning nicely on a plain bearing flange—no maglev today. I kept increasing voltage and watched the current and RPM climb. At 15 V it was pulling about 200 mA and really whipping. By 18 V it hit 0.2 A, then I grabbed the tac meter.

What you'll learn

You’ll see exactly how a simple circuit reed switch behaves when you sweep voltage on a six-magnet monopolar rotor. I logged the RPM climb, the point where extra volts gave diminishing returns, and the audible change in speed with every tenth of a volt near the top end.

From the bench

Coil is 666 turns of 20-gauge wire wired in 180° series. Rotor has six magnets, monopolar. It sits on an upside-down flange that fits the bearing groove. Power supply max is 25 V. I ran it up to just over 20 V and the current went past 3 A at the high end. The reed switch kept things simple and smooth.

How it works / what we changed

I gave the rotor a little push and let the reed switch do the switching. Started at low voltage, slowly turned the knob, and noted every change. The frequency shifted noticeably as speed increased. No transistor, no Hall sensor—just the reed. It’s the same basic circuit I’ve used before but this time I documented the full voltage sweep.

Six magnet rotor

The rotor carries six magnets in a monopolar arrangement. I said on camera that six magnets is superb for this size. It gave smooth running and reached the target RPM without feeling like it was fighting itself. The balance felt good even though it was just resting on the flange instead of floating.

Mayhem clocked six magnet

I called the video pulse motor mayhem because I’ve spent so many days going in circles doing the same wrong things over and over. Today the mayhem paid off. I clocked the six magnet rotor past 1000 RPM and settled at 1033. It felt like a win after all the earlier failures and restarts.

Magnet rotor 1033 just

I kept asking out loud whether I’d have to crank the supply all the way up to break 1000. Turns out I didn’t. At 1009 I was already there, then it eased up to 1033 and 1035. That was the plateau. I decided 1033 was plenty for this rotor size on a simple circuit reed switch. The magnet rotor 1033 just felt like the right place to stop.

Builder checklist

• 666 turns 20-gauge coil, 180° series
• Six magnets, monopolar on rotor
• Simple circuit reed switch
• Variable DC supply (tested 9 V to 20+ V)
• Tac meter for RPM
• Upside-down flange as temporary bearing rest
• Notebook or camera to log voltage, current, and RPM

Troubleshooting

If the rotor hesitates, give it a gentle push and make sure the reed switch is positioned to trigger cleanly. Current jumped from 100 mA to over 3 A at high voltage, so watch your supply. If speed flattens early, you’ve hit the same bell curve I saw around 1000 RPM. Small voltage bumps still changed the sound even when the tac meter moved slowly.

Safety

I mentioned on camera that I don’t consider any of this stuff very safe. The spinning rotor has sharp copper edges and the coil is pulling real current at the top end. Keep fingers clear, don’t leave it unattended at high voltage, and treat the 25 V supply with respect even though it’s low voltage.

FAQ

Why only 1033 RPM?

For this rotor size on a simple circuit reed switch I hit the curve where extra voltage gave less return. I’m cool with 1033.

Did you use maglev?

Not today. The rotor rested on an upside-down flange in the bearing groove.

What current did it draw?

Started around 100 mA at 9 V and climbed past 3 A at the highest voltage I used.

Is this the same as a Bedini?

No, this is a basic pulse motor with a reed switch. I’ve built Bedini-style circuits before but this one is simpler.

Related on this site

• How to Build a Pulse Motor: Parts, Coil Gap, First Spin
• Pulse Motor Rotor Design: Magnets, Materials and Balance
• Pulse Motor vs Bedini Motor: What's the Difference?
• How to Maximize RPM on Your Pulse Motor
• I Finally Got My Pulse Motor Running (Reed Switch)

Watch this experiment on YouTube

• ▶ Watch full on YouTube