I Finally Got My Pulse Motor Running (Reed Switch)

Hook

I finally got the pulse motor to spin with a reed switch instead of the usual trigger coil or Hall sensor. Using coil 32 32 as the main winding, I yanked the transistor, threw in a 200 ohm 100 watt green resistor, and watched the amps settle while the rotor tried to find its groove. It’s messy, hot, and full of alligator clips, but we got motion.

Watch this experiment

We open a fresh pack of high-frequency reed switches rated up to around 1500 RPM. I pulled the extra magnets off the rotor because they were only there for the old trigger coil. With the reed switch in place the air gap got bigger and torque felt low, but the lights blinked and we saw rotation when I stacked the magnets back on.

What you'll learn

You’ll see exactly how I routed power through the reed switch first, why I added the green resistor, what the amp draw looked like on the meter, and why I think a capacitor is the next piece. All straight from the bench with no fancy edits.

From the bench

Summertime in the shop, it’s hot, I’m sweating, and the kids keep popping in yelling happy birthday. Crocodile clips are greasy, connections look weird, and I’m down to whatever parts are on the floor. I shake the reed switches loose, pick one, and start fresh after the first wiring attempt gets too tangled.

How it works / what we changed

Normally the coil is the heart, but this time I put the power into the reed switch first. We removed the transistor altogether to free up connections. The two coils went in series. Power comes in, hits the 200 ohm resistor, then the reed switch, then the coil 32 32. No capacitor yet. I spun the rotor both directions by hand to see if it would catch.

reed switch pulse motor

The reed switch is a simple magnetic switch that closes when the rotor magnets pass. These high-frequency ones should handle the RPM but the magnets I have fly off well before 1500. It definitely recognized the magnets — the light on the power supply blinked and we got some motion, but torque was almost zero at first.

pulse motor reed switch

I hooked the reed switch with the 200 ohm 100 watt resistor right across it. The meter showed 2.7 amps after it leveled, voltage dropped a bit, and the rotor bumped up when I gave it a spin. Pulling the power made it slow down fairly quick. It’s functioning but not strong.

multi pulse motor setup

This is the same multi-coil pulse motor I’ve been tweaking. With the extra magnets removed the air gap grew and the stack of donut magnets on the rotor gave the only visible push. The setup is simple now — just the reed switch, resistor, coils in series, and the power supply at about 6 V.

pulse motor without transistor

We took the transistor out completely. That freed terminals and simplified the circuit but also changed the drive. The reed switch now does all the switching. It works, the lights pulse, but I can feel something is getting in the way of real torque.

200 ohm resistor pulse motor

The green 200 ohm 100 watt resistor is there to limit current so the reed switch doesn’t fry. I mention it might be getting in the way of torque. Amps settled at 2.7–2.9 and the motor did rotate when I stacked the magnets, but it felt weak.

pulse motor capacitor needed

I think we need a capacitor to trap the energy and stack it up so each pulse has enough oomph. Without it the reed switch recognizes the magnets but the torque is low. Next video I’ll pull the resistor, add a capacitor, and try again with the magnets back on stronger.

Builder checklist

• High-frequency reed switch (up to ~1500 RPM rating)
• Coil 32 32 or your chosen trigger winding
• 200 ohm 100 W resistor (or experiment without)
• Alligator clips or fresh solder joints
• Stack of neodymium or donut magnets on rotor
• Capacitor on the todo list for next build
• Multimeter or power supply with amp readout

Troubleshooting

If you get recognition but no torque, check the air gap — mine grew after removing extra magnets. Amps high and zero spin? Resistor value might be too high. Lights blink but rotor barely moves? Try a capacitor to store pulse energy. Sweaty hands making clips slip? Keep a rag handy and take breaks.

Safety

These reed switches can handle decent current with the resistor but don’t skip it on your first try. Power supply was around 6 V and we saw nearly 3 A — keep an eye on heat in the resistor. Magnets can snap together fast; watch your fingers. Work in a ventilated spot, especially when it’s already hot.

FAQ

Do I still need the trigger coil with a reed switch?

In this test I used coil 32 32 but the reed switch replaced the usual sensing. You can run without a separate trigger coil.

Why add the 200 ohm resistor?

To protect the reed contacts from too much current. I wonder if it’s killing torque though.

Will it run without a capacitor?

It spins a little but feels weak. I conclude we probably need one to stack energy between pulses.

Can I use different gauge wire?

We stuck with coil 32 32 this time. The transcript mentions debating 26 gauge too but stayed small.

Related on this site

• How to Build a Pulse Motor: Parts, Coil Gap, First Spin
• Pulse Motor vs Bedini Motor: What's the Difference?
• Using a Hall Effect Sensor in Your Pulse Motor Build
• Best Wire Gauge for Pulse Motor Coils (AWG Guide)
• I Finally Got My Pulse Motor Running (Reed Switch)

Watch this experiment on YouTube

• ▶ Watch full on YouTube