Two Bedini Circuits Running a 9-Mag Rotor and 4-Mag Rotor at 600 RPMs

Hook

I ran two Bedini circuits on the same pulse motor and watched a 9 magnet rotor and a 4 magnet rotor Celtic cross both climb to around 600 RPM. Then I tried combining their collector dumps into one coil and things got interesting.

Watch this experiment

I set up the bench with two separate Bedini circuits. One circuit connects to a coil facing the 9 magnet rotor, the other to a coil on the 4 magnet rotor. Both rotors spin up and I grab tach readings on each.

What you'll learn

You’ll see real bench measurements on two different rotor designs running from two Bedini circuits, what happens when you merge the collector spikes, and why each circuit seems happier with its own load coil.

From the bench

I started with the 9 magnet rotor side first. The first Bedini circuit fires its coil and the rotor gets up to 603 RPM on the tach. Then I fire the second circuit on the 4 magnet rotor and it settles at 579 RPM. Pretty close for two completely different magnet counts.

Both circuits are dumping their spikes somewhere, and I wanted to test whether feeding both collector outputs through diodes into just one of the motor coils would make that side run better or at least the same. So I rewired on the fly.

How it works / what we changed

With both collector dumps now going into a single coil we get twice the spike coming in. I put the tach back on and the reading drops about 100 RPM. It clearly ran worse. So I switched it straight back to the original separate-coil setup.

Once everything is running normally again the second motor really wakes up. It climbs from around 523 RPM quickly up to 546 and keeps going. The two circuits appear to help each other when each has its own coil to work with. The end of one circuit and the start of the other seem to interact in a useful way.

bedini circuits one

I used two separate Bedini circuits, each built the classic SSG style. One Bedini circuit runs the coil for the 9 magnet rotor while the second Bedini circuit runs the coil for the 4 magnet rotor. Each has its own trigger and its own path for the collector dump. When I tried routing both collector outputs into a single coil the performance dropped, so I put them back to independent operation.

magnet rotor celtic

The second rotor is a 4 magnet rotor built in a Celtic style. It uses four magnets arranged in a cross pattern that gives it a distinct magnetic signature compared with the 9 magnet rotor. Even with only four magnets it still reached 579 RPM when driven by its own Bedini circuit on the shared motor shaft, nearly matching the 9 magnet side.

rotor celtic cross

I call the 4 magnet rotor the Celtic cross because the magnets sit at the cardinal points like a cross. It spins on the same shaft as the 9 magnet rotor but uses its own dedicated coil and Bedini circuit. Once both circuits are running the Celtic cross rotor helps bring the second motor up to speed quickly, hitting over 540 RPM and showing that even a simple four-pole layout can keep pace with a higher pole count rotor in this setup.

Builder checklist

• Two separate Bedini/SSG circuits, each with its own trigger coil and power transistor
• One 9 magnet rotor and one 4 magnet Celtic cross rotor on a common shaft
• Two drive coils, one aimed at each rotor
• Tachometer for real-time RPM checks on each side
• Diodes ready if you want to test combining collector dumps
• Extra load or second motor to give each circuit something to dump into

Troubleshooting

If your RPM drops after combining the collector spikes, go back to separate coils for each circuit. I lost about 100 RPM when I doubled up on one coil. Also make sure both circuits are getting a clean trigger signal from their respective rotors. The interaction between the two motors only really kicks in once both sides are already spinning.

Safety

These circuits can produce sharp voltage spikes. Keep your hands clear of the spinning rotors and use proper diodes on the collector paths. Work on a non-conductive surface and keep batteries or power supplies isolated when experimenting with dump paths.

FAQ

Can two Bedini circuits share one coil?

In my test it actually ran worse. Separate coils gave higher and more stable RPM.

Why did the 9 magnet and 4 magnet rotors reach similar speeds?

Weird but true on this bench. Both settled right around 600 RPM once the circuits helped each other out.

Do the circuits interact with each other?

Yes. Once both are running the second motor speeds up noticeably and they seem to support one another.

Related on this site

• How to Build a Pulse Motor: Parts, Coil Gap, First Spin
• Bedini Motor & SSG Circuit Guide (Beginner Bedini Explained)
• Pulse Motor Rotor Design: Magnets, Materials and Balance
• Pulse Motor vs Bedini Motor: What's the Difference?

Watch this experiment on YouTube

• ▶ Watch full on YouTube