Pancake Bifilar Coil Build for Pulse Motor Generator

Papa Bale builds his first pancake bifilar coil on the bench while working on pulse motor electricity generation. The coil uses 26 gauge strands in series plus a single 28 gauge strand, held together with electrical tape. He tests it live, deals with a sticking switch and iron filing core, then decides to hook up the hall effect again.

Key takeaways

• First pancake bifilar coil attempt is held together with electrical tape and isn't perfectly uniform
• Wiring uses one 28 gauge strand alone plus 26 gauge strands configured as one single, two in series, then three in series
• Switch gets hot and sticks, causing amps to rise and the motor to poop out before it really gets going
• Iron filing core in the coil is likely causing extra drag and higher amp draw
• Testing resistors up to 22 ohms but all are only 0.5 watt rated
• Plans to switch back to hall effect sensor to replace the problematic mechanical switch

In this bench session I'm juggling two projects at once: generating electricity with the pulse motor and finishing my very first pancake bifilar coil. The coil isn't uniform because I don't have a great workspace, but it's solid enough for testing. I used only electrical tape to hold everything—no fancy winding jig this time.

The spool had about 100 feet of wire. I wasn't sure if I needed a full 100 foot pancake coil though, so I asked viewers what length they recommend—I'm guessing 50 feet might be plenty. Live on camera the lights came on right away when I fired it up. The wiring is one 28 gauge strand by itself, then the 26 gauge strands go one single file, two in series, then three in series for all six strands.

We saw the switch get hot fast. When the switch sticks the amps climb and the whole thing bogs down. There's a lot of iron filing core in the coil which is probably slowing the rotor and pulling more current. I was testing different resistors and landed on 22 ohms but they're all half-watt parts so they're getting stressed. The blinking LED was neat but the motor poops out right when it should accelerate. That's why I'm going back to the hall effect again to replace the mechanical switch.

Overall it's messy DIY but the coil lit the light and proved the concept even if the switch is the weak link.

Related on this site

• How to Wind Coils for a Pulse Motor (Step by Step) — Directly supports the pancake bifilar coil winding discussion and first-build lessons
• Using a Hall Effect Sensor in Your Pulse Motor Build — Matches the decision to hook the hall effect again after switch problems
• Best Wire Gauge for Pulse Motor Coils (AWG Guide) — Compares the 26 gauge and 28 gauge strands used in the bifilar layout
• I Finally Got My Pulse Motor Running (Reed Switch) — Related earlier pulse motor trigger success that contrasts with the current switch trouble

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