Uploaded December 2024 | Updated September 2026, 2 weeks ago

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We are running experiments to see why the bobbin windings in a capacitively tuned crystal radio did not work. There was almost no sound.

We are starting with a known, working coil and 1 by 1 varying the parameters that were changed with the bobbin coils:
-- Wire diameter, straight wind (this video)
-- Core size
-- Winding type (straight 1 layer vs. multi-layer scatter)

KNOWN COIL:
- Wire size big: 0.81mm (20 AWG)(Done/standard) Straight wound
- Core: 42 mm (1.65") PVC plastic
- Inductance total: 205 uH
- Taps: 0T, 20T, 30T, 80T


EXPERIMENTAL COIL:
- Wire size fine: 0.227mm (31 AWG)(Done/standard) Straight wound
- Core: 42 mm (1.65") PVC plastic
- Inductance total: 220 uH
- Taps: 0T, 10T, 15T, 40T


BOBBIN COIL (capacitively tuned version):
- Wire size fine: 0.227mm (31 AWG)(Done/standard) Multi-Layer Scatter Wound
- Core: 8 mm (1.65") plastic
- Inductance total: 219 uH
- Taps: 0T, 10T, 15T, 40T

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RELATED VIDEOS:
Crystal Radio--The Bobbin Inductors Fail. But WHY? 2/2
youtu.be/iH66WckUzFE

Crystal Radio--No More Small Core Inductors??? Maybe. 1/2
youtu.be/CJlAwvE5p7g

Crystal Radio--Cheap & Easy Inductor From Sewing Machine Bobbin
youtu.be/ecuhAiBYJzs

1 Capacitor Crystal Radio--No More Variable Capacitor Designs? (4K)
youtu.be/0AvTO588SyU