Crystal Radio Coil, Fine-Wire Small Core Experiment 3/3

Описание: We are running experiments to see why the bobbin windings in a capacitively tuned crystal radio did not work. There was almost no sound. This round we are checking the effects of smaller diameter coil cores.


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 (video #1)
-- Core size
-- Winding type (straight 1 layer vs. multi-layer scatter)


KNOWN STANDARD 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:
https://coil32.net/online-calculators...
Wire size fine: 0.227mm (31 AWG)(Done/standard) Straight wound
Core: 8 mm (x") PLA plastic
Inductance total: 205 uH Target (207 measured)


ENTER THE INPUT DATA:
L = 205 uH – Required inductance
D = 8 mm – Diameter of coil-former circumference = 25.13 mm
d = 0.227 mm – Diameter of wire without insulation 31 AWG
k = 0.24717 – Diameter of wire with insulation
RESULT:
N = 780.822 – number of turns
l = 192.997mm – Length of winding


Length of wire = 25.13mm x 780.822T = 19,622.05686mm or 19.6 meters
20T / 130T = 0.1538461538461538 (x 780.822T = 120.1265T) (x 19.6 m = 3.01539 m)
30T / 130T = 0.2307692307692308 (x 780.822T = 180.19T) (x 19.6 m = 4.5231 m)
80T / 130T = 0.6153846153846154 (x 780.822T = 480.5058T) (x 19.6 m = 12.0615 m)



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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