06-04-2019, 10:05 PM
Hi Z,
My calcs below were for the later C35M dynamo but may help you in having a go rewinding. I used varnished copper wire available from the Bay of E under 'copper magnet wire' with tape from the same suppliers and a home made winding jig. If I were to remake the jig I'd make the sides stronger, the pressure from keeping the wire tight tended to bulge out the thin ply. Keeping the wire tight, laying it down evenly while keeping a good score of the number of turns as you're winding is a bit of a challenge!
Dave
Standard Lucas C35M 6v field
90 coils, 0.88mm diameter, 20 gauge wire per pole. Approx 310mm per turn = 27.9m per pole.
From look up table 20g wire has resistance of 26.3 Ohms per kilometre = 0.0263 Ohms per metre. One pole should therefore be approx 0.733 Ohms
Amp turns (an expression of the magnetic field generated);
F = NI
At 6v; V= IR; 6 = I x 1.4, Field current is approximately 4A
F = 90 x 4
F = 360
If used with 12v; 12 = I x 1.4, Field current is approximately 8.5A
F = 765
12v fields
21g resistance of 33.2 Ohms per kilometre = 0.0332 Ohms per metre.
Density = 0.00463Kg/m, At 0.31m per turn, there’s approximately 350 turns on a 21g 0.5Kg drum.
If get +50%, 135 turns, in the space;
Resistance = 1.39 Ohms, field resistance of 2.78 Ohms
Wire length = 41.85m = 0.19Kg per pole, 0.39Kg per field
F = 582
If get +75%, 155 turns, in the space;
Resistance = 1.62 Ohms, field resistance of 3.24 Ohms
Wire length = 48.83m = 0.23Kg per pole, 0.45Kg per field (two from a .5Kg reel)
F = 574
If get +100%, 180 turns, in the space;
Resistance = 1.85 Ohms, field resistance of 3.7 Ohms
Wire length = 55.8m = 0.2Kg per pole, 0.4Kg per field
F = 583
Go for 160 turns 21g, 0.75mm, 0.81mm over varnish
Design
Resistance of 33.2 Ohms per kilometre = 0.0332 Ohms per metre.
Density = 0.00463Kg/m
160 turns of .31m gives wire length = 49.6m, 0.17Kg per pole, 0.34Kg per field
Resistance = 1.65 Ohms per pole, field resistance of 3.3 Ohms
F= 582
Actual built
Weight wound into 160 turns = 0.22Kg of wire
62.15m, giving 2.06 Ohms for pole, field resistance 4.1 Ohms
Field current 2.9 Amps
F = 468
My calcs below were for the later C35M dynamo but may help you in having a go rewinding. I used varnished copper wire available from the Bay of E under 'copper magnet wire' with tape from the same suppliers and a home made winding jig. If I were to remake the jig I'd make the sides stronger, the pressure from keeping the wire tight tended to bulge out the thin ply. Keeping the wire tight, laying it down evenly while keeping a good score of the number of turns as you're winding is a bit of a challenge!
Dave
Standard Lucas C35M 6v field
90 coils, 0.88mm diameter, 20 gauge wire per pole. Approx 310mm per turn = 27.9m per pole.
From look up table 20g wire has resistance of 26.3 Ohms per kilometre = 0.0263 Ohms per metre. One pole should therefore be approx 0.733 Ohms
Amp turns (an expression of the magnetic field generated);
F = NI
At 6v; V= IR; 6 = I x 1.4, Field current is approximately 4A
F = 90 x 4
F = 360
If used with 12v; 12 = I x 1.4, Field current is approximately 8.5A
F = 765
12v fields
21g resistance of 33.2 Ohms per kilometre = 0.0332 Ohms per metre.
Density = 0.00463Kg/m, At 0.31m per turn, there’s approximately 350 turns on a 21g 0.5Kg drum.
If get +50%, 135 turns, in the space;
Resistance = 1.39 Ohms, field resistance of 2.78 Ohms
Wire length = 41.85m = 0.19Kg per pole, 0.39Kg per field
F = 582
If get +75%, 155 turns, in the space;
Resistance = 1.62 Ohms, field resistance of 3.24 Ohms
Wire length = 48.83m = 0.23Kg per pole, 0.45Kg per field (two from a .5Kg reel)
F = 574
If get +100%, 180 turns, in the space;
Resistance = 1.85 Ohms, field resistance of 3.7 Ohms
Wire length = 55.8m = 0.2Kg per pole, 0.4Kg per field
F = 583
Go for 160 turns 21g, 0.75mm, 0.81mm over varnish
Design
Resistance of 33.2 Ohms per kilometre = 0.0332 Ohms per metre.
Density = 0.00463Kg/m
160 turns of .31m gives wire length = 49.6m, 0.17Kg per pole, 0.34Kg per field
Resistance = 1.65 Ohms per pole, field resistance of 3.3 Ohms
F= 582
Actual built
Weight wound into 160 turns = 0.22Kg of wire
62.15m, giving 2.06 Ohms for pole, field resistance 4.1 Ohms
Field current 2.9 Amps
F = 468