Coilers Club #2 Electromagnet Coiling Tools
Designing an Electromagnet.
From a practical standpoint.
Lets say I want 1000 Ampere turns. Thats about what it takes to lift N grams of Iron vertically from the ground . for this I can have 1 wire carrying 1000A or I can do it otherwise, Have 1A, coiled in 1000 turns. Same differance. 1000AT .
I have a 24V DC supply that maxes on 3A . Thats my design limit. The voltage and ampere is adjustable dialers, and both units have BCD displays.
U = Volt
I = Ampere
R = Ohm
What I first do is this .
Turns = AT / I = 1000AT / 3A = 333 turns
A wire I have handy is AWG24, Ø = 0.511 mm diameter CU . For a test coil 3 Amperes in this crossection is in range . I measure the real wire with a Micrometer and with insulation it reads about 0.6 mm Ø .
I then "Block" the coil, meaning the turns have equal turns in lenght as in height, multilayered . So it forms a ring, with a square block "toroid shape" . The diameter of the donut hole, or Coil Diameter determines the resistance of the entire coil. Large diameter , much resistance per turn . The coil function or use, allows desirable values, or design limits with the stocks material at hand. Iron is not considered here, nor is it used in this example. A coil Block form, is done by Square Root of total number of Turns.
SQRT 333 turns = 18.24 Turns * Layers . 18 * 18 = 324
Then , multiplying in wire mm to get the real size
18.2 turns * 0.6 mm = 10.94 mm long coil.
Coil Inner Diameter, donut hole.
ID = 30mm
OD = 30 mm + 10.9 = 40.94 mm outer diameter of the coil.
Circumference of turns
IC = pi * 30 = 94.2 mm
OC = pi * 40.94 = 128.61 mm
Average of turns = IC + OC / 2 = (94.2 + 128) / 2 = 222/2 = 111.4 mm average
Convert to Meter = 111 / 1000 = 0.11 meter . 11 centimeter .
Convert to inches = 11 cm / 2.54 inch = 4.3 inch
Lenght of wire = 1 turn average * N turns total = 0.11 meter * 333 turns = 37.1041553 meter total lenght of wire .
Ohm per meter = 0.0841 ohm/m
Coil total Ohm = 0.0841 * 37 m = 3.12 ohm
Find voltage to drive the coil .
U = I * R ohm = 3A * 3.12 ohm = 9.36 volt is required to obtain 3A on that coil.
Really ?
Trust no human.
Trust in nature, and its ways.
In there is knowledge, that surpass, convention .
Dudes & Dudettes
Ladies & Gentelmen
We share the world , in our time. we look at eachother. we obsere eachorther, think of eachother. we live in the same time. in the same world. of all combinations that might be possible. this is the one we share. This is the world we describe. this is the world we have in common .
Cheers
Kenneth H. Olsen
22.02.2019
I can lift 110 grams of Iron, with 1000AT, ampere turns .
It appears the strongest grip from the magnetic field is just inside the coil donut hole.
Temprature of the coil is about 70 Celcius. The Voltage drop, due to increased Resistance on the wire because of heat (IR), makes the Ampere go lower 2.7A , 2.5A. Ohm is a variable, when Ampere is applied to the circuit . The temprature is more or less stabile at 75C , after 5-10 minutes of drift . the effect is reduced with Voltage drop, and the deviation is stabilised when the Temprature settles .The max tolerance for the wire insulation is 150C . then it starts to fume .
23.02.2019
A neat method for having all the turns on the coil in an orderly fashion . Usually the turns start to fringe up the orderly pattern near the flanges, in the corners. when the pattern is disrupted. I add one turn of paper, Office copy machine paper is ok. one round of this over the coil. then start the orderly coiling again . this will make the coil outer circumference look all smooth. and the paper gives the coil a breather .
From a practical standpoint.
Lets say I want 1000 Ampere turns. Thats about what it takes to lift N grams of Iron vertically from the ground . for this I can have 1 wire carrying 1000A or I can do it otherwise, Have 1A, coiled in 1000 turns. Same differance. 1000AT .
I have a 24V DC supply that maxes on 3A . Thats my design limit. The voltage and ampere is adjustable dialers, and both units have BCD displays.
U = Volt
I = Ampere
R = Ohm
What I first do is this .
Turns = AT / I = 1000AT / 3A = 333 turns
A wire I have handy is AWG24, Ø = 0.511 mm diameter CU . For a test coil 3 Amperes in this crossection is in range . I measure the real wire with a Micrometer and with insulation it reads about 0.6 mm Ø .
I then "Block" the coil, meaning the turns have equal turns in lenght as in height, multilayered . So it forms a ring, with a square block "toroid shape" . The diameter of the donut hole, or Coil Diameter determines the resistance of the entire coil. Large diameter , much resistance per turn . The coil function or use, allows desirable values, or design limits with the stocks material at hand. Iron is not considered here, nor is it used in this example. A coil Block form, is done by Square Root of total number of Turns.
SQRT 333 turns = 18.24 Turns * Layers . 18 * 18 = 324
Then , multiplying in wire mm to get the real size
18.2 turns * 0.6 mm = 10.94 mm long coil.
Coil Inner Diameter, donut hole.
ID = 30mm
OD = 30 mm + 10.9 = 40.94 mm outer diameter of the coil.
Circumference of turns
IC = pi * 30 = 94.2 mm
OC = pi * 40.94 = 128.61 mm
Average of turns = IC + OC / 2 = (94.2 + 128) / 2 = 222/2 = 111.4 mm average
Convert to Meter = 111 / 1000 = 0.11 meter . 11 centimeter .
Convert to inches = 11 cm / 2.54 inch = 4.3 inch
Lenght of wire = 1 turn average * N turns total = 0.11 meter * 333 turns = 37.1041553 meter total lenght of wire .
Ohm per meter = 0.0841 ohm/m
Coil total Ohm = 0.0841 * 37 m = 3.12 ohm
Find voltage to drive the coil .
U = I * R ohm = 3A * 3.12 ohm = 9.36 volt is required to obtain 3A on that coil.
Really ?
Trust no human.
Trust in nature, and its ways.
In there is knowledge, that surpass, convention .
Dudes & Dudettes
Ladies & Gentelmen
We share the world , in our time. we look at eachother. we obsere eachorther, think of eachother. we live in the same time. in the same world. of all combinations that might be possible. this is the one we share. This is the world we describe. this is the world we have in common .
Cheers
Kenneth H. Olsen
22.02.2019
I can lift 110 grams of Iron, with 1000AT, ampere turns .
It appears the strongest grip from the magnetic field is just inside the coil donut hole.
Temprature of the coil is about 70 Celcius. The Voltage drop, due to increased Resistance on the wire because of heat (IR), makes the Ampere go lower 2.7A , 2.5A. Ohm is a variable, when Ampere is applied to the circuit . The temprature is more or less stabile at 75C , after 5-10 minutes of drift . the effect is reduced with Voltage drop, and the deviation is stabilised when the Temprature settles .The max tolerance for the wire insulation is 150C . then it starts to fume .
23.02.2019
A neat method for having all the turns on the coil in an orderly fashion . Usually the turns start to fringe up the orderly pattern near the flanges, in the corners. when the pattern is disrupted. I add one turn of paper, Office copy machine paper is ok. one round of this over the coil. then start the orderly coiling again . this will make the coil outer circumference look all smooth. and the paper gives the coil a breather .
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