# How to change wire turns for electromagnet field strength?

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#### russwr

Joined Aug 29, 2017
30
How to increase number of turns for same value magnetic field strength 12 volt electromagnet of original 10amps DC + 7 turns and 13 turns, being changed to 6 amps DC worth of SAME magnetic field? (Simple proportions always come out for less turns.) It uses copper core of 7 turns connected to 13 turns 4mm rod steel core all on 10 amps. There is an electronics formula method that uses different constants for air, copper, steel, iron , and ferrite cores, that may not be needed. My guess calculation may be wrong. (I was thinking on 12 turns and 24 turns)

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#### MisterBill2

Joined Jan 23, 2018
16,569
It is not even clear just what the question actually is. Just what sort of electromagnet is desired, and just what sort of core is actually in use? Aside from that, the current depends on the wire size as well as the number of turns. And " It uses copper core of 7 turns " is rather confusing because copper is not likely to be magnetic.
So a great deal more explanation would clarify what advice is needed. Stating only the perceived problem and asking for the answer is seldom the best way to obtain a useful answer.

#### russwr

Joined Aug 29, 2017
30
What is the appropriate ratio math proportion to use to determine increase number of insulated wire turns for 10amps through 13 turns #12 gauge wire over steel rod for sample electromagnet, X magnetic field strength, and then changed to 6 amps current with same X magnetic field strength?

#### BobTPH

Joined Jun 5, 2013
8,104
The field is proportional to turns times current. So if you reduce the current to a factor of 0.6, you need to increase the turns by a factor if 1/0.6 = 1.67. So you would need 17 turns to create the same field.

#### russwr

Joined Aug 29, 2017
30
So.........., the new updated electromagnet would now have 12 turns over copper core, and 22 turns over steel core, for the same magnetic field by reducing the current by .6 factor. 10A to 6 amp. 10A / 6A = 1.67 factor. Multiply original turns of 7t + 13t in series ,each by 1.67. OK, I got it now. This is assuming the scope value of DC current reading over a one ohm resistor, for Ohm's law, is the same as on hand held cheap DC panel current meter. E volts scope probe read over ground side of - in series 1 ohm resistor, read accross resistor, is same as the current value. E / 1 ohm = 6amps.
Would it be better to use extra wound turns on electromagnet, and then use manual slidable steel rod core , so as to vary the inductance so as the magnetic field is adjusted by the current meter desired setting, with in series resistor? The radio circuits use a plastic diddle stick to adjust the tiny IF transformers, as they have a outer threaded ferrite core that screws in + out of the wire coil.

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#### ericgibbs

Joined Jan 29, 2010
18,232
Hi Al,
They work OK for me,
A clip.
E

#### MrAl

Joined Jun 17, 2014
10,906
Hi Al,
They work OK for me,
A clip.
E
View attachment 303748
Hi Eric,

Yeah very strange, I just tried the first one again and it worked fine. Must have been a temporary problem with the site.

#### MisterBill2

Joined Jan 23, 2018
16,569
What I find confusing here is why there are any turns of wire wrapped around a COPPER core. Copper, in a changing magnetic field, works like a short-circuited turn, with current flowing but usually not doing anything useful, except where it is creating a shaded pole in some very specific applications.

#### russwr

Joined Aug 29, 2017
30
What I find confusing here is why there are any turns of wire wrapped around a COPPER core. Copper, in a changing magnetic field, works like a short-circuited turn, with current flowing but usually not doing anything useful, except where it is creating a shaded pole in some very specific applications.

#### russwr

Joined Aug 29, 2017
30
Discussions related to overunity systems are forbidden on this site.
The 1st section of the S1R9A9M9 triple coils assembly had a 90 degree windings of insulated #14 gauge over the copper 5 turn coil. This was to help restrict back flow of current without using diode. Also, the technique had put a magnetic field from the #14 gauge wiring over the copper core + steel core to cause an extension of on time of the flow circuit. This was back in 2008 of garage work in Georgia experimentation shown to public. The series 1st and 2nd section assembly needed to be changed from 10 amps worth of magnetic field overall to 6 amps , with same field intensity for proper SAME retiming of 1 cylinder engine,......past TDC to ATDC about -34 degrees. 10 amp current flow not necessary. The special- specific windings technique also did several other things at the same time. - Such as leakage inductance cross voltage transfer of one source superimposed on second source. The one source didn't have enough voltage to push 10amps through 125ohm load.

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#### shortbus

Joined Sep 30, 2009
10,038
What I find confusing here is why there are any turns of wire wrapped around a COPPER core. Copper, in a changing magnetic field, works like a short-circuited turn, with current flowing but usually not doing anything useful, except where it is creating a shaded pole in some very specific applications.
You just don't understand over unity. When you see someone referring to "S1R9A9M9", they are talking about over unity experiments. He has had at least one thread so far locked for over unity

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