Hello, An electronic newbie here
Recently I tried to make an electromagnet with stuffs I had currently, below are the question i faced.
They are Fundamental questions ：
Will it short circuit when positive terminal is arduino 5V, negative terminal is GND ?
(I saw online many people just connect to battery at both ends)
2.Does the material need to be electric conductor ?
(I saw online they only use nails without giving reason)
Does the insulating layer of copper wire need to be removed? What are the suggested wire diameter
(I saw online some people removed whereas some people doesn't)
Please provide answers in [ Question No, Yes/No, Why ] format
The schematic I tried to draw is attached below
I know there is miniature solenoid electromagnet selling at cheap price,
but i just want to try with existing resources before buying new
Googling design of an electromagnet would be my first port of call.
you dont strip the insulation off
if you want to pick things up at the ends , you need a magnetic material up the centre of your coil.
the wire diameter you use and the number of turns dictates the power of the magnet and the current it takes . It’s a pretty complex problem to solve , but worth experimenting on .
I’d suggest you also read up on some basic electrics - ohms law, voltage and current
Sorry this is the schematic i tried to draw, not sure does it statisfy the format
[edit]
Q1. Will it short circuit when positive terminal is arduino 5V, negative terminal is GND ?
Q2.Does the material need to be electric conductor ?
Q3. Does the insulating layer of copper wire need to be removed? What are the suggested wire diameter
The wire needs to be very long, very thin enamel copper wire. The core of the magnet needs to be soft iron, a large nail or bolt is good for this kind of experimentation.
The insulating layer needs to be removed at the ends to make the connection. Only at the ends, leave the rest on otherwise it will short out.
You can't power from an Arduino, an Arduino is a microcontroller, not a power supply. Use some AA batteries for experimenting.
To strip the insulation from the ends try burning it with a match or candle flame.
UKHeliBob:
1 - not sure what you mean by short circuit. The amount of current that flows will depend on the resistance of the coil
2 - yes
3 - no. If you remove the insulation you won't have a coil, will you
Hi UKHeliBob, First, Thanks For The Reply !
For
Q1. I ask about short circuit because I saw people saying Arduino UNO Board will short circuit (like burning or exploding) when the 5V DC output is connected to the GND directly. In the solenoid, Negative and Positive terminal are connected to the GND and 5V source of Arduino Uno directly, so i wonder will the UNO board still be short circuiting
Q2. Ok understood
Q3. Does that means it could not be an electromagnet if i use pure copper wire rolls without insulator as a coil ? since the copper wire roll does not have insulating plastic outside of it
The wire needs to be very long, very thin enamel copper wire. The core of the magnet needs to be soft iron, a large nail or bolt is good for this kind of experimentation.
The insulating layer needs to be removed at the ends to make the connection. Only at the ends, leave the rest on otherwise it will short out.
You can't power from an Arduino, an Arduino is a microcontroller, not a power supply. Use some AA batteries for experimenting.
To strip the insulation from the ends try burning it with a match or candle flame.
Hi Perry, Thanks for the reply !
For
Q3. Does that means i cannot use an uninsulated copper wire roll to make an electromagnet? By the way, if the insulating plastic is desired, can I make one electromagnet with jumper wires ? They have insulating layer afterall
(I'm not sure the copper wire roll has insulated layer or not as they appears to be in copper colour)
The wire must be insulated, otherwise you have a big short circuit.
There are 2 problems with using plastic insulated wire:
Plastic melts. Lots or turns of wire on top of each other will get hot from the current and melt plastic insulation. Enamelled wire will withstand higher temperatures.
Plastic insulation is relatively thick, which means the conductors end up spaced out, which means the magnetic field is weaker then it otherwise would be if the conductors were closer.
Enamel copper wire is sort of copper colour. Scrape or burn the ends to see if anything comes off. If nothing comes off then there is nothing there and it's not insulated.
The wire used for the coil must be insulated and if you are going to power it from the Arduino GND and 5V pins its resistance must be such that it does not pass more current than an Arduino pin can supply. Even if that is the case then it is still not a good idea because the Arduino is not intended to be used as a power supply. In any case, suppose that the resistance of the wire constrained the current to say 10mA, then the magnetic force provided by the coil would be miniscule
If you really want to do this then the current flowing through the coil needs to come from an external power source and be switched by a relay, transistor or MOSFET controlled by an Arduino pin
Short circuit becomes ambiguous here. Connecting positive and negative together is indeed called a short. You want to put an electromagnet in between - now it's not a short, there's an electromagnet in the current path. However depending on the construction an electromagnet may draw a lot of current, for an Arduino that's effectively a short: the current demanded is far more than it can deliver (the 5V pin can deliver ~500 mA when the board is powered by 5V USB). A set of AA alkaline batteries can deliver some 10A (for a short period of time). That is enough for thin wires to start smoking and the batteries themselves to heat up, symptoms of what we typically call a short circuit.
For your eletromagnet, get a long piece of thin enamel wire (can be harvested from transformers, if you can't find it in the shops). Measure the resistance between the ends with your multimeter, that combined with your supply voltage will tell you the current you can expect to run through it when you use that wire to wind the magnet. Make sure that this current is well within the ability of your power supply, otherwise you have that dreaded short again.
You need to scrape the insulation off the end of the wire in order to make an electrical connection.
If you scrape the end with sand paper and your wire changes colour then you have insulated wire and you can make a coil. Many insulating layers are copper coloured.
You must not connect the coil to an Arduino pin, nor the Arduino’s 5V supply because unless the coil has many hundreds of turns it will draw too much current. You should use a rely to control turning the coil on and off.
2.Does the material need to be electric conductor ?
Yes but not any conductor. For example copper is a conductor but it is not magnetic. So to attract something by magnetism it has to contain some ferrous metal, there are three sorts, iron, nickel or cobalt.
Hello Guys Thanks For The Replying !
I think Enamel Copper Wire is the one I'm searching.
I always thought the Copper Wires doesn't have insulation as they are copper colour ( but i'm wrong )
UKHeliBob, I just planning to make the electromagnet at the beginning with jumper wires i currently have, before buying new electric components like the minature electromagnets. The electromagnet will used to put infront of a crane, or trying to float something up in the air.
A decent electromagnet easily takes a couple hundred turns; I'd be looking for a quantity of wire that has a resistance of at least 20Ω, so the current at 5V is no more than 250 mA (that's still 1.25W of heat dissipation, so if the magnet is used long term you have to offer a place for that heat to go).
That means you have to have a paramagnetic material, that is one that is repelled by a magnetic field, not attracted to it. Paramagnetism - Wikipedia
I would suggest that given the level of technical knowledge you have displayed in the questions you have asked then forget that until you have a lot more experience.
Grumpy_Mike:
I would suggest that given the level of technical knowledge you have displayed in the questions you have asked then forget that until you have a lot more experience.
Sage advice in this case!
Grumpy_Mike:
You must not connect the coil to an Arduino pin, nor the Arduino’s 5V supply because unless the coil has many hundreds of turns it will draw too much current.
Thousands of turns.
Just winding a useful electromagnet requires special equipment, you cannot do this by hand.
Not even worth attempting. If you seriously want to do this experimentation, you need to buy (or scavenge, though I cannot at present think of a source) the electromagnet for which you have adequately researched its operating characteristics - resistance, operating voltage and duty cycle.
