# Tagged Questions

The Element Cu known for its electrical and thermal conductivity, both of which are exploited in EE. THis material is typically what is used in PCB's for the traces and also modern CMOS processes have Cu layers in them due to it's superior conductivity. You also see copper in heat sinks to carry ...

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### How to calculate the resistance measured between probes in water

I have read already quiet a lot about the conductivity of water/ fluids but i can not find a formula to calculate the resistance between probes in a fluid. For example: use-water-as-a-conductor-for-a-...
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### Does oxidized copper conduct electricity?

When the surface of copper turns that greenish oxidized color, does the resistance to current flow increase or isn't affected? For instance if the point of contact is secure and clean but bare ...
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### 9V battery positive soldering pad went off from my circuit board

OK, so I got a little problem. Today I was soldering something on this circuit board and the positive wire tore apart. I had to resolder the wire, but when I was heating up the old solder to remove it,...
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### Measuring the temperature of copper wire

I'm doing an experiment with copper wire, and I need to be able to measure the temperature of the wire. I've looked into temperature sensors and infrared thermometers, but I'm not sure how to ...
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It says that the energy of the EM wave decays rapidly if it travels through a good conductive material. Therefore, much of the wave is travelling on the surface of the copper wire. (since it decays ...
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### How to remove Kapton polyimide film from Pyralux cupper sheet?

I want to etch Pyralux sheet and will follow this tutorial. The sheet I want to try is LF9120R and it is 1 oz of copper per square ft (or 305g/m^2). They describe ...
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### There is thermochromic pigment. Is there a magnetic variety of pigment?

I can mix thermochromic pigment with transparent epoxy resin into a brightly colored paste which changes colors when it detects a temperature threshold in the surface it is applied to. Is it ...
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### Burning Temperature of Copper Winding of Motor

Burning Temperature of Copper Winding of Motor. I Have 3 motors 150watt 0.75Amp 220V in Copper and Aluminum and Copper clad aluminum. I want to know the maximum internal temperature of these motors ...
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### Apply etch resist on copper

I cannot get my toner etch resist on to my copper board. I'm doing with the iron, but each time I try the ink does not transfer completely. I've tried many things - applying some water on it, ...
117 views

### How do wires connect to transistors?

So I was looking at the schematic of NPN and PNP transistors which basically involved layered blocks of doped material stacked. My question is how do wires connect to these devices? I think this ...
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### Phone charger basic question

I'm (kinda) new to electronics and I have a simple question... So, I have a phone charger and I cut the wire because I wanted to connect the PWR and the GRD to another circuit. But when I connected ...
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### Welding Thermocouple to Test Sample

I have a 3mm copper test sample that is going to get heated up, and I would like to know how hot it is actually getting. Previously, we have just held the thermocouple close to the sample, but we are ...
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### Materials for a speaker [closed]

if I have a flat, copper sheet and a magnet, Can I make a speaker? Or do I need magnet wire coiled up?
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### Heat Kathal with D Cell batteries

I have Kanthal A1 26AWG (3.21 Ohms). I need to heat a small cardboard box (Tissues box) 15 degrees Celsius over the room temperature. And I am using 2 D Cell Batteries of 1.5V. I coil the Kanthal ...
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### Add exposed copper to eagle board?

I am new to using eagle. I want to put some exposed copper pads that I can solder to on my board. The catch is that they cannot have through holes. I tried just making polygons in the top layer, but I ...
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I'm building oscillator circuits on a copper plate for an RF design class using the dead-bug method. I know that short leads between components is preferred over long leads, but why is this? I heard ...
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### Which is the best material to create a magnetic field?

I'm trying to create a magnetic field and I'm also trying to induct electricity wirelessly to a light bulb. What I have to do is create a round coil but I'm not sure what is the most conductive ...
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### Electricity not conducted by copper wire

Im am quite stunned as to what might be wrong. electronics beginner I bought today some copper wire, 20SWG /0.9MM from maplin (UK), for a project I am working on. There is no power going through ...
293 views

### Stripboard without copper tracks?

I bought this stripboard on Ebay. It said "Veroboard" so I had thought it would be with some sort of tracks: http://www.ebay.com/itm/281342062542 Turns out there's copper around the holes but there'...
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### Can electrical wires be ruined by overheating?

I have a friend that works with automotive mechanical sorts of things, and he told me that he had a pair of jumper cables that was ruined by too much current; it wasn't that the insulation melted: he ...
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### Using distribution transformers vs direct connection to primary switch gear

I am trying to learn more about transformers and low voltage electrical distribution. Say you have a medium sized industrial building with a primary switchboard feeding several load centers ...
3k views

### Hot wire cutter. Can I use copper wire

I am not from an electrical background and this might sound silly. What I am trying to do is create a hot wire cutter to cut thermocol(Styrofoam). The sugestions from internet is to use Nichrome but I ...
2k views

### Why is there copper on the side of this package?

I'm searching around digi-key when I noticed one of the MEMS oscillators has these copper pieces on the edge of the package: I'm not talking about the pads, I'm just talking about those little ...
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### I just bought a one-earbud headset with a microphone, but the jack is too small! I cut it open, what do the wires do? [closed]

So, yeah, this is my first question, yay, but I still have a problem, boo. I was on a rummage sale spree, so-to-speak, looking for a new pair of earbuds as yet another cheapie pair has broken. I ...
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### Soldering thin polyurethane covered wire

Is it possible to "solder through it" or does it have to be fully stripped? The material is 0.15mm copper wire.
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### I need to create a planar inductor with a specific value of 28 nH on a 4-layer PCB. How do I determine the proper trace geometry?

I am using a Linear Technologies LT-1534 part an need to create a planar PCB surface inductor with the specific value of 28nH; i.e., the inductor will be a copper trace on the PC boards Top Surface to ...
2k views

### High voltage cable cross section

What kind of power and voltage can the cable in the photo possibly drive and why is it composed of a lot of small cables? What if the diameter of the single copper cables were a little bigger? How ...
229 views

### How does this prototyping style work?

I'm a little puzzled about a prototyping style I've seen used recently. Here is an example picture of a circuit made in this way: Can someone explain the process of making a board like this? Why are ...
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### How does a digital sound card's electric circuit make different pitches, etc. measured in just electrons? [closed]

I was wondering how hardware engineers, electrical engineers, or any and all inbetween design a circuit diagram for something that measures pitches, tones, etc. all in the form of bits/bytes and ...
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### Coupling mechanisms

What are some mechanisms that one material can be coupled electromagnetically to another, other than basic tranformer action? The model I'm considering is a high current electrode, about 1.5m wide, ...
271 views

### Current carrying conductor axially through a copper ring

What effect would a copper ring around a current carrying conductor have on the current in the conductor? How can I go about mathematically modelling the current in the conductor? Details : The ...
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### Is it better to have a poor top layer copper pour or no copper at all?

For a few small 2 layers boards I'm doing, I'm using the top layer for parts and signals and a ground pour on the bottom layer with no or very short traces, based on comments and answers to my ...
5k views

### Heating wire filament with low voltage / amps

Is it possible to heat either nichrome or copper wire (both 40 awg) with the following low-power delivery of 3.5 Volts, 7.4mW and 2.11mA? This is very low power delivery and we're wondering if 3 ...
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### PCB Design Considerations - Copper Pouring

So after a very long effort, I think I've finally come towards the end of my PCB board design. It's a two layer board with no ground or VCC plains (Re-routing is not an option) as I can't go though ...
2k views

### Why are copper tracks orange-gold?

I have in front of me a raw PCB. The surface mostly has three colors: dark green, orange-gold and white. As I understand, the green is resist, the orange-gold is copper, and the white just the silk ...
2k views

### Why does water short out PCBs? (i.e. Why doesn't electricity follow the path of least resistance?)

If copper is more conductive than water (at any reasonable PH), submerging copper electronic circuits in should have no effect, as the electricity should continue to follow the path of least ...
350 views

### PCB Design - Copper Pour

I need some guidance on how to begin troubleshooting a specific problem with a bareboard. Board Info- Size-22"x26" Laminate-ITEQ Layers-30 In addition to standard bareboard ET (10v with 10Mohms ...
510 views

### Encoding delay of Ethernet and the relation to cable frequency rating

I asked a question here called "Speed of electricity (signal propagation?) through copper for communications delay". I wanted to know how long does it take a signal to travel down a length of Cat5e ...
2k views

### pcb damaged, broken copper any ideas?

I was trying to solder a new capacitor on my pcb and I had problems. At the end I think I burned the copper under the pcb mask and I am wondering if i totally destroyed my pcb. Here is a picture: ...
1k views

### How can I determine the resistance needed to heat a wire to a specific temperature? [duplicate]

Possible Duplicate: How do I calculate the temperature rise in a copper conductor? I want to have a AA battery heat up a copper wire .12mm diameter, but want it to heat up to 302°F, not ...
6k views

### reference source for copper conductivity vs. temperature?

I am looking for a curve for copper conductivity vs. temperature over the -55°C to +180°C range (covers std. ranges of semiconductors plus NEMA class H insulation in the case of magnetics / ...
2k views

### about power supply on what length of copper wire we should use

Could you help me on the equivalent current of three phase alternating current having 400v( volt ), 530 kw power and the available cross-sectional area of a copper wire, its length 350 m for carring ...
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### Coils! Does the material used matter?

I've been making some coils with wires and I find out that sometimes they work and sometimes they don't work at all, the inside of those that don't work are some what more "silver-ish", more "metal-...
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### How do I determine the area of copper needed on a PCB to provide adequate heatsinking for a power SMD MOSFET?

I am planning to use the IRFR5305PBF Power MOSFET (http://www.irf.com/product-info/datasheets/data/irfr5305pbf.pdf) to switch on a load. I have determined that I need an external heatsink with Rthsa &...
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### multi-layer board copper pour

I have a 6-layer board where the internal 4 planes are +15,GND,VCC,-15. I was wondering if there was any advantage to doing a copper pour on the top and bottom layers? I would probably leave them ...