Questions tagged [heat]

Thermal energy; where it comes from, and how to keep it from damaging components

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103
votes
6answers
63k views

My linear voltage regulator is overheating very fast

I'm using a 5 V / 2 A voltage regulator (L78S05) without a heatsink. I'm testing the circuit with a microcontroller (PIC18FXXXX), a few LEDs and a 1 mA piezzo buzzer. The input voltage is aprox. 24 ...
15
votes
8answers
66k views

Why is it dangerous use a coiled extension cord

What aspect using a coiled extension cord makes it more dangerous than using an unrolled power cord. Many fire safety websites reference that an extension cord should not be used while coiled. Is ...
5
votes
2answers
18k views

Smartest way to use current limit using LM317?

As i understand, using this circuit: Will cause the current to go right through the POT and resistor, which will generate a lot of heat. Is there a better way to use current limiting with LM317 ...
7
votes
1answer
5k views

How do I tell what gauge wire I need?

I've been working on providing power for high current applications for my project. I'm working on a project with high current (or at least compared to what I'm used to...) What a lot of people point ...
27
votes
7answers
39k views

How to carry high current on PCB

I need to pass high current on some part of my circuit. I used an online PCB track width calculator to see that required track width is about 5mm and minimum clearance is 1mm, which makes it about 7mm ...
22
votes
2answers
13k views

What is killing my MOSFETs

This is my first post here on electronics stackexchange. I am a hobbyits in electronics, and a professional in programming. I am working on a inductor circuit to heat a workpiece. I have a working ...
27
votes
6answers
20k views

Why exactly do chips start malfunctioning once they overheat?

Once a chip overheats it can start malfunctioning - for example many programs may start failing once some or all parts in a computer overheat. What exactly happens that makes chips malfunction when ...
20
votes
2answers
102k views

Is it possible to calculate how much heat dissipation and temperature rise will take place in a resistor

Suppose I have a 100 mAh battery at 20V. I connect a 1000 kohm resistor across it. How much heat will be generated and how can I find the temperature rise in the resistor? As the battery operates I ...
5
votes
2answers
6k views

Thermal management of MOSFETS in TO-263 package

I'm using SUM60N02 MOSFETs in TO-263 package for my car battery charger power unit. In datasheet they have specified thermal resistance: Junction-to-Ambient - 40 °C/W when mounted on 1" square PCB ...
0
votes
2answers
919 views

How do I correctly estimate heat output for heater wire

This is based on a problem that came up today. During the course of this problem I realized that I wasn't so sure I understood the relationship between wattage and heat produced. In the past we did ...
29
votes
4answers
18k views

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 &...
21
votes
17answers
5k views

How to 'fix' this in an enclosure without glueing?

I have an enclosure, and want to fix/put a STM32 inside, a relay and probably later a small circuit board. However, the STM (STM32F103C8T6) and the relay do not have holes to fix them... and I do not ...
13
votes
2answers
3k views

Warming PCB in a low temperature environment

I have to develop a microcontroller circuit that will run at low temperatures (as low as -60C). I want to heat the FR4 PCB board until it reaches the commercial temperature range above -40C. I found ...
7
votes
4answers
9k views

Setting heat on electric stove

This may sound like a strange question, but its bothered me for a while: I assume electric stoves (the ones with the coils that get red hot) work just by having a resistor that gets hot. If it's ...
12
votes
4answers
17k views

Multiple resistors in series instead of using a single resistor has any advantage: heat produced by the resistors of diffent watts are different?

I have two doubts, requesting you to answer my doubts separately. :) 1) I need a resistance of 'X', so is it better to use a single resistor of 'X' value or multiple resistance of r1+r2+r3='X'? What ...
11
votes
4answers
4k views

What exactly gets “worn out” and damaged by heat?

It's quite common knowledge that heat is bad for electronics. That constantly high temperature decreases the expected lifetime of computer parts even if they are not overheating per se. If, for ...
8
votes
4answers
15k views

How does electricity produce heat, and where do the electrons go?

When electrons flow through a conductor it is subject to resistive loss, which has the unfortunate capability of producing heat from this current, leaving us with less current in the other end of the ...
5
votes
6answers
976 views

What's the rationale behind these warnings about extension cords?

(Disclaimer: I've read the help center and I do understand that this is bordering on off-topic since it's about consumer devices. However I hope that I've managed to make enough on-topic by asking ...
5
votes
3answers
21k views

Calculating the DC voltage and current needed to obtain certain heat with a resistor

What formulas can be used to calculate how much volts and current is needed to get a resistor to heat up to a certain temperature? I need to get a resistor (or a few next to each other - for more ...
9
votes
2answers
17k views

Calculating Power Loss in Switching Power Regulator?

I am new to the construction of DC/DC power supplies (still a university student) and have built basic supplies using simple linear voltage regulators. I have recently discovered the world of ...
12
votes
5answers
1k views

Enclosure best air flow profile

I'm in final step of a project an I need some advice about what heat evacuation profile should I use to place three fans for cooling, I have four alternatives as shown in the diagram but I don't know ...
6
votes
1answer
2k views

Help with Metal-Core PCB

I have designed several typical FR4 PCBs in the past. I am interested in designing my first metal-core PCB (MCPCB) for a circuit that requires high heat dissipation. I am looking for any helpful ...
6
votes
2answers
754 views

What are the physical mechanisms of core loss, and how can they be minimized?

Suppose you have an inductor in a boost converter. The core gets hot. Why? What are the physical mechanisms that cause core loss? Eddy currents? Magnetic domains flipping? Coupling to materials ...
7
votes
3answers
2k views

What is the coolest way (using passive cooling only) to step 12V DC down to 5V DC

I'm building a project that needs both 5V and 12V rails which will draw about 1A on the 12V and 0.5A on the 5V. I was thinking of using a 7805 to produce the required 5V but this could generate some ...
7
votes
1answer
10k views

Why is my N-channel MOSFET getting very hot and the power it provides to device increases with temperature?

I have a fairly simple situation: N-Channel MOSFET with base connected to Raspberry Pi's 3.3V source connected to ground and Drain connected this way: +12V ----> Vacuum Cleaner (60W) -----> Drain. Guy ...
6
votes
1answer
2k views

Is CPU/GPGPU heat dissipation quadratic in clock frequency?

In the following article on overclocking a Pentium from 1GHz to 5GHz using liquid nitrogen: The 5GHz Project, there is an assertion that "Heat dissipation rises exponentially during extreme ...
5
votes
2answers
2k views

Why is my power MOSFET heating up when on?

I'm switching a 12V 500mA resistive load (LED strip) with a IRF540 MOSFET and it's getting very hot when it's on and conducting. This confuses me as MOSFETs are ...
5
votes
3answers
2k views

Can I draw power for a component while this charger is charging the battery?

So I am working on a design for battery-heated wrist warmers. My mother has Reynauld's and arthritis, and as winter approaches it gets much worse. My basic design is that I will take a form-fitting ...
5
votes
3answers
204 views

How does current turn to heat/light? [duplicate]

When resistors are serially connected, the current is the same through the whole circuit. To my knowledge, the electric current is electrons traveling. Also, the power of the generator equals the ...
3
votes
3answers
10k views

Does a resistor in an AC circuit produce the same heat as in a DC circuit?

Does a 1k ohm resistor produce the same heat in a AC circuit which has an rms voltage of 10 volts (60 hz.) as it would in a 10 volt DC circuit?
3
votes
3answers
685 views

Regulator cooling in a confined space

I've designed a simple PWM RGB LED slow fader to be used as a garden lighting effect. My circuit works great, but I under-estimated the amount of heat that is generated by the 7805 linear regulator. ...
2
votes
2answers
2k views

If I pass electricity through heating coils will it make heat?

This may sound like a silly question. But if I strip some wires added the connectors and connect them to a heating coil will it heat the coil up? What else would I need to produce heat?
5
votes
1answer
351 views

240V 5A PCB traces - stitch double sided or not?

If I have traces connecting a relay to an terminal block (10A relay, 6A terminal, 5A expected maximum load) and I double the traces up on both sides of the board (mirror the traces on the top and the ...
3
votes
1answer
3k views

L293D overheating

I have an old RC car. I removed all electronic from it, just left the plastic and the DC motors. It has 2 DC motors(1 for moving, 1 for left/right). I decided to attach arduino to it, while ...
2
votes
1answer
258 views

What does a beginner need to know to build a programmable heater based on resistance heating?

To build a programmable deep fryer, as a learning project for more serious checmical reactors, I need to build a programmable heat source that can be controlled in response to sensor readings and a ...
2
votes
2answers
18k views

Is over charging the phone while using headset risky [closed]

I recently came across a post in social network which was claiming to be a news about a girl getting electrocuted during her sleep with her headsets connected to the mobile and the mobile being ...
1
vote
3answers
488 views

Making Hot and Cold room at the same time with Peltier stack

I am thinking about 2 small boxes with peltier stack middle of them to get a cold room and hot room at the same time. Is it possible to get -40 degree celsius cold room and 100+ degree celsius hot ...
1
vote
1answer
157 views

How does length affect current carrying capacity

Will a wire have increased current capacity if the length is sufficiently small? The reason I'm asking is that when doing PCB layout the vias often has thermal relief, which are small traces going ...
1
vote
3answers
514 views

How to to Use a Nylon Shoulder Washer?

I'm somewhat curious as to how to use a nylon shoulder washer with a bolt. There is an example of this here (https://electronics.stackexchange.com/a/45579/95654), but I can't figure out how it would ...
1
vote
2answers
1k views

Keeping the output of a heated LM317 constant

I have built a power supply using an LM317: simulate this circuit – Schematic created using CircuitLab When the supply is on for a rather long time (several hours) with a respectable load, the ...
1
vote
2answers
595 views

LD1117 Heat Sink

I'm about to put a LD1117 Low drop-out regulator in SOT-223 package into one of my projects and wonder if the heat sink is internally connected to anything. Unfortunately the data-sheet doesn't ...
1
vote
1answer
2k views

Designing a copper plate heat sink

I’m trying to see if a copper sheet I have with me (25 cm X 30 cm, 0.05 cm thick. There's a 6 cm X 6 cm square hole in the center to place a lamp.) is sufficient to keep 36 luxeon rebel LEDs (mounted ...
0
votes
2answers
225 views

PCB coating for a high temperature environment

What PCB coating is good for a high temperature environment (my environment is about 30-70 C), and is available in a spray can or so that is easy to implement without need of a device/machine?
0
votes
2answers
52 views

The Relationship of Power and Heat to Length of a Resistor

I have two sections of nichrome wire. They are identical in every way (gauge, etc.) except one is twice as long as the other. If I made it so the short nichrome wire received about 8.485 V and the ...
0
votes
5answers
464 views

Transistor Collector Heats Up

I used power transistor to drive high power LED (used in streetlights) I added resistor between the Transistor Collector and the LED to verify which part of the transistor causing too much heat, and ...
0
votes
1answer
123 views

Controlling an electric water heater

I'm trying to control the temperature of water heated electrically. On devices sold commercially I see that temperature is not being controlled, and the heating elements are either turned on or off (...
0
votes
2answers
107 views

Dc heater that will/should blow hot air

I was just trying to lift a toy motor off the ground so mounted a toy propeller and tested it, i think it would have lifted(without battery weight) but i didn't bothered balancing it. Final result ...
0
votes
0answers
81 views

4-20mA current loop - transmit sensor reading

I am working on design loop current transmitter- to transmit reading value from thermocouple sensor using below design. I measured co-junction temperature using NTC instead of RTD. During applying ...
0
votes
4answers
394 views

How to Generate Heat with Joule Effect? [closed]

I'm going to build a coffee heater for a school project. I know I have to take advantage of the Joule effect (Joule heating). I am restricted to using a resistance between 330 Ω and 1 MΩ. The ...
0
votes
3answers
2k views

Determining Resistor for Heating Element

I am attempting to run a Molybdenum heat coil. The best I can tell it is 0.3-0.4 ohms per rack and I would like to run say two racks at 230V at 3.9KW (so it doesn't trip my 230V 20 amp breaker). Does ...