Questions tagged [thermal]

Relating to temperature rise, the flow of heat, or cooling of components

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1answer
327 views

Difference in thermal measurement with thermal camera and thermocouple

I hope this is a proper place to ask the question. I am using two different methods to do a thermal measurement on a flyback power supply that has a planar transformer. First I used FLIR E60 thermal ...
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781 views

Water Temperature Sensing with DHT22

This question may also be asked in physics stackexchange, but I'll try my luck first here. I want to set up a water temperature sensor system. My temperature sensor will most probably be DHT22 due to ...
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1answer
357 views

MOSFET pwm circuit question

Good day, I have duplicated this circuit using a 40106 hex inverter to drive a motor using pwm. The only difference in my design was to switch out the transistor stage for an Irfz34n MOSFET. The ...
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1answer
80 views

Passing cables through a thermally insulated wall

I am constructing a temperature control chamber. Of course, thermal insulation, is key in the development of the chamber. The idea is to insert different electronic circuits inside and study their ...
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1answer
55 views

Doubt on the Voltage Regulator Application with LiPo Battery

If I have a LiPo battery with the maximum voltage of 12V and I want to use it to power a 5v(L7805) voltage regulator. Assuming the maximum current passing through the regulator is 500mA. From ...
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213 views

Solar panels burning down 12 volt appliances

I have two solar panels. One is 310 watt 39 volt 8 amp and 2nd is 250 watt 37 volt 8 amp. The 310 watt one burned down a 12 volt fan, then I bought a 24 volt fan and have operated it on both panels ...
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2answers
668 views

What would cause a voltage regulator to output much lower than its rated voltage?

I am building a 12v power supply based on this. Main changes are use of two 2,200uF filter caps instead of one, and 7812 (12v) regulator instead of 7809. Plugged it in the first time and the ...
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3answers
2k views

How to determine temperature grade for automotive electronic components?

When developing a new automotive electronic component, the component needs to be certified to withstand certain temperatures. There are several standards that list methods of testing, such as ISO ...
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4answers
722 views

Proper board layout for high power SMT FETs

I came across an SMT FET (IPT015N10N5ATMA1) that has an output of 300Amps in a rather small form factor. Are thermal vias enough to get heat away from the 8-PowerSFN package? Or would something like ...
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1answer
755 views

Will LD33V voltage regulator overheat with 12V 2.4A dc input?

The circuit works and it provides a stable 3.3V output, but it heats up and I'm afraid it can overheat and cause problems.
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What mad solder type is used for BGA?

Having nothing to do in my workshop, I decided to practise my skills a bit. I digged up a scrapped graphics card from the junk box and decided to try to desolder the RAM-chips (BGA) after seeing how "...
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1answer
256 views

How does thermal runaway occur in a battery?

I've always learned that when a wire or conductor heats up it'll increase resistance due to the free electrons crashing into other vibrating electrons. So I'm confused how thermal runaway has its ...
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2answers
2k views

Junction to board thermal resistance

The Junction-to-case (bottom) thermal resistance of the TPS7A4701 LDO regulator is 1.7 °C/W. It is explained in the TI's app note "Semiconductor and IC package thermal metrics" that this metric refers ...
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251 views

RDS(on) of DMN3010LSS MOSFET transistor

I am a bit confused about Figures 3 and 4 in the datasheet of the DMN3010LSS MOSFET transistor: Why do they show how the Rds(on) varies as a function of the ambient temperature TA? I thought that the ...
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732 views

MOSFET power wattage

I am analyzing the thermal dissipation of the FDB33N25 MOSFET - datasheet The procedure I usually follow is as stated: $$I_{d} = 15~A (requirement)$$ $$R_{ds} = 92~m\Omega$$ $$\Theta_{ja} = 62,5~K/W$...
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638 views

Thickness of thermal relief on copper pour

I am working on designing a pcb that will have a copper pour. I have selected to use thermal reliefs to connect the pour to pads, but I am a little confused on the thickness. Should each spoke of the ...
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2answers
264 views

IS heat the only thing keeping CPUs from a faster clock rate? [closed]

Is heat the only thing that keeps CPUs from having a faster clock cycle or are there other limiting physical factors which keeps CPUs under 3~5GHz?
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648 views

Pyrometer device compatible with arduino

I am an undergraduate Mechanical Engineer and currently I am using a laser which heats and melts a surface of any material (plastic, metal etc) which is formed in powder. Although, I have managed to ...
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8answers
2k views

Modelling heat transfer from Power LED to metal bar

I'm playing around with workplace illumination and have developed a 20 V –> 38 V PWM'able constant current source to drive my power LEDs (max power about 64W). So far, so good. However, I've nearly ...
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87 views

Are microprocessor pin current limits dependent on frequency?

I have blown a single pin on an Arduino Mega 2560. This is the 'step' pin of the Z axis on a 3D printer. The stepper driver is configured for 64 micro pulses per step (25600 per revolution). The ...
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2answers
3k views

Is a thermally conductive pad always useful between TO220 and heat-sink?

I have a doubt about heat-sinking that I could not solve by surfing the Web. My doubt arised when mounting a TO220 package on its heat-sink using these dirty cheap pads, but actually it has quite a ...
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1answer
167 views

most resistant substrate layer to embed a specific wire

I am in process of embedding a wire in a choice of substrates. I would apply voltage so much as to heat it (the wire) to 220 degree Celsius max. What are the best choice of substrates I can use so ...
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162 views

How to make a incandescent lightbulbs filament withstand shock?

I want to know, is there a way to make a tungsten lightbulbs filament withstand a mass amount of thermal shock while still producing a vast amount of heat?
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3answers
197 views

Cheap precision sense resistor

I need a precision low value sense resistor to make current measurements e.g. 10R 0.01R. Looking for precise resistors e.g. Vishay, show that these are expensive e.g. $35 for a single 0.001-0.005% ...
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72 views

Temperature raise inside a case

I'm using a D2PACK triac model ACST830-8G datasheet According to datasheet (over 1cm2 cooper) it supports 2A, considering Tamb = 43° TABLE GRAPHICS I want to use this triac inside a case and ...
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1answer
1k views

N-channel mosfet calculations

I am in the process of selecting a suitable FET to switch a resistive load (LEDs), triggered by a 3.3v MCU signal. The schematic would be: However, I am having some trouble with my (rough) ...
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1answer
208 views

Is there anything wrong with this heat sink design? [closed]

If not, is it any better that the conventional fin-based heatsink? It attaches at the bottom, and looks exactly the same in the back. It is supposed to be a passive cooling type heat-sink, therefore ...
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2answers
131 views

How to calculate the time that a piece of wire can last before it melts when constant current is applied

How to calculate the time that a piece of wire can last before it melts when constant current is applied? Assume it has a fixed cross-sectional area, I know longer the wire quicker it will melt, but ...
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2answers
270 views

Temperature Controlled Heat Generating Device (40-80 deg C)

I'm a physician doing benchtop experimentation. Background: Tissue is known to coagulate at 43 degrees celsius (CEM 43 thermal tissue damage index). I'm seeking to find/build a temperature controlled ...
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3answers
710 views

LDO selection based on power dissipation

Perhaps You could help me confirm my thermal discussion on choosing appropriate LDO? MIC5225, a 16Vin and 150mA output current quaranteed LDO. So, parameter-wise I would guess that I could use this ...
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3answers
454 views

Best way to electrically and thermally connect a FET to an Aluminum heatsink

I am designing a drive and need to electrically and thermally connect the tab of a series of FETs to an aluminum internal heat sink that is also used as an electrical bus. It seems the best way to go ...
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1answer
228 views

“Simple” thermal analysis of component on PCB over time

I'm trying to be pragmatic about designing a PCB and circuit that will have to dissipate heat. It's pretty simple: a surface-mount power transistor charges up a 4F 5v supercapacitor with a roughly ...
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0answers
2k views

LTSpice: How to save output from multiple .op runs

So this is a somewhat complicated question... I am trying to run a .op simulation (DC operating point), using the .step command to iterate through a bunch of component values. I would like to save the ...
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1answer
1k views

Altium: How can i add thermal releif to the GND footprint of one component?

I want to have the pad that is connected to ground on one component to 'relief connect' on altium but have all other components whos pad is connect to ground to 'direct connect'. Is this possible?
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623 views

Thermal relief for thick PCB traces

A PCB trace that carries considerable current (~5 Amps) needs to be wide, on the order of 4mm. I am concerned that this wide and thick (70mil) trace may cause problems during hand soldering, but can ...
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3answers
9k views

Can an infrared thermometer (IR gun) be used to measure the ambient room temperature?

I know the principle of an IR thermometer, but have one question regarding that are as below. As an IR thermometer senses the radiated IR waves from external bodies coming in their field of view and ...
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786 views

Case to heatsink thermal resistance with multiple MOSFETs

I have 3 paralleled MOSFETs which will be attached to a single heatsink. I am trying to calculate maximum possible power dissipation and required heatsink thermal resistance Rsa(sink-ambient). I ...
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2answers
438 views

Providing a One-way Heat Sink [closed]

How would one design a component that allows heat to flow freely in one direction only, while preventing heat conductivity in the reverse direction? I imagine such device might be thought of as a "...
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1answer
434 views

Relation between thermal conductivity factor(k) and temperature coefficient of resistance(α)

I'm trying to understand the thermal parameters affecting circuit design. I came across two different parameters. thermal conductivity factor(k) which is related to thermal impedance. The link to the ...
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77 views

Closed enclosure thermal design the right way

I have a circuit board that works quite well (processor, screen, power supply). It has been tested successfully for an open aluminium enclosure, but now it will need to fit a rugged 100% closed box. ...
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2answers
814 views

PCB design for LEDs on aluminium board in Eagle

I'm making LED light panel which will contain lots of high power Surface Mount LEDs connected in series. I'm using the LUMILEDS Luxeon Rebel Series LEDs which has three pads on each LED, an anode, a ...
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158 views

Extruded heatsink question

I have few questions about a general extruded heatsink. As example, we can use this from Farnell. Let's say it is long 20cm with a given shape, sold to have a Thermal resistance of 10°C/W. Q1: (...
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157 views

Could you double the speed of a GPU by doing half the work?

Is the thermal impedance from a GPU's wafer to the heatsink low enough that you could get close to doubling the clock speed if you halved the duty-cycle (render 50% of the full-TDP framerate). An ...
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1answer
226 views

IC thermal breakdown [closed]

Why does my power op amp IC (TI OPA549) thermally malfunction? IC works electrically perfectly, no oscillations or anything. By thermal malfunction I mean that Rj-c thermal impedance rises from ...
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1answer
2k views

How can I get the actual heat values from a thermal camera and know the pixel values?

I'm working the the FLIR thermal camera and using the code provided by Pure Engineering. I've recently run into a problem with the images provided by the camera because I realized that the pixels are ...
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1answer
5k views

How do I edit thermals on pads in Eagle?

I have a ground plane and would like to increase the number of gaps in the thermals of a ground pad. I have more than 9 amps running through this ground pad and need to increase contact. It looks ...
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36 views

heat generation by semiconductors

I am trying to do a power analysis of an IC. It is an I2C isolator. Now, there are 2 I2C buses (hence bidirectional). I want to analyse the effects of its working on the temperature. The ambient temp ...
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1answer
378 views

CPUs and GPUs temperature ranges

Every integrated circuit, like any other component, have a working temperature range. The minimum ranges are in the commercial grade (if I did dot forget something), while the military/aersopace grade ...
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14k views

Optimize heat sink design - connect cooling pad on PCB backside by vias

In one of my current projects I'm using an MC7805 in a D2PAK package to generate my logic supply of 5 V from an available 24 VDC supply. The current required by the circuit is 250 mA. ...
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2answers
481 views

How to decide the Temperature range of an IC?

I am using a MAX3241E ic in a device that has to run 24x7 out in the open. I am facing a problem deciding the temperature range of the the IC. Since it is out in the open, the ic has to withstand the ...