Questions tagged [heatsink]

A heatsink dissipates heat into the surrounding air and thus provides cooling.

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What is meant by the statement "Local bypass capacitors are needed to control EMC coupling with heat sink"?

During a talk, not sure what the speaker meant by the statement " We need to add local bypass caps to control EMC coupling with heat sink" He was referring to the MOSFETs in synchronous ...
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Where can I find large thru-hole heatsinks like this? [closed]

I'm doing a project with an OPA541 amplifier, and I need to find a heatsink similar to the one in the pictures: But I only found small ones with a screw hole and legs for soldering, none of the large ...
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1 vote
1 answer
102 views

Can a CPU heatsink be used to cool a TO-3P or a TO-220?

I want to know if my thermal design is appropriate for dissipating 72W of heat while keeping the junction temperature below 150 °C (I am trying to cool an SFH154 that comes in a TO-3P package). My ...
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2 answers
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Step-down conversion materials

I have an ac adapter on which I would like to reduce the output, from 24 vdc to let's say 6 vdc. What type of diodes should I use and how many? What about heat dissipation?
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4 votes
2 answers
154 views

Copper braid as heatsink

Somebody recently asked me about this headlight: https://www.hsd-il.com/products/h7-72w-8000lm-led-car-headlight-bulbs-cree-led-chips-6500k-drl-copper-belt-headlights-12v-24v Interesting. I'm not ...
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1 answer
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What is the black, finned, metal part in this picture of a board?

Can someone explain what this black part is? This a WLAN module.
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2 votes
1 answer
87 views

LED lights become darker? [closed]

I build myself a light with many small LEDs. They are quite powerful. I superglued ever LED board (the LEDs where in parts of 3 on a small circuit board) to an aluminium piece to dissipate the heat. ...
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1 answer
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Possible fixes to a power supply thermals issue

The question applies to a buck converter design on my board: Here is a 3D view of this section: Layout of this section: L1: L2: Layer 3 is power and layer 4 is again a full ground plane. Here is ...
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Is it safe to connect metal body capacitors with a metal heatsink?

I have multiple metal case capacitors that I need to cool. The thermal tape I use is conductive (carbon based). Also larger heatsink on the left might touch capacitors on the left side. The question ...
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1 vote
2 answers
31 views

How to use units given for heatsink thermal resistance?

In looking for a heatsink I came across a company giving the thermal resistance of extrusions in °C/W/3in. How do I use this? Say I use an extrusion with a specification of 1.5 °C/W/3in and get it ...
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Does voltage drop resistor affect power dissipation?

I need to power an RFID from 24 V DC voltage. The RFID requires max. 9 V and max. 120 mA. The RFID suggests a 7809 linear voltage regulator. I thought too much and I want to use a 7809 because if I ...
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2 votes
1 answer
175 views

Why is my DC/DC converter getting super hot?

I need to supply an evaluation kit at 32 VDC +- 10 % from a 48 VDC battery. The power supply of the kit is rated at 60 W with spikes at 150 W lasting 100 ms (it controls motors). I have choosen the ...
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1 answer
68 views

Heat sink thermal resistance

Is there any way to figure out the thermal resistance of a heat sink without using a datasheet or using it in an actual circuit? I mean, simply by knowing its dimensions and material.
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-1 votes
1 answer
66 views

Heatsink size calculation

Let's say I found a random heatsink with no name or model or anything else from which I can find a datasheet and get its thermal resistance. Therefore, simply by knowing its sizes, how can I calculate ...
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0 votes
1 answer
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How can I specify in Altium to leave out the dielectric layer for a portion of the board?

I am trying to replace the dielectic layer in just a portion of the board and instead have that just be more copper. The idea is to essentially allow the PCB to use anything it lays flat on to be a ...
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1 answer
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How should fuses be used for MOSFET temperature protection?

I am using high voltage MOSFET in TO-220 package with a heatsink like this one: Under normal conditions, the temperature of heatsink does not exceed 90 degrees. My MOSFET can run up to 120 degress ...
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1 answer
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How do I use a heatsink in a sealed enclosure?

I'm working on a project with a set of individual LEDs (datasheet) permanently set up in an outside setting in winter, at night. I need to build separate enclosures for each of the LEDs because they ...
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2 answers
111 views

What power supply do I need for this LED driver?

I'm putting together a project where I'll be driving 4 x 10W RGB LEDs (these ones) with one PicoBuck LED driver. I'll be using all three channels on the LEDs at the same time and controlling dimming ...
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3 answers
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Heatsink needed to keep my resistor from damaging due to heat

I am looking to find an appropriate range of heatsink selections to maintain my resistor from damage due to heat. I am using a flat plate (SS) resistor from ARCOL (TFBR900). It is rated for a 900 ...
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0 answers
77 views

Attach heat sink to cpu cooler in order to decrease CPU temperature

The best SMALL FACTOR cpu cooler that I have found so far is this one: I am building a portable PC; therefore, the smaller the better. I have already checked the specifications and that cpu Noctua ...
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12 votes
4 answers
2k views

Why are these SMD heatsinks designed to not touch the IC?

I am using a 7106DG heatsink to dissipate the heat from an IC. It looks just like in its datasheet: It leaves a gap between the IC and the heatsink, and the datasheet even mentions it, but I guess no ...
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1 vote
1 answer
71 views

Copper Weight/Copper Pour Usability in Thermal Management

I'm trying to think of a way to decrease the temperature that my PCB is running at, but I don't want to add a heatsink if I don't have too since I want this board to have as low of a profile as ...
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2 votes
3 answers
172 views

How does junction to case thermal resistance depend on PCB?

Shouldn't the junction to case (top or bottom) thermal resistance depend only on package or IC internals? How do the PCB details play a role as mentioned in footnote 1?
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  • 2,051
6 votes
2 answers
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Why is the thermal resistance of copper shown higher than FR4 in below snap?

I see similar W and L for both Cu and FR4. Why is the Cu thermal resistance shown higher than FR4? Is it because of Ounz difference? 1 Oz Copper= 34.8um. FR4 seems to have more thickness-> How ...
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1 vote
1 answer
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How to remove and replace fiberglass based thermal conductive adhesive tape/sheet on heat sink

I'm working on troubleshooting a PSU and came across a fiberglass like thermal conductive adhesive tape/sheet (soft beige) in between the TO-220 power MOSFETs and the heat sink as shown in the photo. ...
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9 votes
4 answers
2k views

Installing heatsink on a bridge rectifier: which side of the rectifier should it be installed on?

I'm going to install a heatsink on a KBU810 bridge rectifier. As the picture shows, the leads are closer the face with markings on it. I wonder if one of the two faces is the preferred site for ...
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3 answers
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How to calculate heatsink for this power supply?

..to be updated I will use a power supply inside an enclosure. But I saw some people are screwing these supplies to heatsinks where the bottom of the supply faces the heatsink. But nothing is ...
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1 answer
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RF Module Gets Too Hot

I'm using the RFM98PW-433S2 1W(+30dBm) 433MHz RF module. After a couple of minutes of working the module gets to above 70°C temperature. Probably reaches 90°C and above after couple more minutes. I ...
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6 votes
2 answers
1k views

Is raising a hot Zener diode from the PCB (for better ventilation) a bad idea?

Whenever I rework a Zener diode which has been running too hot (i.e. failed), I like to replace it with a higher-power equivalent when possible, and (if through-hole) raise it slightly off the board ...
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1 vote
3 answers
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How can a complex shape's heat sink thermal resistance be determined?

I need a heat sink with a thermal resistance of 0.7 °C/W/3" or less. C/W/3" represents how many degrees Celsius per watt a 3" long section of heat sink can dissipate without exceeding a ...
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3 answers
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does a larger or smaller C/W thermal resistance value indicate greater heat dissipation

I need help understanding the heat sink thermal resistance specification. Does a larger thermal resistance value indicate it will dissipate more or less heat?
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2 votes
2 answers
1k views

Can PCB dissipate heat from MOSFET so that a heatsink is not needed

I am using a DMP3007 as a reverse polarity and over voltage MOSFET. The maximum planned load is 10 A and voltage may vary as the load is a constant current load. simulate this circuit – ...
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59 views

Grounding of heatsink for SiC MOSFETS half-bridge

I was working on SiC Mosfet half bridge for dual active bridge, Each half bridge has two SiC MOSFETS Rds0n=0.035 mohm , the bus voltage peak is 600VDC on the primary side. and I was wondering should I ...
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  • 303
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2 answers
253 views

Electric-grade gel / silicone to provide physical protection for circuit boards from damage

Not looking for a brand or product (unless allowed to ask) just the generic name for electric-grade gel / silicone that can be poured on the circuit board or embed the circuit-board in it. It would ...
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0 votes
2 answers
157 views

Can two IRLZ44N MOSFETs in parallel handle a current of 20 A without heat sink?

Can two IRLZ44N MOSFETs in parallel handle a current of 20 A without a heat sink? The Vgs command is a square wave at a frequency of 70 Hz. Do I need to attach two big heat sinks or not? Will my two ...
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0 votes
2 answers
69 views

Understanding Power Diodes and Heatsinks

I am working on reverse engineering and understanding a circuit board from the 1970s. I don't have a schematic diagram from the manufacturer. This board has an unmarked power diode that has a flange ...
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6 votes
3 answers
591 views

What's the right replacement for vintage "glass cloth insulation" that transfers heat in Variac?

I ripped apart a broken 1950s-era Variac autotransformer to diagnose an internal short in the core, and found a layer of gooey insulating fabric mat between the coil/taps and the mounting plate: The ...
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2 votes
2 answers
98 views

Is my heat sink calculation for the LM317 correct?

Using the formula PowerDissipated = (Vin - Vout) * Iout where: Vin = 12 V Vout = 2 V Iout = 450 mA Power dissipated = (12 - 2) x 0.45 = 4.5 W And heat sink value = (...
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1 vote
1 answer
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Mica Insulator for TO-220 Grounded Heat Sink

If I have a three terminal TO-220 voltage regulator where the center terminal and heat sink are connected ground terminals, is there any reason not to mount the heat sink directly to an aluminum ...
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3 answers
82 views

Is the melting point of pure indium too low to safely use to solder together a custom copper heatsink to be used ontop of motherboard mosfets?

Is the melting point of pure indium too low to safely use Indium to solder together a custom copper heatsink that will then be used ontop a motherboard mosfet? In other words, can the mosfets get hot ...
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2 answers
127 views

Heat sink sizing for LDMOS

There are many heatsink calculation Q&A's on SE that I've looked through. One very reasonable answer tells me that I can calculate heatsink C/W as follows: $$\frac{T_j - T_a}{P_d} - R_{JC} = R_{...
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3 answers
121 views

How to calculate if flyback diode needs heatsink?

I'm designing a circuit for automotive use, where I control various kinds of inductive loads (motors, solenoids, etc) up to 20A (Máx). In the design i'm looking into using 2 SMD N channel MOSFET in ...
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1 vote
1 answer
70 views

How can I reduce the power dissipated across this MOSFET without affecting avalanche?

previous and very relevant question here. I want to reduce or remove entirely the heatsink that is attached to my switching MOSFET. It heats up due to the back-EMF generated by the large inductor that ...
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  • 561
1 vote
3 answers
332 views

Can you connect two lm317's either in series or parallel to help spread out heat?

I am designing an adjustable voltage regulator. The regulator will have be able to swith between max Vout of 9V, 12V, 15V and 18V and will have a variable resistor that can adjust the voltage from 1....
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  • 77
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2 answers
321 views

LM338 gets very hot

I am trying make a variable voltage supply using part of this circuit: Instead of a transformer and a rectifier, I am using a solar panel, which gives 37 V (open circuit) and about 30 V with a load. ...
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3 votes
1 answer
55 views

Thermal circuit for shared heatsink

I am following this video from EEV blog where he talks about calculating heatsinks and I noticed that he does not talk about multiple components sharing a single heatsink. I have lurked around the ...
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1 vote
1 answer
161 views

DC solenoid overheat protection

I got 40 DC solenoids (12 V, 2 A) and each solenoid may be turned on for max. 5 seconds every couple of minutes or even more. Does this implementation require that an overheat protection should be ...
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0 answers
48 views

Peltier cooling calculation - Help ! :)

I have gone through many of online blogs and websites for guidelines about selecting Peltiers but somehow I am still lost in the middle. I am still missing major numbers to be able to select which ...
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Heatsink calculation for a MOSFET in active mode

Actually I am working on a project to create an electronic load for power supplies, batteries... testing. The circuit is already designed but I am working now in the heat disipation of the mosfet in ...
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0 votes
1 answer
31 views

is connecting high end high power leds in series feasible and are there light quality or other issues

i'm building high power high CRI cine lighting mostly to illuminate softboxes and have chosen Cree XLamp CMT2850 LED 1400mA 36V (Fidelity 95plus CRI). I plan to build about 12 units for the studio. I ...
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