Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [dissipation]

30 questions
17
votes
4 answers

125 mW resistor subjected to 600 mW dissipation in professional safety system

The schematic below is the input circuit of a signalling PCB, which we buy from one of our suppliers of fire detection systems. Said PCB has to be built into a so called geographic evacuation panel which allows firemen to see in which zone of a…
Bart
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14
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How does static dissipative foam work?

I am planning to build a grip-release sensor using the foam. I'm pretty interested in the way it works. Does the resistance in circuit increase or decrease when force is applied onto it? And this will be proportional to the force in what manner? I…
Karl Stark
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4 answers

Book Suggestion - How to calculate the power dissipation of a BJT

I did a exam that asked for "power dissipation" of a given BJT circuit. The question was simple but my professor considered my calculation of dissipated power wrong, because my answer was \$P = V_{CE} \cdot I_C + V_{BE} \cdot I_B\$. But he told me…
Luis
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Technical explanation desired: are TVS safe for continuous dissipation? Why/why not?

In answers such as this one, https://electronics.stackexchange.com/a/647135/311631 I've seen suggestions that TVS diodes are not "reliable" under repetitive or continuous operation, such as a Zener diode might be used. (Assume the poorer tolerance…
Tim Williams
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7
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How to estimate the required PCB surface area for SMD power resistors

I am migrating a design from through-hole parts to use as many SMT devices as possible. There are 7- 2 Watt power resistors in the current design. These are metal-oxide resistors that have crimped and formed leads so as to raise the body of the…
Dwayne Reid
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Does a transistor/FET dissipate more power with a freewheel diode?

My question is: Does the transistor dissipate more power because of the freewheel diode? Ifso, why? simulate this circuit – Schematic created using CircuitLab
Toon Van Eyck
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Heater - how to define power needed taking into account air thermal dissipation

My objective is to heat a liquid inside a bottle. I have a air gap of 2 cm between the bottle and the heating element (resistive layers). The heater and the bottle is surrounded by a bottle insulator, so the volume of air to heat is fixed. I did the…
Armand
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Thermal pads, their thickness and conductivity

I would like fo know how do thermal pads work, more specifically why does their thickness matter so much even more so than their actual conductivity numbers sometimes and how do I choose the proper thickness, or rather how do manufacturers choose it…
appwizcpl
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Calculation of Power Dissipation of Memory ICs and Microcontrollers

Can someone tell me how to calculate the power dissipation of digital ICs like Nand Flash, QSPI NOR Flash and Microcontrollers? For Microcontrollers, we can get the power dissipation for GPIO like, Vdd (Voltage domain) * Id (drive current). But what…
user220456
1
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0 answers

Energy dissipation in a circuit with only capacitors

Context: Consider a circuit with only two linear time invariant capacitors. If I charge one the capacitors and then throw a switch that closes the circuit, there will be some redistribution of charge. The capacitors are ideal and there is no…
AkaiShuichi
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Best practices for a phenolic spacer design to facilitate heat transfer?

I am making a hand held electronic device that includes a 0.8mm phenolic spacer/electronic insulator between the PCB and the inside/bottom of the case. This spacer is made from epoxy resin and is currently solid save for one 300mm hole. Since I want…
redeyedjim
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Power used by a PLC for communication

I am working on a PLC (Programmable Logic Controller) that receives input from four pressure sensors (4-20mA) and a proximity sensor. Two of the outputs actuate relays. The PLC communicates via Modbus protocol with an HMI (Human Machine Interface).…
ChrisFord
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Heat dissipation Aluminum PCB

I'm not sure how to calculate the following. I want to SMD solder either 3 LEDs or 6 LEDs to an aluminium core PCB. The LEDs in question are PK2N (datasheet) and, according to the datasheet, the Thermal resistance of Junction to Slug is 8 deg C /…
made2hack
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Calculate Power Dissipation of an IC

I am trying to calculate power dissipation of the IC for thermal analysis of the PCB. I have calculated the power consumption but not sure which current values to be considered for calculating power dissipation of particular IC. Power Consumption =…
user1890
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Determining which fuse to use and where to put it

I've been working in my thesis project which consist on a PID controler to mantain a certain temperature in a case. The heater module is made of two 40W-12V 3D printer resistors and one 15W-10 Ohm wirewound resistor. In addition to these, I have an…
Shupper
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