Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Most Popular

more tags
1500 questions
22
votes
3 answers

How do I create a permanent application from something prototyped with Arduino?

Part one of a three part series on transitioning from Arduino to a plain AVR microcontroller and minimum supporting components (part two, part three) I've built up a project on my Arduino Uno to control various aspects of my beer brewing system.…
Pete
22
votes
2 answers

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 think that the current flow will reduce over time…
quantum231
  • 11,218
  • 24
  • 99
  • 192
22
votes
14 answers

Why can't I power everything with a 9 V DC battery?

I am a student and have a very basic knowledge of volts, ampere, watts, charges, etc. My question is fairly simple: Why can't we use 9 V DC batteries to run everything in the world? Because it's DC, and we need AC to run appliances. Answer: Use an…
Waleed
  • 379
  • 1
  • 1
  • 7
22
votes
3 answers

Any published designs for time-of-flight laser distance measurement

Does anyone have any references/examples for detailed circuitry for time-of-flight laser distance measurements - schematics, appnotes etc.?
mikeselectricstuff
  • 10,655
  • 33
  • 34
22
votes
2 answers

Why do these LEDs have different brightnesses

I did a search for 0603 sized high brightness Kingbright LEDs on element14, results are here . Why is there such a range of luminous intensity, even within the same colour, despite forward voltage, forward current, size and viewing angle being the…
geometrikal
  • 4,921
  • 2
  • 23
  • 41
22
votes
8 answers

Single wire (no ground wire) long distance low frequency communication

In a cave we are currently exploring, there is a temporary siphon that sometimes blocks our way. I was thinking about monitoring it (pressure sensor or other level sensor at the siphon, transmitter via mobile phone outside the cave.) The problem is…
Sandro
  • 5,519
  • 6
  • 24
22
votes
7 answers

In PCBs, why is copper etched away instead of added?

I know that in virtually every case, PCBs start as a substrate with a layer of copper laminated on top, which is then etched away, leaving the traces. But why are the traces not added on an empty substrate instead? I am well aware that the etching…
David Cian
  • 747
  • 6
  • 18
22
votes
7 answers

Is it bad practice to parallel power connector contacts?

Say I'm looking for some power connectors for a design, the current requirements are quite high and although I could get a connector with contacts rated for the full current, they're so bulky that they're unattractive for my design. Smaller power…
VBwhatnow
  • 602
  • 5
  • 15
22
votes
3 answers

Microcontroller with both ethernet and radio onboard?

Does anyone know of any (reasonably low-cost) SoC which combines all of: Microcontroller (any architecture, at least 4KB RAM/8KB flash) Radio transceiver (433MHz - 915MHz or 2.4GHz) Ethernet MAC + PHY (For a wireless sensor application -…
Toby Jaffey
  • 28,796
  • 19
  • 96
  • 150
22
votes
3 answers

What does a two overlapping circles symbol mean in an electrical schematic/diagram?

In the datasheet for a A3503 Hall Effect Sensor, I saw a circuit diagram labeled 'Functional Block Diagram', and it shows a symbol I have not seen before. It's shown here between 3 - Output and 2 - Ground. What is this supposed to represent? The…
Ehryk
  • 1,141
  • 5
  • 16
  • 28
22
votes
4 answers

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 resistance (the highly conductive copper PCB paths, for…
Asker
  • 223
  • 2
  • 4
22
votes
6 answers

Why recommend tantalum over ceramic capacitor for voltage regulator?

The LM1117 voltage regulator datasheet recommends using tantalum capacitors on the input and output. What is the reason for this? What advantage does tantalum have over a ceramic capacitor? A 10μF tantalum capacitor costs about 21 cents, while a…
user31708
  • 843
  • 1
  • 9
  • 13
22
votes
3 answers

Soft core processors vs hard core processors

I am doing a study on FPGA interfacing with microprocessors such as ARM9. I found the concept of soft core processors and hard core processors in my study. May I know what is the comparison between these two types, the similarities and differences…
How Xing Quan
  • 321
  • 1
  • 2
  • 3
22
votes
5 answers

How to safely ground a switching power supply with floating outputs?

I just received a 120VAC to 5VDC (20A) switching power supply (the kind with a passively ventilated metal casing) for use with a microcontroller project I'm working on (driving long LED strips). I've wired up Line-Neutral-Ground correctly to a…
MartyMacGyver
  • 704
  • 1
  • 8
  • 19
22
votes
3 answers

Design a veroboard/stripboard layout from an Eagle schematic

So I have just finished learning the basics of Eagle (Lite) and I really like it. As I don't have the full kit to start home PCB etching yet (something I am looking into now) I would like a tool that could help me design a layout for a…
Mr. Hedgehog
  • 2,117
  • 4
  • 24
  • 30
1 2 3
…
99 100