Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [isolation]

Allowing for the flow of power or information without shared electrical nodes

Electrical isolation (also called galvanic isolation) can be achieved by transforming electrical energy into another form. These include magnetic fields (transformers), light (optocouplers and fiber-optics), mechanical (shaft-coupled motors), and vibrational (speakers/microphones).

664 questions
31
votes
4 answers

Why are the high voltage overhead power lines with the same potential being isolated?

Photo #1 Photo #2 Photo #3 - A zoom of Photo #1 Photo #4 - A zoom of Photo #2 I shot these photos while travelling in a highway. In each line-group has three separate lines. I think that the three lines in each group carry the same electrical…
hkBattousai
  • 13,913
  • 31
  • 114
  • 190
29
votes
5 answers

Why is it important for mains power supplies to be isolated?

In all the computer power supplies and other power supplies I've taken apart, I've noticed they are fully isolated from the mains. Galvanic isolation through transformers, and often optical isolation for feedback. There is usually a very visible gap…
Thomas O
  • 31,546
  • 57
  • 182
  • 320
18
votes
4 answers

Cellphone charger has no transformer?

I opened up a really tiny mobile phone charger I have, to see how it is designed. The entire "charger" is integrated into a small 2-pin mains plug, 1 x 1.25 x 0.5 inch, that has an USB socket for the phone's USB charging cable. I could not find…
Seemingly So
  • 592
  • 1
  • 4
  • 14
17
votes
4 answers

I ripped the lead off this film capacitor by mistake - is it beyond repair?

As the title says, I accidentally ripped the lead off this film capacitor. It was the only one I had - am I out of luck, or can this be soldered back on? I've provided photos, including one under my microscope of the damaged area. This appears to be…
riptusk331
  • 314
  • 2
  • 8
17
votes
4 answers

Is this a safe way to measure mains power on an oscilloscope?

I wanted to use my cheap battery powered single-channel oscilloscope or my Rigol 1054Z to see the 120V AC mains signal in my house. No particular reason, just curious. I at least knew enough to not just blindly stick the probe in the wall socket so…
Brad M
  • 181
  • 1
  • 4
17
votes
1 answer

Isolated DC/DC Converter - Purpose of Capactor connecting two GNDs?

I've been looking at board mount isolated DC/DC converters to use in an application. I found this rather reasonably priced for my needs. Here is what I'm confused about, what is C103 doing here? Isn't it breaking the isolation? Or, is it because…
Saad
  • 5,319
  • 12
  • 60
  • 93
15
votes
2 answers

What values of resistor and capacitor to use for AVR reset pin isolation?

Background... I'm a newbie to AVR applications. I recently built two ATTINY13-based circuits (glorified LED blinkers) which worked correctly (independently) on the breadboard. When I combined them on a solder perfboard with a shared power supply,…
JYelton
  • 32,302
  • 33
  • 134
  • 249
14
votes
2 answers

Why does this isolation transformer have another transformer in it?

The isolation transformer I'm looking at: http://www.mouser.com/ds/2/336/HX1188NL-515471.pdf My question is why is it there? Is it not enough to have just the transformer on the left?
VanGo
  • 1,167
  • 1
  • 14
  • 31
12
votes
2 answers

Why AC points on PCB are separated by a hole

I want to find out why, in professional PCB's, they separate between the AC (220 VAC) points on the PCB with a hole in the PCB: Is it for more isolation between the AC lines? Is leaving a distance between the two AC input points on the PCB not…
mina_g
  • 1,355
  • 4
  • 18
  • 21
12
votes
3 answers

What is this white trace on this PCB?

I saw this image where the "white trace" is (I think) trying to separate high current 220VAC. Do you know what is that white paint made of? EDIT: Image source: Shelly Facebook Page While trying to find an answer to this, I looked (without much…
Carlos Garcia
  • 1,116
  • 1
  • 7
  • 25
12
votes
4 answers

Is galvanic isolation of Hi-speed USB impossible?

I have a USB isolator which provides galvanic isolation of a USB device from my PC, but only works for low speed and full speed USB. I can't find any alternative electric isolators which do provide Hi-speed connection; USB fiber extenders, however,…
Daan
  • 329
  • 1
  • 2
  • 8
11
votes
2 answers

Why are there so few oscilloscopes with dedicated isolated channels?

Background I am a junior engineer who works with testing and designing inverters for motors. I have been looking at a new oscilloscope since the one I had gave up. There are a lot of Tektronix TPS2024b being used since it has dedicated isolated…
MisterB
  • 113
  • 1
  • 7
11
votes
1 answer

Why do the TO-220 79xx series voltage regulators conduct the input voltage to their heat sink?

I find it somewhat dangerous to connect a large heat sink on 79xx series voltage regulators. Because, they transfer all the negative input voltage to the heat sink. Why just they didn't make the 2nd pin of 79xx series GND, as it is done for the…
hkBattousai
  • 13,913
  • 31
  • 114
  • 190
10
votes
2 answers

Isolation Transformer

When a function generator is used to power a full wave rectifier an oscilloscope will not show the correct output due to a shared ground. A half wave is displayed because one of the diodes is 'shorted'. All of my research points me to the addition…
atomSmasher
  • 708
  • 1
  • 11
  • 23
10
votes
5 answers

Analog isolation vs Digital Isolation

I am designing an ADC front-end circuit that will accept a 230 Vrms mains connection. My goal is to measure the RMS voltage of the mains. Though not really necessary, I think it would make sense to galvanically isolate the mains voltage from the…
macdonaldtomw
  • 1,420
  • 17
  • 32
1
2 3
…
44 45