Why don't electronics care if it's DC or AC current?

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Discussion Overview

The discussion centers around the differences between AC (alternating current) and DC (direct current) in electronics, particularly why certain devices function with both types of current and the implications for devices like light bulbs and computers. It explores theoretical and practical aspects of power supply conversion and the behavior of electronic components in relation to AC and DC.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that AC is economically advantageous for transportation and production of electrical energy, while questioning why electronics do not seem to turn on and off with the alternating nature of current.
  • It is mentioned that incandescent lights flicker at a frequency that is imperceptible to the human eye, which may contribute to the perception that they do not turn off.
  • One participant clarifies that power supplies convert AC to DC to provide a steady flow of current for electronics, indicating that the distinction between AC and DC does matter for functionality.
  • Another participant points out that certain components, like transformers and capacitors, behave differently with AC and DC, highlighting that some electronics do care about the type of current.
  • Questions arise regarding the output of computer power supplies and the safety of modifying them for alternative uses, such as charging capacitors.
  • Concerns are raised about the dangers of modifying power supplies due to high voltages and the recommendation to use safer alternatives for experimentation is provided.

Areas of Agreement / Disagreement

Participants express differing views on the implications of AC versus DC in electronics. While some agree that the type of current matters for certain components, others question the extent to which electronics "care" about the current type, leading to an unresolved discussion.

Contextual Notes

The discussion includes assumptions about the behavior of light bulbs and the operation of power supplies, as well as safety considerations that are not fully explored. There is also a lack of consensus on the broader implications of AC versus DC in various electronic applications.

calvinjhfeng
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I understand AC is economic for transportation and easy to produce from converting mechanical energy into electrical energy.

However, why don't electronics turn on and off because of this alternating nature of the current? For light bulb, maybe it does turn on and off and our eyes don't have fast enough *shutter speed* to capture the off moment so we are just seeing the average brightness of the light bulb.

But what about computers? They did something to the battery so it doesn't turn off when current reaches its 0 point?
 
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An incandescent light turns on and off 120 times a second (the polarity reverses at double the operating frequency. The filiment doesn't have time to cool off so we don't "see" the flicker.
In electronics (like your computer) the power supply converts the AC to DC so the electronics can do their job in an uninterupted flow.
 
This is puzzling. What makes you think electronics "don't care"?

I have a power adapter that converts the household AC into a 12V DC for one of my "electronics". This is an obvious example that it DOES matter if it is AC or DC for some components!

Zz.
 
Some electronics do care about AC or DC.

Transformers only work on AC power.

Capacitors block DC but will allow an AC current to pass (also the frequency of the AC is important as a higher frequency passes through more easily)
 
Ahh I see, thank you.

So are all computer power units have DC output? Can I modify the connection so I can use it as a power source to let's say charge a capacitor?
 
calvinjhfeng said:
Ahh I see, thank you.

So are all computer power units have DC output? Can I modify the connection so I can use it as a power source to let's say charge a capacitor?

I wouldn't recommend modifying the power supply in your pc as it could be very dangerous due to the voltages involved and the fact you are using it for a purpose that it obvoiusly was never intended.

If you wish to experiment with some basic electronic components you would be better off getting a cheap lab power supply as these will provide a safe source of power and are fused in case of any faults that may occur.

If you can't get a lab power supply then you could use a battery snap to connect a 9V PP3 battery and that should be adequate for most small electronics circuits.
 

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