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Electric arcs and spark gaps: Are they active or passive devices?

Synthfan

Nov 6, 2015
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Hi, guys, quick question for the more technically-minded among you. As a novice, being able to identify certain components as active or passive still eludes me. I know that tubes and semiconductors are considered active because they apparently "use electricity to control electricity" or because they require a power supply to operate. I know that resistors, capacitors, and inductors are considered passive.

So what about electric arcs and spark gaps? Is the discharge component in an antique spark-gap transmitter or a Tesla coil an active component? What if an LC circuit were to be placed across an electric arc in, say, a carbon lamp -- would the arc be considered an active component in that case?

Thanks for any help with this!
 

AnalogKid

Jun 10, 2015
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Passive. An active device uses energy from one source to control energy from another source. Not necessarily amplify it, although it almost always is the case that a low energy control signal can activate a solid stage switch controlling a much higher energy level, and this could be considered a form of non-linear amplification.

For a truly ambiguous device, look up a tunnel diode.

ak
 

duke37

Jan 9, 2011
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And an arc will generate a negative dynamic resistance, like a tunnel diode.:)
 

BobK

Jan 5, 2010
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How about a normal diode, active or passive?

I would call the spark gap active for the same reason I would call the tunnel diode active, it exhibits hysteretic behavior, meaning how it acts depends on the past.

Bob
 
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