Eddy Currents

jsa_ind · 13th May 2006, 07:29 PM

Is it true that having metal parts near electronic circuits would generate Eddy Currents ?

If so would Eddy Currents be generated when a Aluminum Heat Sink is used on a Power Transistor block ?

Please help me understand this concept !

Thanks,

jsa_ind

MikeB · 13th May 2006, 09:54 PM

Eddy currents are generated by magnetic induction inside metal, you need a changing or pulsating magnetic field to get them. As in a normal amplifier magnetic fields are minimal the answer to your 2nd question is NO.
You might get eddy currents if metal is close to the output inductor, but still they are too small to have any effect.

Mike

ilimzn · 13th May 2006, 11:52 PM

...at and well above audio frequencies. Eddy currents can be a problem elsewhere (for instance when air core or air gapped inductors are used - like in class D output filters - or at (V)HF) but normally in an audio amp, it's not a problem. One exception is induction from a stray field of a transformer in proximity with the circuit, but _eddy_ surrents would be far less of a problem then actual induced voltages across various circuit parts.

MikeB · 14th May 2006, 10:05 AM

Maybe a bit OT, but very interesting to see how destructive eddy curents can be...

http://members.tripod.com/extreme_skier/cancrusher/

Look at the Joule numbers used !

Mike

13th May 2006, 07:29 PM	#1
jsa_ind diyAudio Member Join Date: May 2005 Location: Orlando	Eddy Currents Is it true that having metal parts near electronic circuits would generate Eddy Currents ? If so would Eddy Currents be generated when a Aluminum Heat Sink is used on a Power Transistor block ? Please help me understand this concept ! Thanks, jsa_ind

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13th May 2006, 09:54 PM	#2
MikeB diyAudio Member Join Date: Apr 2004 Location: Gütersloh	Eddy currents are generated by magnetic induction inside metal, you need a changing or pulsating magnetic field to get them. As in a normal amplifier magnetic fields are minimal the answer to your 2nd question is NO. You might get eddy currents if metal is close to the output inductor, but still they are too small to have any effect. Mike

13th May 2006, 11:52 PM	#3
ilimzn diyAudio Member Join Date: Feb 2005 Location: Zagreb	...at and well above audio frequencies. Eddy currents can be a problem elsewhere (for instance when air core or air gapped inductors are used - like in class D output filters - or at (V)HF) but normally in an audio amp, it's not a problem. One exception is induction from a stray field of a transformer in proximity with the circuit, but _eddy_ surrents would be far less of a problem then actual induced voltages across various circuit parts.

14th May 2006, 10:05 AM	#4
MikeB diyAudio Member Join Date: Apr 2004 Location: Gütersloh	Maybe a bit OT, but very interesting to see how destructive eddy curents can be... http://members.tripod.com/extreme_skier/cancrusher/ Look at the Joule numbers used ! Mike

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