Panasonic power resistor query

Stuart Easson · 16th February 2003, 04:32 AM

I'm hoping someone out there with a great memory or the right docs can help me. I have a large number of panasonic power resistors, part # ERF-10EJR68L, but no specs beyond their nominal value and wattage, (0.68ohms, 10w). Searching on the web did not reveal anything useful. They seem like reasonable devices, but I have no idea how they are constructed, ie wirewound versus metal film etc. They are rectangular, approx 2cm by 3cm,, perhaps 4mm deep, packaged in a white, ceramic cell. I have not yet whacked one to examine it's guts, but it may come down to that.

Thanks for any help

Stuart

AudioFreak · 16th February 2003, 04:53 AM

They are wirewound 5% or 10%.

Stuart Easson · 16th February 2003, 05:18 AM

Audiofreak, thanks for your help, do you happen to have a more comprehensive source for the rest of the specs? The tolerance though important is not critical as I plan on matching them in a bridge to get very tight tolerances. I was more wondering on whether they are 10w in free air or if there is an assumption about mounting. Plus I guess I'd sort of like to know what their intrinsic inductance is etc.

Stuart

AudioFreak · 16th February 2003, 05:21 AM

I believe that they are 10W in free air but I cant provide any more info than that sorry.

mrfeedback · 17th February 2003, 03:36 AM

I have cracked open flat ceramic emitter resistors.
The resistive element waz a flat zig-zag piece of resistance alloy, presumably to eliminate inductance.

Eric.

Stuart Easson · 17th February 2003, 05:26 AM

Anyone know about the issues with inductance in wirewound resistors? I can imagine there are many situations where a micro-henry or two would be a problem, but most audio amps use an inductor in the output to provide more weird load stability, so it seems unlikely this is a big problem in a degeneration resistor. Another issue I can perhaps believe in is with mutual inductive coupling between adjacent resistors, especially given the relatively high currents in the output stage. Presumably this problem, if it exists can be fixed by proper physical arrangement...

Your thoughts gentlemen

Stuart

16th February 2003, 04:32 AM	#1
Stuart Easson diyAudio Member Join Date: Oct 2002 Location: Santa Cruz, CA	Panasonic power resistor query I'm hoping someone out there with a great memory or the right docs can help me. I have a large number of panasonic power resistors, part # ERF-10EJR68L, but no specs beyond their nominal value and wattage, (0.68ohms, 10w). Searching on the web did not reveal anything useful. They seem like reasonable devices, but I have no idea how they are constructed, ie wirewound versus metal film etc. They are rectangular, approx 2cm by 3cm,, perhaps 4mm deep, packaged in a white, ceramic cell. I have not yet whacked one to examine it's guts, but it may come down to that. Thanks for any help Stuart

16th February 2003, 05:18 AM	#3
Stuart Easson diyAudio Member Join Date: Oct 2002 Location: Santa Cruz, CA	Any more info? Audiofreak, thanks for your help, do you happen to have a more comprehensive source for the rest of the specs? The tolerance though important is not critical as I plan on matching them in a bridge to get very tight tolerances. I was more wondering on whether they are 10w in free air or if there is an assumption about mounting. Plus I guess I'd sort of like to know what their intrinsic inductance is etc. Stuart

17th February 2003, 03:36 AM	#5
mrfeedback diyAudio Member Join Date: Feb 2002 Location: Perth, Australia.	I have cracked open flat ceramic emitter resistors. The resistive element waz a flat zig-zag piece of resistance alloy, presumably to eliminate inductance. Eric. __________________ I believe not to believe in any fixed belief system.

17th February 2003, 05:26 AM	#6
Stuart Easson diyAudio Member Join Date: Oct 2002 Location: Santa Cruz, CA	Another question... Anyone know about the issues with inductance in wirewound resistors? I can imagine there are many situations where a micro-henry or two would be a problem, but most audio amps use an inductor in the output to provide more weird load stability, so it seems unlikely this is a big problem in a degeneration resistor. Another issue I can perhaps believe in is with mutual inductive coupling between adjacent resistors, especially given the relatively high currents in the output stage. Presumably this problem, if it exists can be fixed by proper physical arrangement... Your thoughts gentlemen Stuart

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16th February 2003, 04:53 AM	#2
AudioFreak Warp Engineer On Holiday Join Date: Oct 2001 Location: Queensland, Australia	They are wirewound 5% or 10%.

16th February 2003, 05:21 AM	#4
AudioFreak Warp Engineer On Holiday Join Date: Oct 2001 Location: Queensland, Australia	I believe that they are 10W in free air but I cant provide any more info than that sorry.

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