John Curl's Blowtorch preamplifier part II - Page 3578 - diyAudio
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Old 23rd February 2013, 12:51 AM   #35771
bcarso is offline bcarso  United States
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Quote:
Originally Posted by Kindhornman View Post
bcarso,
That is with the voicecoil in the magnetic field or external to the field?
It's a test fixture for measuring voice coil d.c.r. under heavy drive by extracting the voltage drop due to a probe current while a large a.c. signal is driving the loudspeaker under test. But as well the fixture will provide r.m.s. current and voltage and true power (average of instantaneous i * v) in the manner of a Valhalla-like meter.

So, yes, the voice coil as part of the assembled and magnetized loudspeaker driver.
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Old 23rd February 2013, 12:59 AM   #35772
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Sounds like our friends over there on Balboa Blvd. to me.

Last edited by Kindhornman; 23rd February 2013 at 01:01 AM.
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Old 23rd February 2013, 01:40 AM   #35773
bcarso is offline bcarso  United States
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Originally Posted by Kindhornman View Post
Sounds like our friends over there on Balboa Blvd. to me.
They may have some potential customers there (Mr. Button continues to ask after it), but my pseudoclient is Dr. Marshall Buck.

Brad
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Old 23rd February 2013, 03:47 AM   #35774
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Originally Posted by bcarso View Post
They may have some potential customers there (Mr. Button continues to ask after it), but my pseudoclient is Dr. Marshall Buck.

Brad
Doug is back at JBL?
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Old 23rd February 2013, 04:07 AM   #35775
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Scott
The 7905 family of regulators I believe first appeared in the 70's. Is anyone still using those older processes to make current parts?

Certainly no one is using 2" wafers, I don't think the starting material is available anymore (maybe for some very exotic devices). We got a quote today for some specialty JFET's for an experiment $290 @ 1-9 in die form
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Old 23rd February 2013, 05:50 AM   #35776
bcarso is offline bcarso  United States
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Doug is back at JBL?
That's my understanding Ed, although I heard it second-hand --- I don't know Doug very well. From what I have heard about working for the folk at One Infinite Loop, in, as Larry Heyl used to say, the Land Without Adverbs ("Think Different"), I could well understand that it may not have worked out.
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Old 23rd February 2013, 06:00 AM   #35777
RNMarsh is offline RNMarsh  United States
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Originally Posted by scott wurcer View Post
Certainly no one is using 2" wafers, I don't think the starting material is available anymore (maybe for some very exotic devices). We got a quote today for some specialty JFET's for an experiment $290 @ 1-9 in die form
No problem-o. Just sell some to the military - they have lots of money. Recoup costs in no time at all.

-RNM
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Old 23rd February 2013, 06:17 AM   #35778
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No problem-o. Just sell some to the military - they have lots of money. Recoup costs in no time at all.

-RNM
They're made for particle detectors and other physics experiments, but get real even a 4" wafer has 1000's. It's funny they have a 1000 piece price of $109. Another vendor simply offered us a whole wafer (which is no problem here).
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Old 23rd February 2013, 06:37 AM   #35779
RNMarsh is offline RNMarsh  United States
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Still no problem for the military... they have more money than God. Must be some phyics guys connected to DOD funding you could take to dinner.
LN cooled detectors, by any chance?


-RNM
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Old 23rd February 2013, 07:41 AM   #35780
qusp is offline qusp  Australia
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Originally Posted by scott wurcer View Post
Certainly no one is using 2" wafers, I don't think the starting material is available anymore (maybe for some very exotic devices). We got a quote today for some specialty JFET's for an experiment $290 @ 1-9 in die form
interfet?
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