John Curl's Blowtorch preamplifier part II

[bcarso]

Originally Posted by Kindhornman

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.

[Kindhornman]

Sounds like our friends over there on Balboa Blvd. to me.

[bcarso]

Originally Posted by Kindhornman

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

[simon7000]

Originally Posted by bcarso

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?

[scott wurcer]

Originally Posted by simon7000

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

[bcarso]

Originally Posted by simon7000

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.

[RNMarsh]

Originally Posted by scott wurcer

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

[scott wurcer]

Originally Posted by RNMarsh

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).

[RNMarsh]

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

[qusp]

Originally Posted by scott wurcer

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?