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Old 31st March 2013, 11:47 AM   #31
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I know, I guess the bigger question is about whether or not there are two parts. My understanding was, that the R065 was depletion mode, but as you both pointed, traditionally the E in SJEP, stands for enhancement. I was aware of this, just expecting the other. I find no datasheet on the SJEP065R55. Either way, if you look at the datasheet for the two, you see very similar characteristics. My curves for the R085 look like Mike's, but i am unable to go out as far as he does, due to tracer limitation. IF you are thinking to play with them, I have 4 R085 I can send with your boards. I nhave plans for them, but based on current work load, i want be getting to them any time soon. I thought a F1J using them as LTP seemed interesting. THats what I was going to try as well as single stage ACA.
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Old 31st March 2013, 11:54 AM   #32
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Was it |1V| gate bias stepping on the chart you posted by the way? Or less, 1/4 maybe?
I found my notes on that one. Those were .1V steps starting with -4.4V.
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Old 31st March 2013, 11:55 AM   #33
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some of "my" ( servo function never really fully tested ) Semisouth Donuts are also possible ........ in fact - perfect bed for testing , just because you can throw any of usual suspects in , without even need for rebiasing
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Old 31st March 2013, 12:01 PM   #34
Salas is offline Salas  Greece
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Buzz thanks, but I have a couple already maybe for more than a year now.
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Old 31st March 2013, 12:02 PM   #35
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What kind of Donut would one need, spec wise? Gotta stare at thing for a while. So the BJT LTP watches the output and manipulates CS for the SS LTP
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Old 31st March 2013, 12:04 PM   #36
Salas is offline Salas  Greece
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Originally Posted by Michael Rothacher View Post
I found my notes on that one. Those were .1V steps starting with -4.4V.
Thanks Michael. Looking forward for when you will be tracing the CREE. Which is a normally available new and economic part.
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Old 31st March 2013, 12:24 PM   #37
Zen Mod is offline Zen Mod  Serbia
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What kind of Donut would one need, spec wise? Gotta stare at thing for a while. So the BJT LTP watches the output and manipulates CS for the SS LTP
huh

it's sometimes ( frankly - mostly ) hard to keep track with my self , so it's hard to know what I tried/tested , what I just drew , and what I'm just dreaming

you don't need servo , at least not for testing ; you can keep simple biasing mech. implemented in Magura's Donuts ( so , no servo ) and later build from that , if needed

I never had opportunity to polish that sch drawn for Magura , tempco wise , just because his amps are so ooking huge , having thermal capacity of nearest Lake to Jaccolina

if you insist going that way , I can sim it and be sure for 98%

I presume any 500VA ( and higher ) toroid is good for start , using 2x110V secondaries , to have split load choke

then - varying input signal ( or altering feedback or degeneration) of one side you can alter THD spectra

edit :

aha , tnx , yes , I'm ooking Genius
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Last edited by Zen Mod; 31st March 2013 at 12:32 PM.
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Old 31st March 2013, 03:26 PM   #38
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Mr. dB,
The piezo is attached to a combination interface/cross-over /attenuator to form an integral self-contained super-tweeter unit.
Piezo drivers as super-tweeters is a sadly neglected topic of experimentation and consequently a rich vein to mine IMHO.
Hiraga did devote a couple of pages to piezos in 'Les Haut-parleur' with special mention of the Motorola unit.
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Old 31st March 2013, 07:39 PM   #39
stajo is online now stajo  Sweden
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if you insist going that way , I can sim it and be sure for 98%

I presume any 500VA ( and higher ) toroid is good for start , using 2x110V secondaries , to have split load choke
I insist. My irons are in the making
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Old 31st March 2013, 09:18 PM   #40
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Ooh!
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