The Amazing Fet Circlotron by Mike Rothacher - Page 18 - diyAudio
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Old 29th April 2011, 10:10 AM   #171
Gyuri is offline Gyuri  Hungary
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Quote:
Originally Posted by cnpope View Post
Gyuri: Well I suppose I did more or less copy the construction style I used for my OTL based on Tim Mellow's design:

Chris
Well, Chris, you're a true artist of DIY.
So much that I decided, I make an amplifier such as that you do.
(Maybe this is not just me at this place would have had to say.
Here now because I thought the OTL.)
However, if someone put his foot to Papaland, not an easy to release.
I present to you one of my Amplifiers:

So, this is my Quad ZV9!

I also recommend that you build this.
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Last edited by Gyuri; 29th April 2011 at 10:13 AM.
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Old 27th August 2011, 09:30 PM   #172
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Default Part choice..

Hi folks,

I read the article and the thread related to the circlotron and will give the build a try.

Is there any reason not to use wirewound resistors for the power resistors ?

Are the values of 100 Ohm and 0.47 Ohm (3 Watt each) critical for the design ? I am asking because I have some 0.56 and 0.82 in my drawer.

Anty reason not to go higher on the supply rails ? I would have some 24V secondaries on the shelf as well...

Cheers,

Max
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Old 27th August 2011, 10:07 PM   #173
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You'd be pressing your luck with 32 volt rails. Get 100 Ohm resistors. Wirewound is fine.
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Old 27th August 2011, 11:48 PM   #174
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The .56 is okay.
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Old 24th October 2011, 07:25 PM   #175
dnewman is offline dnewman  United States
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Default Circolotron build

A vanilla Amazing FET Circolotron build. JFETs are 2SJS109BLs and the MOSFETS are matched FQA19N20C pairs. The resistor pairs are also matched. I opted to inset the top panels inside of the boxes rather than secure them to the tops of the boxes. (The panels are one half inch narrower in width and height.) So far they sound nice. After a couple of weeks, I'll measure them.

Click the image to open in full size.Click the image to open in full size.

Michael, thanks much for all the hard work in putting this project together!

Dan
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Old 25th October 2011, 11:45 AM   #176
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Nice build, Dan. The potted transformers look good.
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Old 26th October 2011, 03:26 PM   #177
ichiban is offline ichiban  United States
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Default The All JFET Circlotron

Hi Michael, Is the JFET Circlotron build/article getting any closer. I bought some SIC JFETs last year and have been searching for something to build with them.
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Old 26th October 2011, 09:13 PM   #178
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Even if I finish it in November, you have to figure it probably wouldn't be published until after the new year.

Having said that, it's really not going to be much different from the original (or at least that's what I think right now).
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Old 27th October 2011, 08:13 PM   #179
qusp is offline qusp  Australia
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Quote:
Originally Posted by Michael Rothacher View Post
Nice build, Dan. The potted transformers look good.
thats what i thought initially too, but i'm thinking its just a regular transformer in a can, the outside looks metal.

for those impatient Michael has documented the R100 circ on his DIYA blog using these boards and it is indeed pretty much identical
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Old 27th October 2011, 08:24 PM   #180
dnewman is offline dnewman  United States
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Correct -- it's just a transformer in a can. A very heavy can. It's a 300 VA transformer from Antek with one of their well constructed cans. My only grip with the can was that it was supposedly powder coated. While that may be the case, it wasn't a very durable coating. While I had had it for about three weeks (and hence the coat was at least three weeks dried/cured/whatever), it would scratch just by my looking at it. So, I had to refinish both cans. However, I'd buy them again should I need/want them as they are very well built. And, I'm quite satisfied with the Antek transformers I've used.

Dan
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