allFET circlotron

[kees52]

The winder, it did need a other case because the wood I use first was not very strong, plywood is better.

busy with system for wire, needs to search if there is a windows version of winding program, i have a microcontroller version with display, but maybe with pc is more easy.

regards

 

[kees52]

I have two setups for the circlotron, one do better as the other. but both has low distortion, however the balanced version who can be on the circlotron supplys so we need not a extra one do not as well as the version with his own supply and the balanced version, (yes both a balanced, but I give it just a name for easy separation) has three adjust points like two idle and one offset.

I think I go made the version with extra supply, it is not such a problem to make extra 500 ma a 1 amp on.

regards

 

[kees52]

All oke with you X? design new things? the circlotron is not yet dead but nabure trouble and such is still a issue, but very soon the judge do help, and I can go on, possible I go move to a other place.

I have almost ready the winder, because I need a input transformer for the ciclotron to avoid as much as possible an electronics, I can use opamps, but do not if I can.

Coming winter, or when weather is changing I go hobby again.

regards

 

[UltimateX86]

Hi, do you have an idea for this one ?

http://www.diyaudio.com/forums/solid-state/193923-simple-symetrical-amplifier-419.html#post5516239

Thanks

 

[xrk971]

All oke with you X? design new things? the circlotron is not yet dead but nabure trouble and such is still a issue, but very soon the judge do help, and I can go on, possible I go move to a other place.

I have almost ready the winder, because I need a input transformer for the ciclotron to avoid as much as possible an electronics, I can use opamps, but do not if I can.

Coming winter, or when weather is changing I go hobby again.

regards

Hi Kees,
Sorry about your crazy neighbor - still aiming open door microwave ovens at you through the walls?

I had a recent basement flooding so the speaker lab and electronics bench were out of commission for a while for cleanup and repairs.

How is your circlotron - music playing yet?

Cheers,
X

 

[kees52]

Hi Kees,
Sorry about your crazy neighbor - still aiming open door microwave ovens at you through the walls?

I had a recent basement flooding so the speaker lab and electronics bench were out of commission for a while for cleanup and repairs.

How is your circlotron - music playing yet?

Cheers,
X

Hi X

I am busy with some things around the house, because I need to go to judge because crazy nabure has complain about the woodstove, first it was the oldtimer volvo, now it is the stove, I have a very clean version and I do use it for over 9 years, but seek trouble every time again, en not a fight but just complain by owner hous or city hall, causing trouble like police who coming in mine house, while this nabure is sentenced for acuse me that I did sexual misuse children, who has as consequence that I did be treatened.

That is Holland, 22 august I need to go to judge, mine advocate do the work now, I do win becuase there are no rules about woodstoves and excaust, only savety, and that is oke.

YouTube

Oke, I am the strongest, because nobody do try to fight with me, I have a past of street fighter, that was because I had a big disco in that time, getting trained give much more rest when do that work. But it does give stress and that do work against mine drive to build things.

I am also busy with multilevel class D amps, I have a fase shifted version that has a -110 dB distortion level with 12 amps output full bridge, it does double the carrier from 400 to 800 Khz.

Now back to the circlotron.

I have done one who do have low distortion, the problem is the allfet, because of the capacitances it give troube sometimes, use low capacitance fets is the way. see picture of that and the winder for the input transformer, on ebay I did get the transformer iitself with audio friendly core.

regards

 

[kees52]

I have here the class D.

So low distortion and doubling carrier. But afcourse it is sim, not real yet.

Winter comes so much time to hobby behind the stove.

Maybe I can even go into a castle to live, as a security measure for the owner to prevent tear down of building and to safequard, castel is from year 1200 or so, and no nabures in the woods, but is big and protected, so I have tho think good about it. and or if it is livable, it is a cultural heritage and I may not change, I have to live as a night there with sword and all, and visit nabure later...

regards

 

[kees52]

Hi X

I have a question, how do you like the case for the hybrid? maybe also nice for the circlotron.

Need to find the heatsinks somewhere, because of heavy weight it needs to order locally.

Do you still experiment with horns? I did has idea to reopen it, because winter is coming and have much of time then, ignoring the nabure afcourse and make some mony with al this rich people outside there is market for high end stuff, onlly need a good name as always.

regards

 

[xrk971]

Nice case! I like using computer CPU coolers for heatsinks nowadays. They are cheap, compact and lightweight. With a minimal speed PWM fan controller, they are also silent. You can find used ones from dead PC's for $5 to $12. They will pull 100w load no problem with maybe 15C to 20C rise in temp.

You can get ideas in Alpha thread.

I have not made a new horn speaker in a while. I still think that horns sound the best though.

 

[kees52]

Nice case! I like using computer CPU coolers for heatsinks nowadays. They are cheap, compact and lightweight. With a minimal speed PWM fan controller, they are also silent. You can find used ones from dead PC's for $5 to $12. They will pull 100w load no problem with maybe 15C to 20C rise in temp.

You can get ideas in Alpha thread.

I have not made a new horn speaker in a while. I still think that horns sound the best though.

Hi X

I was some busy with a way to get a setup for the bias voltage, I can do change it for a better way with a using a current source, I can use a input transformer or two opamps, I use then cmos versions because it is a allfet you now, no place for bjt. the OPA 365 works fine, I can use the double opamp version better for spare place on pcb.

I get pretty low HD. on 5 amps output peak peak.

Need to design and optimize the bias circuit, so temp runaway out do not happen. only with the verticals, this is lateral output stage.

Square wave is 20 Khz, but I think overshoot is best to remove around 10 Khz, making amp bandwith some smaller, I think a fast high slewrate amp do not sound automatically good, I do all needed to prevent overshoots on squares, on 20 Khz some little rounded corners are best making the amp more relaxed in sound reporduction.

regards

 

[kees52]

Nice case! I like using computer CPU coolers for heatsinks nowadays. They are cheap, compact and lightweight. With a minimal speed PWM fan controller, they are also silent. You can find used ones from dead PC's for $5 to $12. They will pull 100w load no problem with maybe 15C to 20C rise in temp.

You can get ideas in Alpha thread.

I have not made a new horn speaker in a while. I still think that horns sound the best though.

The future of the pc are changing, and I think such a nice big heatsink do give the amp a better look, more durable.

But in near future class D will get the boss, als I did already sim some idea,s even multilevel class D, did get pretty low -100dB distortions also, using superfast components
are the rule, and good precision comparators.

regards

 

[kees52]

A question about the Vbe multiplier, to get some good correction against runaway, I have two options, can somebody look and advise what I have to do best, the first do infloence the vas while the other do less harm, and also do adjust better.

The Vbe needs inverted, as the resistance go lower when heat a transistor I get even higher current, that helps the runaway, so I need to use Q1 in stead of the mje Q2? I can use a second mje in stead of to92 to get more easy fit on the heatsink.

I have use both in sim, but have to build a small part of the amp to test it.

I have also a version with laterals, these do work fine without any vbe.

regards

 

[kees52]

It is quit here!

I have build up a test circuit for the idle current vbe multiplyer who is now on a other spot in schematic, on the power output side and not in driver circuit anymore, I think it is better because it does work already right from the sim test but maybe someone else thinks otherwise and do I miss things..

Oke, it over compensates, what to do best to correct that, maybe a mosfet as temp sensor because these match more with output mosfets.

The test cicuit do now settle itselfs on 170 mA coming from 470 mA when cold. But think with extra heat when play music loud it do get to low.

I like to hear ideas of changing things.

regards

 

[kees52]

here a movie to see it working.

YouTube

 

[kees52]

Did change the heatsink for a better one, the Vbe multiplier do some overcompensation, but not that much, it keeps now around 250 mA.

This kind of using the Vbe do work nicely in a circlotron, and so it als compensates the driver section of the power mosfets also.

regards

regards

 

[bwaslo]

Hi Kees,
Saw your schematic over on the Vbe Thermal Coupling thread. Was just curious whether you ever tried any of the depletion mosfets (like DN2540) as input devices in your model or circuit? I had very good results running them as cascoded inputs in a non-global-feedback circuit I was playing with a few years ago.

 

[kees52]

Hi Kees,
Saw your schematic over on the Vbe Thermal Coupling thread. Was just curious whether you ever tried any of the depletion mosfets (like DN2540) as input devices in your model or circuit? I had very good results running them as cascoded inputs in a non-global-feedback circuit I was playing with a few years ago.

Hi bwaslo

The idea is good, I think you do metion also the difficulti buying Jfets?, I have good results also with 2n54 series jfets who there are enough of them.

But I can afcourse always try your idea in a sim, so I let you now what happens.

regards

 

[kees52]

Have you still schematic of it? because mine models do not work here.

 

[bwaslo]

kees,

Not sure what you need, so attached is an LTSPICE file for the amp that uses it, the line from standard.mos for the DN2540, and a zip of my entire standard.mos file. Accuracy has been pretty good, except for the device capacitances. The model doesn't include nonlinearities of capacitances vs voltage -- which are pretty significant for this device, but cascoding pretty well takes care of them.

The part in the schematic is set up in a pretty much souped-up configuration, with Q4 and Q1 making a linearized cascode and Q2 set up with the DN2540 to make a hybrid Sziklai pair. But if you delete Q1 and Q2, short R14, open R31 and connect R21 to Q4's base, it will still work as a more basic cascode.

I imagine that much of the good result I have with DN2540 just comes from its high transconductance, but it's still worth a try in your circuit. The Sziklai boost doesn't hurt, either.

(The open collector BC546 NPN devices, by the way, are just being used as low leakage protection diodes).

 

[bwaslo]

I didn't really have trouble getting jfets, but got better results with the N-depletion MOSFETS (under condition of using only local feedback, which was more or less just an exercise)