SemiSouth Donuts

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I would wait for thanks until it works. :devilr:

He is using LtSpice after all. Has it programmed to whisper sweet nothings in his ear.

Buzzforb, ZM..... No hurry on the Netlist, here--I'm just starting to learn Spice (specifically LT Spice) here, too. I'm trying to figure out how to do netlist and/or schematic capture in LT Spice, as I type..... (I'm too old for all this "new technology" stuff.....!)

I'd like one eventually for the final ZM Fugly amp, whenever that might be!
 
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disclaimer - will check small details later tonight ; for now I'm sure 99% it will work as intended, last 1% pending my time

for both circs ( choke and CCS ) same apply - protective zeners for mosfet gates can't hurt ....... that and maybe few small details are grunschnabbel thing , so be aware

local caps decoupling , proper routing , proper grounding etc.

don't push it in B class :devilr:
 
Buzzforb, ZM..... No hurry on the Netlist, here--I'm just starting to learn Spice (specifically LT Spice) here, too. I'm trying to figure out how to do netlist and/or schematic capture in LT Spice, as I type..... (I'm too old for all this "new technology" stuff.....!)

I'd like one eventually for the final ZM Fugly amp, whenever that might be!

that one will probably stay unfinished , from moment they will bring me outa in a coffin :rofl:

I don't need them , I just like to dream ( and just sometimes make ) them ; time when I need to actually make it is past now , after some mileage .

now , just to learn how to make them then sell them , that will be interesting (place here attached smiley )

well - not actually these Papamp knock-offs ....... but some other ones ; even if that's harder and harder - he actually covered all types one is able to make , in simple and pure way

btw. easiest way to share files is just sharing *.asc files , and accompanying models

I'm learning LTS too , just scratched it , in fact
 

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I've tried using large toroids as loads for mosfets but ran into the problem where the mosfet's output Z shorts the toroids inductance below 100hz. How does this circuit get around that? For the most part choke loaded SS amps are only good from 100-a few Khz.

Tubes work because their plate resistance is hundreds of ohms. SS doesn't because thier Rds is very low.
 
physics is simple - you have voltage loss of 6db where Lz is same as Ri of part driving it

so - tubes demands much greater inductance to work with , while sand parts are demanding much lesser inductance

but , as current goes up , keeping resistive losses in choke at minimum is must

play a little with this files , scavenged from VT52.com
 

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Zen Mod,

Nice tools.

I used a 200VA Anvil toroid that has two 117V primaries and two 18V secondaries as a push pull output transformer in the source of a differential e-mosfet long tail pair with poor results.

I did this understanding the primary inductance would need to be a few henery. DCR was <1ohm.

What results are you guys seeing in bench tests?

It would be great to get this working. We could build very simple class a and high powered class b amplifiers.
 
I can't remember what L values Magura is having in his big Donut amps , but you can count on mH , not H

there is long history of choke loaded amps , from first day of audio amplification , so it's superfluous to count how many times concept is proven

however - all you need to know is in that xls files , even if calc is simple formula , so you really don't need them

as Fo (for -3db point ) use 20Hz and you'll see

btw. with Magura's ( or even my ) approach - 200VA Donut is good for preamp :clown: ....... but - demands of split choke are simpler , comparing to real OPT which is having primary and secondary side ........ completely different beasts

- me played with 800VA CU core - isolation xformer from some old German TV set and Senisouth R550s ; have prepared some 1KW EI isolation xformers , but with negligible Rdc , comparing to previous one ; though , Mithrandir pulled me back to SE area lately ....
 
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