Donut a' la overkill

[Magura]

So, here is a little something.This project has been ongoing for 8 years by now, and for some strange reason it's about to come to an end.The electronic part is the result of a collaboration between Zen Mod and yours truly.The box is the result of my need to escape the reality from time to time First a schematic:Magura

[Zen Mod]

just keep them coming

[Magura]

One of the latest steps: A machined PCB. Initial layout by Spavleski, trimmed to snuff by yours truly.Magura

[Magura]

Which has been populated by now.Some of the components will look familiar to the members from behind the ex-iron curtain.Magura

[Sipi]

Greetings Magura,please tell what's the voltage on cascode MOSFETs' drains, and what's the "BIG DONUT" choke ?If those 47R/1W resistors see voltage close to +20V there will be a lot of smoke, but who cares, it's smoke induced circuit anyway

[Zen Mod]

Greetings Magura,please tell what's the voltage on cascode MOSFETs' drains, and what's the "BIG DONUT" choke ?If those 47R/1W resistors see voltage close to +20V there will be a lot of smoke, but who cares, it's smoke induced circuit anyway

those 47R are there just for fun ...... intended for deflorating the amp , during first full throttle test

[Sipi]

those 47R are there just for fun ...... intended for deflorating the amp , during first full throttle test

To deflower it, first it has to resemble the flower - this one you can only debug

[Magura]

what's the "BIG DONUT" choke ?

The "big donut" is a 2 x 90mH air core choke. The "big" part of "big donut" , refers to its physical size. Approximately 350mm diameter, and 120mm tall. Some 20kg of copper Magura

[Sipi]

The "big donut" is a 2 x 90mH air core choke. The "big" part of "big donut" , refers to its physical size. Approximately 350mm diameter, and 120mm tall. Some 20kg of copper Magura

WOW ! You must have inherited a copper mine!Really impressive!I thought you'll use some toroid transformer's center taped secondary - this way, with air core inductor, it will hardly find a way to average DIYer's heart Nevertheless, keep up the good work and please keep us informed on progress!

[Magura]

WOW ! You must have inherited a copper mine!Really impressive!I thought you'll use some toroid transformer's center taped secondary - this way, with air core inductor, it will hardly find a way to average DIYer's heart Nevertheless, keep up the good work and please keep us informed on progress!

If only I had inherited a copper mine That would have made this a little less daunting to the bank account Actually, I am just an average DIY'er, but have spent a little more time than most are willing to. This construction is really not that much more expensive, than what you frequently see people build. I just have put the money where I thought it is important, and haven't spent them on silver capacitors and fancy wire.Magura

[Magura]

Here you can see one of the more fancy solutions. A shielded inductor, for the CLC filter.To make a shielded air-core inductor is not as simple as it may seem. It requires a balance of ferro-magnetic and non magnetic shielding material, to leave the inductance unchanged, and not get in trouble with saturation. This I got around, by making a "cup" of ferritic stainless steel, and a base that doubles as a heat-sink, of copper.To get the heat transfered to the copper base, I have potted the whole thing.Magura

[Sipi]

...Actually, I am just an average DIY'er, but have spent a little more time than most are willing to...

Absolutely true, but then again, your dedication to detail, especially in mechanical domain, is well known I would rather unload the truck of bricks than wind a 90 mH air core coil - don't know why but I'm really reluctant when it comes to coils (maybe because I worked many years with short-wave transmitters) and that makes your work even more impressive in my eyes. Your fancy coils I won't even comment

[Zen Mod]

.....I would rather unload the truck of bricks than wind a 90 mH air core coil - ....

it's easy when you are winding them on lathe (or milling gadget) , not sissy winding machine and - especially - when your woman is , in fact , winding those coils ..... while you are sitting

[Sipi]

it's easy when you are winding them on lathe (or milling gadget) , not sissy winding machine and - especially - when your woman is , in fact , winding those coils ..... while you are sitting

That's the way to do it: - You want equal rights honey? - Good, how about some thick wire coils?

[Magura]

I would rather unload the truck of bricks than wind a 90 mH air core coil - don't know why but I'm really reluctant when it comes to coils (maybe because I worked many years with short-wave transmitters) and that makes your work even more impressive in my eyes. Your fancy coils I won't even comment

If I had the choice, I'd too take unloading a truck, rather than winding those coils, any day Nasty type of work if you ask me.Then you should also know how nice coils are (once made that is), I for one have had some very nice experiences with inductors, and as the copper price has gone down a bit, they're not even all that expensive anymore.As Zen Mod says, I used a lathe for winding them, but to tell you the truth, it didn't make much of a difference to how sore you get -And no, we don't have that much equal rights here, that I get inductors served for a hug and a kiss Magura

[Magura]

it's easy when you are winding them on lathe (or milling gadget) , not sissy winding machine

Difference mainly being, that a lathe does not hit the max weight limit Magura

[Zen Mod]

.....

in any case - send my kisses to your avatar

[Magura]

in any case - send my kisses to your avatar

Will do Here is the finished shielded inductor. 5mH, good for 20A.Magura

[Zen Mod]

Will do Here is the finished shielded inductor. 5mH, good for 20A.Magura

when finished - I wanna all these pics , each one no smaller than 1MB

[Magura]

when finished - I wanna all these pics , each one no smaller than 1MB

I'll make a folder, and save the pics then. It's also getting more interesting now, as it's not just a bunch of funny looking parts. Now it's actually possible to tell they have a purpose (sort of).Magura

[Magura]

To be able to control the orientation of the heat-sinks, I had to make precision bolts for mounting them. To make it look like I had a bit of integrity, I chose to make the nuts for this as well.Making 1 is ok Magura

[Magura]

Making 50 is somewhat less fun Magura