some filament choke possibilities.

Design and use of Chokes for PS, anode and filament use.
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dave slagle
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some filament choke possibilities.

Post by dave slagle »

here are some plots of various possibilities for filament / Offset winding load chokes. They are wound on 2 mil thick steel C-cores (originally intended for use up to 10Khz)

The dcr and the circular mils will tell you the maximum current you can drag through them, I would use 500 circ mils per amp of current as a conservative value, 333cm/A as the edge, and 250cm/a in a pinch. They start getting real warm if you go beyond that :-)

The plots should give a good starting point and then the gap can be tweeked in circuit to get the best results.

Ps... jj, the 75T version should go out to 13A with the 10mhy gap, and will easily get there with the 7mhy gap.

dave
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JeffreyJ
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Signal Transformer link

Post by JeffreyJ »

I know that these aren't designed as high bandwidth, but it appears that they are back online.. and all the Signals I have owned over the years are first rate.. run cool.. finished industrial, but properly.. meet spec, etc...

link: http://www.belfuse.com/Data/DBObject/signalcatalog.pdf and scroll down to page 27...

they have single winding and dual winding chokes.. the one that sticks out like a sore thumb for 75tl's is the dual winding 6A/12A that is 0.15/0.38 Ohms and 12/3 mHy... I'm gonna guess that it is about $35.. the 6 lb. CH-6, which is a 40mHy, 6A filament choke is $40.. the dual winding unit above is only 4.5lbs...

Peace,
Me
JeffreyJ
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filament choke mini-update...

Post by JeffreyJ »

I finally have the 75tl filament supply up and running without the digital switching supply...

the old supply was digital switcher + > Hammond 2.5mH choke > parallel filaments > hammond choke > digital switcher -... the sound in this congfiguration was quite good.. the fan noise was driving me nuts, though... apparently it is somehow automated... so even though I dropped the voltage feeding it, when the unit's temp rises, the fan kicks up... :(

new supply was Signal power Tx > Schottky > cap > choke > cap > choke > cap > filaments > back to center tap...

then I moved the second choke to the ground leg because the sound was "plasticky" in the mids... and it wasn't really much better...

then I used Dave's 14A (amorphous steel?) filament chokes as a last element between the cap and fils.. I didn't measure with lots of ac to set teh gap for max L.. I just gapped it where I knew it wouldn't saturate for a first listen.. I think 10mH... the sound? - Ahhhh... much better... so folks, suck it up and buy another piece of iron for your filament supplies.. force that signal to go where you want it to go! :wink:

Peace,
Me
dave slagle
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Post by dave slagle »

those chokes are not amorphous but plain old GOSI (grain oriented silicon iron) the "trick part" of them is the tape thinness is .002 so it is a fraction the thickness of even M-2. Their original use was for use at 10,000hz so i suspect they are safe to use at audio frequencies :-)

dave
BruceMP
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Joined: Sat May 12, 2018 5:41 am

some filament choke possibilities

Post by BruceMP »

Thank you,spitfirehauser....I just purchased some of the filament you suggested,if you can help me with some settings to ensure decent prints,I will sign up to help out NO PROBLEMDo I need to change the tip on my hot end?
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