Dual-inductor questions

ohshitgorillas · 1360

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Offline ohshitgorillas

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on: April 05, 2018, 01:41:51 PM
I have been doing some rewiring and have come up with a scheme that I think will allow me to fit two chokes, two 100uF Dayton pp film output caps, and a larger power capacitor without putting either of the chokes on top. It involves mounting the last power cap over the transformer using two L-brackets to make a C (one of the brackets is cut short), the bypasses for the first and second power cap can also fit on this mount--the first two power caps have to lay down parallel to the chassis for this to fit, so I replaced these with two caps having longer leads. Two Triad chokes can be mounted vertically/on their sides on either side of the power tube socket (I have cut off one of the mounting tabs to make mounting them this way easier, but they could still be mounted by a properly sized L-bracket and still fit). One tricky part is that the Dayton output caps will have to be mounted vertically as well to accommodate the chokes... they are just barely long enough to fit without adding some extra tall feet.

I have two questions regarding this...

1. I know that using two chokes allows me to use a smaller 3rd power cap, I read in another post in this forum that it could theoretically go as low as 5 uF but that it probably wasn't a good idea. I was wondering if 20 uF would be okay though? There are reasonably priced Russian NOS 20 uF paper-in-oil caps on ebay that a friend of mine has used on his Crack and on another project and they work well. I might be able to fit two in there given the amount of vertical clearance if 20 is too low (yes, I already know this is overkill and the benefits will probably be marginal, and that the Crackatwoa's power supply would stomp this mod... but at this point it's a matter of COULD I, rather than should I).

2. Any ideas for getting the output caps mounted vertically? Besides trying not to short the end closest to the chassis. My current best idea is L-brackets and adjustable pipe clamps... but I'm open to suggestions.

Thanks!

(edited to include more detail)

edit 2: it appears that the PIO cap I was eyeing to replace my current 100 uF film power cap is only rated to 160V, not 250; going up to 250V it looks like I could safely fit a 10 uF PIO cap in there but not much more. and in any case there are other options for power caps, too, but a friend of mine uses some of those and I know they're solid
« Last Edit: April 05, 2018, 04:32:16 PM by ohshitgorillas »



Offline ohshitgorillas

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Reply #1 on: April 05, 2018, 04:09:06 PM
Re: #2, I think I am going to use an L-brace with a mounting bracket, then use that to hold the capacitor via pipe clamp. I will also line the area around the chassis underneath the cap with electrical tape so that it doesn't accidentally short.



Offline Paul Birkeland

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Reply #2 on: April 05, 2018, 06:03:41 PM
I wouldn't make the third cap any smaller than your coupling caps.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline ohshitgorillas

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Reply #3 on: April 06, 2018, 05:22:33 AM
That makes sense, thanks. I am still going to put in a second choke, I think, to show it can be done if nothing else. I understand that realistically, benefits may be negligible, but theoretically there shouldn't be any issues with going CLCLC right? 1st two caps are 220 uF



Offline Paul Birkeland

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Reply #4 on: April 06, 2018, 05:51:51 AM
If anything make the first cap smaller and the last two 220uF.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline faskenite

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Reply #5 on: April 06, 2018, 01:09:28 PM
I know the square root of nothin about dual inductors.  But I do want to express my admiration for an excellent moniker.