Please suggest practical DIY uses for these BIG oil caps

[cdwitmer]

I was recently given a half dozen 100uF/400VAC oil capacitors, all self-healing type, very visually impressive cans (ceramic insulators, threaded lugs, etc.) that seem to me to be WAY too large (9 x 12 x 3 inches) to use on any reasonably manageable amplifier. I'm wondering if there might be other uses for them them in the context of DIY audio, such as helping to clean up the mains AC power. In such a capacity their sheer physical size would not be as much of an issue. I'm used to seeing smaller film capacitors used across the AC line, and many thousands of uF used in DC blockers, but don't recall having ever seen someone using 100uF oil caps to clean up their incoming AC electricity. (They're definitely not something most DIYers would go out and purchase new for a project!) The need for bleeder resistors is taken as a given with such large capacitances on the AC line . . . Anyway, at this point I'd be grateful for suggestions as to what might be good uses for such capacitors in DIY audio. Thanks!

-- Chris

[refference]

Chris ,

IMHO , there are two good ways , you can use these caps :

1 ) In a power amplifier CHOKE INPUT power supply .

2 ) In a VOLTAGE DOUBLER working together with
ultra-fast / soft recovery diodes, to feed any power
amp , so you can save a few ( may be many ) pennies
with the power transformer , with much low secondary
voltage but able to give the double of current demand .
Or even for a bench-top laboratory variable and ( tube or
mos-fet ) stabilized power supply , for testing purposes .


In the two cases above , all the stuff assembled in a separated
chassis , due to the extra-large size of caps .
By the way , oil capacitors are the best capacitors “ to handle “
with high ripple currents , they are extremely fast , extremely
reliable , and if the oil does not leak , they are forever .
The oil cap’s behavior is excellent , at any work condition .

May be another people has more suggestions .

Carlos

[audiowize]

Check your speaker crossover and see if you can use them there. That's an awesome use... BTW, plenty of people use those in amplifiers. Two of them is enough for a reasonably large 2 channel tube amp.

[cdwitmer]

Thanks, AUDIOWIZE. I'm strictly a fullrange single driver user but some of my best friends have passive crossover networks in their loudspeakers and I know one fellow in particular whose caps probably need an overhaul and he might be willing to give an outboard crossover a try.

Both you and REFFERENCE suggest using them in power amplifiers and I suppose I should at least look into possible practical ways of doing that before dismissing the idea for myself. Perhaps if the power supply was on one chassis and everything else on another, connected by an "umbilical cord" . . .

Especially since I am getting ready to build a tube amplifier with a voltage doubler and choke input P/S . . .

Any additional comments on the two suggestions received so far, or possible different applications, would be most welcome.

With gratitude,

Chris

[tinitus]

I did think about speaker crossover, but they seem to awfully big

But they could be used in series with a battery loading the midpoint

That would transform your 400uf into 200uf, which MIGHT be used fore mids highpass seriescap in a 3way xo

Look in "Elsinore" thread, where Joe shows how to(one of the later posts)


Might also be used in paralel fore highpassing a small 2way with subs, just to make a small 5" move less

[refference]

Originally posted by audiowize
Check your speaker crossover and see if you can use them there.

Originally posted by tinitus
I did think about speaker crossover, but they seem to awfully big

Hi guys ,

Sorry to say that , but IMO these caps are not appropriate to
use on crossover network , not due to the extra large size , but mainly because they are VERY inductives ( they are built like a coil ) and their behavior is unpredictable .

Regards ,

Carlos

[cdwitmer]

I'd be happy to share these capacitors with a friend if it turned out that someone I knew could put them to good use in ANY application, but if I'm the one to be using them, my personal interest is definitely more towards using them in a power supply (although their physical size is an issue to be dealt with) or perhaps on the AC line in some sort of a power filtering/conditioning application.

For example -- I'm just tossing this out as a possible idea -- I have "out in the barn" a 10kVA isolation transformer, a 6kVA isolation transformer, and a pair of 2kVA "balanceformers" (transformers with equal split secondaries suitable for balanced power); I was thinking of having an electrician come install the 10kVA and 6kVA units to protect most of the house, with the two 2kVA balanceformers dedicated to sensitive equipment in my home office and my listening room.

Here is an image taken from the Felicia Power Conditioner concept that has been introduced here and elsewhere on the Internet --



In that application, the 0.9A power conditioner used an 18uF capacitor for C1, bypassed by smaller capacitors for C2 and C3. What I'm envisioning is using the 10kVA transformer as T1 and the other transformers as T2. If one was to simply increase the capacitance of the capacitors in proportion with the increased multi-kVA current ratings of the transformers, 100uF would actually be on the small side. (Not that every component necessarily needs to be scaled up in equal proportion.)

Any thoughts?

Thanks,

-- Chris

[rdf]

Originally posted by cdwitmer
I was recently given a half dozen 100uF/400VAC oil capacitors, all self-healing type, ...9 x 12 x 3 inches...

That sounds...odd. The ASC 100uF, 370VAC X386S is 4.75" tall with a diameter of 2.5". Your caps have roughly fourteen times the internal volume.

[wlowes]

Originally posted by cdwitmer
I was thinking of having an electrician come install the 10kVA and 6kVA units to protect most of the house,

I am no expert on isolation transformers, but would it not be dangerous to wire a portion of your house with balanced power? Ok for your amp, but your house neutral would be hot. I think its dangerous to plug two prong devices like lights into that circuit.

You could make one heck of a power conditioner for your audio though.

I just put a 500 Va isloation transformer in front of my audio and am very pleased with the results.

[zigzagflux]

Originally posted by wlowes
I am no expert on isolation transformers, but would it not be dangerous to wire a portion of your house with balanced power? Ok for your amp, but your house neutral would be hot. I think its dangerous to plug two prong devices like lights into that circuit.

NEC Article 530 G lists the requirements for the use of 60-0-60 balanced power. Nothing really all that significant, other than the circuit is to be dedicated for audio/electronic use (no problem for the DIY'ers) and that all receptacles are to be GFCI protected (which I suspect most DIY'ers have not done). So, yes, it is completely illegal to use lights, appliances, or general use receptacles on balanced power. Fundamentally, it should be used for just that rack or corner of your living room.