AC Motor Start Caps for PS use

[alk]

That amp is going to be fat....the one in the pic is for 250V, i wonder the size of yours

 

[G]

I always thought this:

AC VOLTAGE:

The sum of the DC and Peak AC voltage applied to the capacitor should not exceed the rated DC voltage, nor should the RMS voltage exceed the Corona Start Voltage.

http://www.americancapacitor.com/Tech.htm

And I always knew this:

1.42 DCV per ACV

Working voltage (Wvdc, Wvac):

The maximum continuous voltage that should be applied to a capacitor. Rated voltages for DC and AC operation are usually not the same.



Thanks G however I need proof to both proove to myself and to my amplifier, I'm not about to waste many hundreds of dollars to buy high-capacitance PIO caps for my 50watt/channel just so all of the AC ripple gets passed through... :\

They're 25 PIO capacitors rated at 17.5uF of 440vAC each... I did good? sure as hell I did!! at 130uF/channel filtering!! all PIO

What type of circuit are we talking about? I'm thinking you should only need about ten of them for a satisfactory power supply.

 

[Layberinthius]

See for yourself.

 

[G]

See for yourself.

I mean what type of amplifier are you building? Single ended? Push Pull?

 

[Layberinthius]

They aren't small

The plan is to use about 5 of these each CHANNEL like this:

C1 is two 660vAC 8uF PIO capacitors in parallel
C2 is one 660vAC 8uF PIO capacitor and one 17.5uF 440vAC capacitor.
C3 is two 440vAC 17.5uF PIO capacitor.
C4 is two 440vAC 17.5uF PIO capacitor.

Total ma from the trafo is 230mA, total load is 230mA but varies greatly due to the amplifier being P-P.

 

[Layberinthius]

The simulation results as it stands.

The idea is to place 5 of these 17.5uF caps in a 525vDC power supply and see if I would benefit from any addition of capacitors wether it be in position C1-C4..

But eventually, ultimatley, finally... the idea is to use 5 per channel for B+ then use another 4 for each channel -80v Bias supply.

I am welcome to any suggestions or warnings

 

[G]

I'm not asking for the schematic. I'm just asking what type of circuit it is. Is it a big secret?

 

[Layberinthius]

NO I thought I said the circuit type...

Total ma from the trafo is 230mA, total load is 230mA but varies greatly due to the amplifier being P-P.

Push pull, I'll tell you the rest though.. KT88:VDV KT88

While some people don't do work in the morning, I do...

So mind me if I jump on here and don't give a reply for an hour or two.

 

[316a]

..

NO I thought I said the circuit type...



Push pull, I'll tell you the rest though.. KT88:VDV KT88

Hello ,
Thats a copy of the Hafler and Keroes version of the Williamson . Plenty of scope for improvement and modifications but I'd be very careful with regards to the size and layout of your chassis , especially with all those caps . It may be an idea to build separate chassis for the psu and amplifier stage and link the two with an unbilical cable . Otherwise build monoblocks .

cheers

316a

 

[Layberinthius]

Hello , Thats a copy of the Hafler and Keroes version of the Williamson . Plenty of scope for improvement and modifications but I'd be very careful with regards to the size and layout of your chassis , especially with all those caps . It may be an idea to build separate chassis for the psu and amplifier stage and link the two with an unbilical cable . Otherwise build monoblocks . cheers 316a

First off thanks for the reply, second:

Yes the whole project is based upon constructing two chassis for the PSU for each channel and I have about 4 by 2 foot of desk space for the two PSU's alone, the amp has the same just above it for two amp chassis, soo monoblock with seperate PSU and Amp chassis.

So I'm certianly not running out of space to put it however I may need to consider making the pair of PSU chassis a heavy Aluminium construct and the amplifier itself for each channel light a light Aluminium construct so I can actually do the modifications in moderate not-back breaking pain whenever I pick a side up!

 

[Layberinthius]

There is nothing like a real-life test..

I'll also see how things go if I do this:

C1 is 3x 8uF 660vAC PIO caps in parallel.
C2 is 4x 17.5uF 440vAC PIO caps in parallel/series.
C3 is 4x 17.5uF 440vAC PIO caps in parallel/series.

A much more safer and reliable prospect, however I do not know of the condition of these capacitors so I am currently winging it until I can test for leakage or damage to the container and proper test benching at the operated voltages with a mock PSU and dummy load.

I might also whack the box over to Lou's for him to find any abnormalities that I cannot /early/ before they are placed in any sort of series operation.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

 

[Masami]

Hi,
is it I can use the AC capacitor in dc condition with 1.414 x AC rating?

i.e.400vac x 1.414 = 565vdc?

 

[fdegrove]

Hi,

is it I can use the AC capacitor in dc condition with 1.414 x AC rating?

Yes, that'll work O.K.
Keep in mind that some AC line voltage caps (X, Y series) also sometimes contain a resistor to form a network in conjunction with the cap.
So check what they were made for before deciding to use them for anything else.

Cheers,

 

[Jonathan Bright]

Just something out of "left field" while people are discussing start/run polyprops. I notice that they tend to have more uF per dollar than most of the polyprops that local catalogues advertise for speaker X-overs. Has anyone used them in x-overs? Any thoughts?

 

[Layberinthius]

I believe this is quoted:

The best sounding capacitors for audio powersupplies, decoupling stages, speaker crossover filters, etc are Paper/oil capacitors.

http://www.machmat.com/sales/capapo.htm

 

[Jonathan Bright]

Yes, well that may well be true but as you may have seen the local (Aust) supply of PIO caps are v. expensive. I was still wondering if anyone had any comments about using start/run polypros in x-overs

 

[Layberinthius]

I've found it to be a lot cheaper to import old stock from the USA when PIO caps are reguarded...

Depends on if you think $50+ AUD for shipping is expensive or not

 

[Fuling]

Has anyone used them in x-overs?

Yup.
I could hardly believe my ears when I changed from quite expensive polyprops to cheap oil caps. The results where amazing, and when I did a direct comparison to a friends crossover that has the same caps as I had before I changed the difference was almost ridiculous. Everything was better!
Very much recommended!

 

[316a]

Oilers

I believe this is quoted:



http://www.machmat.com/sales/capapo.htm

Hello ,
Of course he's going to say that . Have you seen how many of the things he has in stock ?

'EB91's are the best valves in the world and possess , until now unheard of sonic abilities !'

Guess how many of these I have in stock ?

cheers

316a

 

[Layberinthius]

Managed to find this
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Start quote #1
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Written by Mike at 05 Dec 2002 16:41:13:
....."the AN Oil caps (not Jensen) are pretty dark sounding and not a panacea - although some claim that they need 300 hours break-in. I also thought of trying oil caps and poly in oil like the GE 97F which is current production, sold by Newark. I like the GE's a lot for power supplies and decoupling."....

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Start quote #2
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Written by Greg B at 04 Dec 2002 21:45:10:
...."and a 0.5uf AN copper in oil (new style) as a bypass. This is very smooth. So far, all other bypass caps, including some NOS paper caps, seem too bright. ".....

....."Maybe your source is bright? I have mixed feelings about PIO caps. I had some Jensens that I tried as coupling caps and hated them, so I tried to salvage some use out of them as bypass caps in a crossover. They ended up having much the same sonic effect, at first they seemed smooth yet detailed, but it shortly became obvious they were just masking things with their characteristic added distortion."......

....."Strangely, in the larger sizes - say 50 uF - needed to cross over a full range or big horn to a woofer, oil caps seem to sound the best, IME. Any theories about this anyone? "......

......."Anyone know where a good cheap source is for large PIO caps? I hear certain brands of motor run caps sound good. ".....

Greg B
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End quote(s)
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Quoted article

Jensen Coupling PIO's

Layberinthius:

Glad I chose Polyprops for coupling