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Cap "breaker-inner"

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Posted on October 17, 2020 at 09:32:16
1973shovel
Audiophile

Posts: 9227
Location: Greenville SC
Joined: February 25, 2007



Inmate Airtime and I were discussing capacitors, specifically Teflon capacitors, which are noted for requiring a notoriously long break-in period, often stated at 400 (or more) hours.

He sent me the above circuit, which is easy enough to build. But my question is, is 9 VDC enough to have any effect on the Russian FT series of Teflon caps, for example? Mike Samra used to post that the FT-3 200 volt caps were good at over three times that voltage. I've got some 600V FT-3 Teflon caps, and feeding them 9 VDC would seem like a flea on an elephant's ass.

Before anyone suggests "Just put them in the circuit and listen to them", if they do roller coaster in performance for 400 hours, it may be difficult to recall what the previous caps they replaced sound like. This device may help in that regard, but I'm wondering if I should apply higher voltage (increasing the voltage rating of the 22 uF cap, of course) closer to the working voltage of the caps being burned in.

Thanks.

 

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RE: Cap "breaker-inner", posted on October 18, 2020 at 14:05:59
Davey
Audiophile

Posts: 2116
Joined: September 26, 2013
The (polarized) 22uF capacitor is in the circuit backward. I don't think I would trust much about that circuit, or the person who designed it. :)

Dave.

 

Won't this have the same effect as Charged Couple, posted on October 18, 2020 at 15:55:09
Cougar
Audiophile

Posts: 3786
Location: SoCal
Joined: June 25, 2001
In a crossover? Don't know how the caps will sound once they are removed from the 9volt battery or other power supply personal but I have read that once the caps are removed from the 9 volt source they sound like crap for awhile.

 

But wait: there's more..., posted on October 18, 2020 at 16:48:49
Steve O
Audiophile

Posts: 9800
Location: SE MI
Joined: September 6, 2001
...a good 9VDC source will have low impedance effectively shorting out the line level signal if both are connected to the circuit simultaneously. So the caps being burned-in see no signal, only 9VDC...assuming the polarized cap hasn't been damaged from reverse polarity.

 

RE: But wait: there's more..., posted on October 18, 2020 at 18:28:56
Davey
Audiophile

Posts: 2116
Joined: September 26, 2013
Assuming you had the correct capacitor installed....and the correct direction....this is essentially just a phantom power circuit. So the signal would couple via the capacitor and ride on top of the 9VDC on the "burn in" capacitors. So, you wouldn't damage your signal source.

But the whole concept of it is ridiculous to begin with and a waste of time.

Dave.

 

RE: But wait: there's more..., posted on October 18, 2020 at 20:41:32
rivervalley817
Audiophile

Posts: 2180
Joined: June 15, 2020
why do you guys think that cap is backwards?

with regards,

 

As the circuit is drawn and assuming the 9V supply..., posted on October 18, 2020 at 22:45:00
Steve O
Audiophile

Posts: 9800
Location: SE MI
Joined: September 6, 2001
...behaves something like a true voltage source (approaching near zero AC impedance), it will shunt any AC signal to ground leaving only 9VDC across the caps being broken. The circuits I've seen attempting to passively superimpose an AC signal on a DC source do so by placing a large value resistor in series with the DC supply.

 

RE: But wait: there's more..., posted on October 18, 2020 at 22:52:41
Steve O
Audiophile

Posts: 9800
Location: SE MI
Joined: September 6, 2001
As drawn, the negative terminal of the 22uF cap is tied to the positive terminal of the DC voltage source. When an electrolytic cap is reversed biased as this one would be, the insulating oxide layer breaks down and the cap becomes a resistor allowing DC current from the voltage source to flow thru it. This situation typically damages a polarized cap and may cause the cap to fail with a spectacular and messy explosion.

 

RE: As the circuit is drawn and assuming the 9V supply..., posted on October 19, 2020 at 07:22:25
Davey
Audiophile

Posts: 2116
Joined: September 26, 2013
I think the assumption is the 9 volt battery does not have zero internal resistance. There really should be a resistor between it and the rest of the circuit.
The whole thing is a joke and "designed" by somebody who had no clue what they were doing.

Dave.

 

RE: But wait: there's more..., posted on October 19, 2020 at 08:41:46
rivervalley817
Audiophile

Posts: 2180
Joined: June 15, 2020
'the negative terminal of the 22uF cap is tied to the positive terminal of the DC voltage source'

yes, that's the direction of the current flow ... the whole DC circuit 'flows' to the positive of the line level source, which actually carries the 'negative' audio signal right? the line level's negative flows to the negative terminal of the battery ... are you saying the battery should be reversed as well?

when you say it converts that bi-polar cap to a resistor I agree, but that circuit is also treating the battery as if it was a 'pre-charged' capacitor, and the whole thing is dumping DC into the line level source in reverse ... I was thinking that bi-polar cap should just be a high value resistor instead ... on the other hand it doesn't make much sense to reverse charge the line level output ... that seems like 'bad ju-ju' to me

regards,



 

RE: But wait: there's more..., posted on October 19, 2020 at 10:08:32
Davey
Audiophile

Posts: 2116
Joined: September 26, 2013
Do you see DC current flowing anywhere in that circuit????

Dave.

 

RE: But wait: there's more..., posted on October 19, 2020 at 10:41:57
rivervalley817
Audiophile

Posts: 2180
Joined: June 15, 2020
is that not a 9VDC battery in circuit? is there any switching inverter circuit there?

this thread took off because 1973Shovel was concerned that 9 volts weren't enough correct?

what am I missing?

 

Thanks for the feedback, posted on October 20, 2020 at 03:53:43
1973shovel
Audiophile

Posts: 9227
Location: Greenville SC
Joined: February 25, 2007
What brought this about was me wanting to try Teflon capacitors in my tube phono's RIAA equalization. Some knowledgeable Asylum members (Eli Duttman and Mike Samra, to name two) have speculated that Teflon caps in the RIAA might never break-in in that portion of the circuit.

On the other hand, there's been posts by the likes of John Curl, and others who've said they used Teflon caps in their RIAA, saying they're better than polystyrene, which is what I always use in the RIAA network.

I want to try Teflon caps, but was looking for a way around the "they'll never break in" dilemma. I could easily expose them to DC, but since the speculation is that they need to see both DC and AC, I had hopes for that circuit I posted.

I'll tack the pF value caps across the output caps on my tube line stage for a couple of months, then try them in the phono circuit.

Thanks again.


 

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