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In Reply to: Sorry, no bangs on reversing 'lytic cap to DC. (long) posted by cheap-Jack on February 26, 2007 at 12:44:05:
If you want to hear those little caps go bang - you won't do it with 15 pitiful volts - hook some AC line voltage across them!It was a favorite apprentice trick at my first electronics job way back - wire a 100uF/25V cap to the end of a powercord - push it along the floor under some other guys chair further on down the test bench row - plug it in and our 240VAC would do the rest...!
Got the whole area's attention!
Follow Ups:
Hi.Allen, why don't you stick your finger to the live point of the wall socket & feel how you bang up?
.
Hi.We are discussing an technical issue of coupling caps.
Come up with some creative ideas or back off, please. Who needs lip services here.
Since you were lucky that the cap did not explode, here are the technical bits.Electrolytic capacitors are commonly made with two layers of metal physically separated by a dielectric layer of material that is bathed in a liquid (sticky) electrolyte. There are multiple failure modes, but when the electrolyte goes bad and causes increased resistance and internal heating, the can will bulge and the capacitor can explode (provided that the relief vent did not work) and spray hot electrolyte, shrapnel of aluminum and plastic, noxious fumes, and even purple smoke everywhere.
Hope you can learn something from your mistake.
Hi.Did you read my posts at all?
I am seeking technical advice on cross-parallel 'lytic caps in voltage gain stage application, where one end is hooked to a very very low DC voltage & other end MORMALLY zero potential for I/P coupling.
What does such application to do with your 'tytic cap textbook defination. I can give you better ones if you want.
Russ has come up a thoughful supposition: DC inrush from the driving components. Yes, he is right but I can only consider such DC inrush as an accident which can happen to tube or SS topology regardless.
As I posted earlier, I try to eliminate the use of any I/P coupling cap as much as possible for any tube voltage gain I/P stage which includes my tube phonostage. We don't want any capacitive componets in the signal paths at all unless absolutely needed to be there. Like grid bias with grounded cathode.
Check up any tube amp designs, do you see any I/P coupling caps commonly used at all?
The post above was from my own personal experience as an engineer.If you drop the attitude and are willing to engage in dialog instead of diatribe may be the folks around here would be more inclined to help you out and examine the problem you're describing.
Care to post those IEEE papers so others can read them as well?
regards,
Hi.Let me say it again: I seek technical advice in using ying-yang parallel tantalum caps as instage coupling.
Not just what would happen in a general situation when a polarized 'lytic cap hooked up directly to a HV. Who doesn't know it will blow up? So your "own personal experience as an engineer" would not be found helpful to me here if that was what you can come up with.
I surely want to read something from you more up-to-the-point.
Thanks but no thanks.
c-J
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