Re: High voltage capacitors in audio

On Jun 26, 8:23 pm, John Popelish <jpopel...@xxxxxxxx> wrote:
MooseFET wrote:
On Jun 26, 8:09 am, John Popelish <jpopel...@xxxxxxxx> wrote:
The Zs are just a way to consciously remember that every
piece of conductor has resistance and inductance, and so,
will produce voltage drop in response to current and changes
in current, respectively.

Note that I said "ideally". I was suggesting "Z"s be placed on
purpose. This can be just the way the wires go, small value resistors
or even lossy inductors.

It doesn't matter much how they are done, it only matters that
something like that be the case.

The ones over at the left are to keep RF out as well as to spread out
the current in the bridge. They are likely to be actually resistors.

Sorry I misunderstood you. I thought you were just labeling
the unavoidable impedance of those current paths. Have you
designed audio or other equipment in which you actually
added those components?

Yes, partly.

In one case: The impedances at the transformer connections where 0.22
Ohm resistors. The impedances in front of the regulators were type 77
- 0.25 inch toroids. The others were just the wiring.

The amplifier in question had a gain of about a million over the 850Hz
to 4KHz band. Without the 0.22 Ohms in the transformer winding, the
harmonics near 2KHz caused troubles. Spreading the current pulse out
decreased them enough.

In another case, we had several LM78XX regulators. The transformer
and bridge were in another chassis. Here in the SanFransisco area,
the AM radio station KGO seems to like to get into stuff. Keeping it,
the mains harmonics, the noise from the data computer and clatter from
other parts of the system out of the high gain electronics required
that there be EMI filters on everything coming and going and several
1.0 Ohm 2W resistors in the unregulated power distribution circuits.


I have added a capacitor across the secondary of
transformers to lower the resonant ringing frequency that
occurs when the rectifiers snap off, but not small series
impedances.

The recovery time of the rectifiers is the main way that the bridge
invents new frequencies.




.

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