From an audio forum... FR4 question

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use

When required, I tend to use two polar types 'back to back' and apply a polarising voltage via a high resistance to the centre point.

For the most part a single polar type works well though provided that the A.C. voltage across it doesn't exceed that ~ 100mV level.

Graham

On Mon, 14 Nov 2005 01:14:44 GMT, Ted Edwards wrote:

Good ones. I've added them to my list:

5N, 6N, 7N (as in 99.99999 pure copper) acceleration agressive air articulation authority bass transient response blackness bloom bright burnin (cables) clarity color confused congested continuousness crisp delineation of inner detail dynamics edge effortlessness etched extension fast bass free-flowing ease glare grainy granularity hangover hard harmonic completeness hashy holographic honesty image specificity impact jump layering liquid liquidity liveliness lush macrodynamics microdynamics macro-to-micro intensity musicality openness pace quantum purifier reference refinement relaxed roundness reveal single-crystal copper slam slow bass smear soundstaging space sparkle effect spatial resolution speed stunning (everything is stunning) thin tight tight (bass) timbre tipped-up transparency truth unfussiness wire direction

John

First a little math: Time constant T=R*C or T=(10^6 ohms)*(2*10^-9 farads) = 2*10^-3 seconds. That means it would take *two* milliseconds to discharge about

63 percent of the energy. Therefore, it will be impossible to "dump most of that 100mj into a 1Megohm load in 1ms".

There are a number of relays that can act in the millisecond region (but those cannot stand off even 500V), and ways to impliment a mechanical switch (which could withstand the 10KV) for closure that is controllable to give 1mSec closure within a few percent on timing.

An SCR might work, but how do you propose to shut it off? It would stay on until the current drops below its internal threshold in the tens of microamp region. One could do that by forcing the gate negative (but no more than 5V negative so that the junction does not zener), but one must extract all of the anoe current until the SCR itself goes off (all of the stored charges inside are removed).

BTW, a relay *is* solid state (metal) !

[snip]

If you can figure out how to do that please let me know.

Robert

In article , John Larkin wrote: [...]

They are, they are and they are $300 (about).

Almost every oscillator will change frequency when you turn the PCB over.

I believe all SC cut crystals are used in ovens.

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kensmith@rahul.net   forging knowledge

I'd rather wear the safety glasses.

Robert

A measurement between the load and transformer should tell you where the extra current is going.

A novel circuit that is interesting to look at though. I'd never thought about a single 5V pump of the rail and a simultaneous 5V swing of the output.

Will the output reliably swing from 0 to 10v in about 50nS? A possible killer might be load capacitance and the effective transient current load on the 74AC241.

What might be other ambushes?

--
Tony Williams.

[snippage]

My one wasn't sensitive to acceleration; it appeared to be a steady-state phenomenon. I could stress (i.e. bend) the board a little, and the frequency would change, and would've stayed changed had my loop not pulled it back.

Regards, Allan

Nah - it's all because of "Global Warming" and that's because the US did not sign the Kyoto Treaty. ;-)

The dirty secret is that they all buy their wire from the same few mills.

John

In article , Fred Bartoli wrote: [...]

except: If a non-linear part anywhere in the system generates harmonics near or above the gain crossover point, they can be boosted. If the phase shift is within 60 degrees of 180, there can be peaking at the harmonic's frequency.

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kensmith@rahul.net   forging knowledge

In article , wrote: [...]

^ Insert the word "very" as marked and I'll believe you but without it, you would have a very hard time proving it if it ever happened.

I've never seen a crystal under 0.5PPB/G

This sounds like it wasn't actually the crystal that was causing the shift. Perhaps the capacitors were being stressed and changing values.

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kensmith@rahul.net   forging knowledge

Can I use the word 'particularly' instead?

Yes, I had also considered that it might be caused by a 1uF MLCC in the loop filter. (I don't recall the dielectric material, but it was a physically large part (1206?).) Alas, this design has been retired, so I won't have a chance to open the loop and find the real cause of the problem.

Regards, Allan

That'll work too.

[...]

SMD 2520 is a physically large part. Is that the size of the 1uF? If it was 1uF and 1206, this couldn't have been very long ago and the material had to be a very high K one.

Your designs retire early. It must be nice.

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kensmith@rahul.net   forging knowledge