Valve noobie asks for help / advice

[cbutterworth]

Well the water analogy does make sense, but it still requires some thinking. The concept of equal pressure regardless of pipe thickness makes clear sense as does the conecpt of flow-rate.

Thanks Sy.

Charlie

[Renron]

Originally posted by cbutterworth
Ron,

You made me think for a second there! I am wondering if Broskie's table list current per plate and not for the entire tube. If this is the case, then I'll have to double my estimate of PSU current draw from around 18mA to 36mA! I'll go back and look at his original schematic and try to calculate current for his set-up and see if it comes out close to his table.

Charlie

Thanks SY You DID IT
I think we have a first here!!!!! see 2nd line post#1
The B+ Voltage is shared per the tube by each plate.
That way the B+voltage is rated at/by the valve spec. sheets and also as rated in John B's table at the end of the USERS GUIDE provided with his PCB kit.

Thanks Sy!
I'm on my way to brouse around in "The Red Light District"



I am very happy to know I was not the only one confused by the Aikido B+ values.

Ron

[SY]

Yes, but I lost EC8010, who is an actual engineer. So forget everything I said, it must be wrong.

EC, if I haven't already, I hereby officially recommend Shive and Weber's "Similarities in Physics." I've thoroughly annoyed my co-workers by modeling diffusion of gases through a barrier with electrical analogies...

I'm on my way to brouse around in "The Red Light District"

Good luck with that; EC and I did that for real last year in Amsterdam, and I'm afraid I damaged him a bit.

[Renron]

Originally posted by SY
EC and I did that for real last year in Amsterdam, and I'm afraid I damaged him a bit.

Oh do tell, I love a good story.

[SY]

Trust me, he has a much better story about me.

We were out at an excellent beer bar (Gollem) and started to walk (stagger, really) back to our hotel. A local guy, Erik deBest, was with us. We weren't exactly in the Red Light District, but sort of skirting around the edges. As happens there, a furtive guy with a small brown paper bag comes up to us, goes directly to ME out of the three of us, proffers the bag and asks, "Viagra?"

[Renron]

Sy,
No Doubt it was because YOU were the most sober of the three.

Cbutterworth,
Using the formula for calculating the min. size of the choke needed, I was lucky enough to end up at 6.045. I have read also that using the Fairchild Stealth FREDs will assist in prevention of ringing. Perhaps I should buy a 10H just to be safe.

Without spending $$$ on a choke, any recommendations for suppliers?

Is there a formula for determining the inductance value (choke size) of a transformer using a DMM?

This is a wonderful learning thread !!! THANKS ALL
Ron

[cbutterworth]

I am using the Hammond 193G, it is 10H. I cannot remember the price, but somewhere around the $30 sounds right. Try looking at the AES website www.tubesandmore.com

They keep many of the Hammonds in stock, although other suppliers such as Digikey can order them for you.

As for the FRED, I have no idea if it'll work, but as you already have the 6H choke, why not give it a try, if this choke rings, then maybe invest in a 10H.

Keep the forum informed, as we can all benefit from the input.

Charlie

[Renron]

Charlie,
Thanks for the link, I'll try the 6H and let the group know what happens. BTW what does ringing sound like? Is that a dumb question?
Ron

[jayme]

If a choke is "ringing" you likely won't hear it. You'll have a B+ that is not quite stable. It will have some overshoot. Model it in PSUD2 with a slight change (+1mA) in current draw. For a portion of a second after the change, you'll see the B+ swing past the target voltage, then reverse and swing back up, again missing the target. Typical underdamped filter response.

I've had some issues with it in my CLCLC filter. I had two 15H chokes as each L....without HUGE amounts of capacitance, that shows severe ringing.

In my case, the ringing showed up as subsonic woofer pumping.

[Renron]

Jayme,
Wow! That's interesting.....I never would have suspected "Ringing" to manifest itself in that way. Do you suspect it was due to the Cap sizing in the filter or the desgn?

I do recall reading (but not where), that the first C should be no larger than 8 Ohms, and the last should not be "Huge". Whatever Huge is.

Anybody else have different results from "Ringing"?
Ron