WRT ESR and Xc calcs, not that I'm aware of. I just use the same old formula as everyone else.
Richard is definitely the pioneer here.. I can just see what it has to offer for my builds.. Math is fine for LF, its the other issue/s that I'm more concerned with. Cheers.
North Carolina Sixers.. had to google that one.. was thinking you were meaning the Sydney cricket team for a while there.
Thanks trobbins, I'll need some time to think about what you write, straight off the bat it's a bit over my head. I appreciate the time you've taken.
Mods please combine with post #25 at will.
trobbins when you say ESR, are you meaning Xc?.. I don't think so, but I'm unsure.
If the model used is to replace the cap with a voltage source and series resistance, then a simple variation is to change the value of that series resistance. As a model, that doesn't quite equate to a capacitor's reactive impedance and series resistance, and how that would affect circuit operation. Changing the model's voltage source series resistance is equivalent to changing the capacitor's ESR, and although it's not the same as a change in capacitor's reactive impedance, it may provide some insight.
Of course Sydney 6ers. I'm trying to get excited about T-20. We got some TV coverage of BBL up here for 2 seasons but not this year. I picked the Sixers to cheer for this year because they're 6 ers. I already have a NC Hurricanes team up here to cheer for so Hobart is out.
If I can string a few days off I like the international test series, depending on venue, seats and weather it can be really good. Australia vs Sri Lanka at the moment. World cup semi final came to my home town two years ago, weather was good, seats were great, really enjoyable.
BBL/ T20 I see the appeal and have enjoyed it also. Live at the game its a bit kitch (four or six runs and they go nuts on the PA system with crazy music), but still enjoyable, and its a good night out especially if you're with kids. I would really like to attend one of the many sports that you guys cherish in the US sometime, baseball or NFL etc.. I've limited understanding but I think it would work out just fine (a bit like my capacitor issue, once I figure out what I need to figure out
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Unwanted coupling would come if someone attempted to use a supply rail like this to feed more than one stage. In that sense it is not a proper supply rail at all, but just local decoupling.
I don't understand the modern obsession with CCS. They have a role to play in electronics, but it is daft to sprinkle them everywhere as some seem to do.
I don't understand the modern obsession with CCS. They have a role to play in electronics, but it is daft to sprinkle them everywhere as some seem to do.
Thanks DF96 re the unwanted coupling explanation. Seems I'm good to go if I keep the cap value at 20uF or so, I think to understand your comment re CCS, or at least the sentiment behind it, yet the CCS in my designs allow for functionality which otherwise would not be possible, and I'm happy about that.
Cheers.
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Please do NOT quote the entire post directly above yours when replying.
They're intended to be a single stage solution. This particular topology is one I have used in SE amplifier driver stages with ITs, and local cap decoupling, it prevents large variations in plate current with tube changes with very high transconductance triodes/triode connected pentodes I typically use in my driver stages. It also works well to isolate the supply from the driver stage - and is actually much cheaper to implement than multiple pi-filters to get the ripple down. The Achilles heal of the approach is both the size and quality of that decoupling capacitor to assure that the supply looks like a voltage source at audio frequencies.
When I don't use IT coupling I typically go with a hybrid driver circuit using a cascode CCS/follower with high transconductance triodes/triode connected pentodes. This gives me a gain = mu, low output impedance and lots of linear swing which is why I do it.
The GM70 amplifier (picture attached) uses the approach discussed. The 300B amps just use a hybrid driver based on D3A and cascode depletion mode mosfets. (It's just a glorified mu-follower.)
Practical uses for CCS shown..
When I don't use IT coupling I typically go with a hybrid driver circuit using a cascode CCS/follower with high transconductance triodes/triode connected pentodes. This gives me a gain = mu, low output impedance and lots of linear swing which is why I do it.
The GM70 amplifier (picture attached) uses the approach discussed. The 300B amps just use a hybrid driver based on D3A and cascode depletion mode mosfets. (It's just a glorified mu-follower.)
Practical uses for CCS shown..
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Kevin, could you please provide some insight as to what value of capacitor meets with your criteria as stated above?.. does it align more or less with Mr Sears calculations as per the link at the OP, or did you find the need to increase the value?. This would be very helpful information to me. Thank you.
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I originally resonated the primary of the IT using a smaller capacitor value, I actually found it did not sound as good or work as well as I might have expected.. LOL This was to compensate (so I thought) for insufficient primary inductance, worked and measured exactly as predicted.
I would say the criteria used in the article would be the minimum and I would probably aim for around 1 - 2Hz typically as a target.
I still use this approach with ITs and high transconductance driver tubes in some designs and find it works well.
I would say the criteria used in the article would be the minimum and I would probably aim for around 1 - 2Hz typically as a target.
I still use this approach with ITs and high transconductance driver tubes in some designs and find it works well.
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