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Posts by wakibaki

A simple (not so simple) way round this is to use a single regulator and make sure that it is on the correct side to pass any DC bias in the returned current from the amplifier. Unless you want to match each regulator to each amplifier this presents its own problems.   You might find that with a suitable opamp, the opamp/transistor circuit I drew can actually be built to reliably outperform the regulator circuit in terms of wasted power. It can certainly be built to...
Good question Kim, I should have paid more attention.   We're not dealing with DC here, we're dealing with AC. As long as the the net current is zero there will be no problem, there are some big caps there. What I should have thought of, and which is why he is getting the result he does, is what happens at DC. If there is a net DC bias that exceeds the leakage through the caps and the adj. pin there could be a problem.    Sorry goldpoint, your point is well...
  No I don't see. It doesn't sound at all likely to me. You obviously did not monitor the ground-to-opposite rail voltages when you did the tests. If the ground point moves toward the positive rail, the negative rail must move toward the positive rail by double the amount, because the 2 resistors and the zener diode keep the regulator adj. pin at 1.25V negative of the centre point, and its output therefore at the centre point.   As Kim said, the 2 outputs should be at the...
I think that with just 1 regulator the sinking impedance and the sourcing impedance may not be symmetrical. This would have to be tested, at least in simulation. The advantage is that there are no problems with matching and no necessity for the ballast resistors with a consequent lower output impedance and no possibility of power being wasted if the two regulators end up producing slightly different voltages.   It just illustrates IMO, the reasons to stay away from...
  There is only one ground. How can half of it be regulated?
Looks good to me Kim, but maybe some of it is unnecessary...       w
Somebody else look at this and tell me if it works, it's 4:25 am here:-       Maybe you could even get away with this:-       w
Here's an idea I've been playing with...     I recently 'discovered' how to make circular PCB features.   I used to make footprints for tubes by drawing a silkscreen circle, and then using trigonometry to calculate the positions for the pads to the nearest thou. It works, but it's cumbersome. Then it occurred to me I could use the 'block rotate' facility to do this. Draw a circle round the sheet center, place one pad at a known distance, select a...
I think tomb's characterization of the behaviour as resembling the Pied Piper and his followers contains an element of truth, but it is worth recognizing that there was a different piper before that and probably a different piper before that. At least one of those pipers though that increasing complication (such as introducing a ground channel) would automatically result in an increase in sound quality, but this is certainly not borne out by instrumented test. Of course...
J Epstein, thanks for the encouragement. Some interesting stuff on your site.   elliottstudio, thanks for the transformer data. nikongod, thanks for helping keep the thread alive.     I managed to get the heater supply board for the second build done. It should be working in the next couple of days.   Unfortunately some new symptoms have meant that the oncologist sent me for a CAT scan, the surgeon sent me for a PET scan and I'm keeping my fingers...
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