Actually if someone wants to confirm my results it seems to explain some interesting issues.
That would be too easy. Ed does not like doing an experiment and presenting his results for general conversation.
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Cal, thanks for corresponding with me. I would PREFER to talk about the CTC Blowtorch circuits, or just as well, the Vendetta Research phono stage circuits. However, I have no control over the input here. In my advanced age, I am giving up more info than the past, but I can only respond to those who are really interested.
The current source, to first order, doesn't have to be particularly low noise, although we would probably go to the trouble to make it so for good measure.
The principal complexity is having a well-isolated power supply, per channel, with sufficient voltage. Batteries are cumbersome, but EUVL has faced that problem with his I-V converters for DACs. Others (sorry have forgotten who they were---Gerhard?) have presented in that EUVL thread some designs for floating supplies that are mains-powered, with carefully selected common-mode chokes and so forth. I haven't tried to build them as yet.
Rather than just describe this stuff in here, it might be less confusing to start a new thread, and since the circuitry is not all that elaborate, actually build something and present the results. I have a fair number of SK170s and enough SJ74 to do this. I am preoccupied with another project but I'll try to get round to it.
I think this is what Ed is saying.
Wire diameter vs conductor spacing vs conductor skin effect is going to affect send/return conductor fields cancellation/loop inductance and effective conductor area.
Ed, what is the conductor spacing ?.
Dan.
Max that is actually a lot of variations to take into account. Considering all he gave originally was a piece of wire of a certain gauge folded upon itself. No distances besides the length of the wire and the gauge originally. You could make many variation right there. I don't think I would set up an experiment without some strong conditions that could be varied one at a time.
> The principal complexity is having a well-isolated power supply, per channel, with sufficient voltage.....
I did not put this idea into practice because the whole circuit was not made simpler and more elegant as a result.
That was the case with the CEN IV when compared to the original Leach circuit.
Nevertheless I still think that it was very clever.
My next questions would be :
1. While JFETs and MOSFETs are not perfect penthodes, the Id variation with Vds is still small.
So would adding 4 caps to the cascode gate voltage network not improve PSRR ? (See attached.)
2. If it does, is there any disadvantage of using C1~C4 ?
3. Why not go one step further and use current regulating diodes (JFET CCS) to replace R16, R19 ?
Patrick
.
I did not put this idea into practice because the whole circuit was not made simpler and more elegant as a result.
That was the case with the CEN IV when compared to the original Leach circuit.
Nevertheless I still think that it was very clever.
My next questions would be :
1. While JFETs and MOSFETs are not perfect penthodes, the Id variation with Vds is still small.
So would adding 4 caps to the cascode gate voltage network not improve PSRR ? (See attached.)
2. If it does, is there any disadvantage of using C1~C4 ?
3. Why not go one step further and use current regulating diodes (JFET CCS) to replace R16, R19 ?
Patrick
.
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Using solid wire you can keep the spacing the same, loosen it or tighten it. The complex FFT allows you to look at the phase angle which is inductance related.
But the idea is to let someone else try the experiment and without biasing them seeing what they observe.
For the benefit of non-scientists, this is not how science is done:
Person A: "I did an experiment yesterday and I got a result which would surprise you (if you knew exactly what I did, but I'm not going to tell you)."
Person B: "Why not tell us exactly what you did, what results you got, what existing theory would predict, and how your results differ from this? Then we can try to replicate your results and/or provide an explanation using existing theory if possible."
Person A: "No, you do a different experiment (but vaguely similar to mine) and see what you get."
Person B: "Why should we bother, when the most likely causes of your results are either measurement error or misunderstanding of existing theory?"
Person A: "Then you accept that my results stand, and I have discovered something which all the experts have missed for decades?"
Person B: "That isn't quite what we said."
Person A: "I did an experiment yesterday and I got a result which would surprise you (if you knew exactly what I did, but I'm not going to tell you)."
Person B: "Why not tell us exactly what you did, what results you got, what existing theory would predict, and how your results differ from this? Then we can try to replicate your results and/or provide an explanation using existing theory if possible."
Person A: "No, you do a different experiment (but vaguely similar to mine) and see what you get."
Person B: "Why should we bother, when the most likely causes of your results are either measurement error or misunderstanding of existing theory?"
Person A: "Then you accept that my results stand, and I have discovered something which all the experts have missed for decades?"
Person B: "That isn't quite what we said."
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