I built it. My oscillioscope which can show up to 20MHz and 500uV did not detect any ripples on the rails at all. It only appeared as a thin flat line across all frequencies.
It was an easy, no hassle build. I soldered the boards, connected to the raw supply, turned the voltages to the desired +-/15V, and it was done.
The new CCS is nice. It is very stable. The current is determined by 0.66V/R1. I have R1=3.9R, which gives me about 170mA. Every time I touched the heatsinks, I felt the same warmth. Never cold or hot.
The voltage drift is very small. I initially used 5k trimpot for R10 and 470uF electrolytic capacitor for C2. The drift was even smaller. But since I favoured film caps, I used 27k for R10, 2.2uF MKT for C2 (should be bigger if for full range) and put a 1k trimpot between the gate and source of the JFET, the voltage drift became higher, but no higher than 200mV, and this is more than acceptable to me.
This is rock-solid and very stable, like v1, with new enhancements in lower output impedance extending to high frequencies, even more stable CCS current, very small output caps which allow using film caps, and proper remote sensing configuration giving much higher sonic resolution.
Hi, v1 fans, you have something to do now.
It was an easy, no hassle build. I soldered the boards, connected to the raw supply, turned the voltages to the desired +-/15V, and it was done.
The new CCS is nice. It is very stable. The current is determined by 0.66V/R1. I have R1=3.9R, which gives me about 170mA. Every time I touched the heatsinks, I felt the same warmth. Never cold or hot.
The voltage drift is very small. I initially used 5k trimpot for R10 and 470uF electrolytic capacitor for C2. The drift was even smaller. But since I favoured film caps, I used 27k for R10, 2.2uF MKT for C2 (should be bigger if for full range) and put a 1k trimpot between the gate and source of the JFET, the voltage drift became higher, but no higher than 200mV, and this is more than acceptable to me.
This is rock-solid and very stable, like v1, with new enhancements in lower output impedance extending to high frequencies, even more stable CCS current, very small output caps which allow using film caps, and proper remote sensing configuration giving much higher sonic resolution.
Hi, v1 fans, you have something to do now.
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The picture in post 1898 is only a wiring guide with perfboard. With standard ExpressBCP I can't find the symbols for the right sizes of the transistors. Note that the MOSFETs were drawn as TO-220 type but should be TO-247. I also soldered all gate stoppers directly at the MOSFET legs.
P.S. Restored to proper sizes and better layout now. The picture has been updated.
P.S. Restored to proper sizes and better layout now. The picture has been updated.
output capacitor
http://calex.com/pdf/3power_impedance.pdf
Is it useful to follow these instructions in choosing output caps?
http://calex.com/pdf/3power_impedance.pdf
Is it useful to follow these instructions in choosing output caps?
The proper RC Zobel is already there as you can see on the ccts. The paper you linked is correct in general. Because the termination is a sensitive matter, that is why a film cap is specified there, so the resistor should surely determine it without uncertainty due to widely variable electrolytic specs, also not stable with heat and aging. To guard off bad interaction like oscillations or performance degradation when applying these ''speedier'' ccts, its advised to check all is well with an oscope on the supply lines (see no wiggles). If there is some local decoupling on the audio circuits already fixed, there is chance for incompatibility, especially if there are very small value/low ESR capacitors across supply lines to ground. Its a total reg/audio client system with many factors and parasitics, oscope is your friend and decoupling can be deleted or altered locally on the client boards if problematic cooperation occurs. V1.0 is designed with less edge performance but has broader tolerance, it can always be employed with remote sensing to enhance it even, if the situation is decidedly reactive with no solution when with V1.2. Performance gains are seldom a plug n' play game in a total system, although V1.2 has shown good behavior in compatibility up to now. That was one of the main goals of the independent beta testing effort btw.
That is nice. Can I export the component and import it into the general component library so that all my new files can use it? If so, have you got a resistor with 2 x 2.54mm handy?
Regards,
Bill
It depends on the actually load. The output of the regulator not only sees the output capacitor, but also the load, including the local bypass capacitors. The whole should be treated as one unit.
We often hear comments that one regulator is good and another one is not so good, or for the same regulator, one says it is good and another one says it is bad. I think for a given well designed regulator, it is always good by itself, it is the interaction of the regulator with the load that determines if the regulator can perform well or badly.
From the output of the regulator to the circuit board, there are wire inductance and resistance. The circuit has parasitic capacitance. The LCR forms a resonant circuit.
I found with my opa627 buffer, there is input capacitance that causes resonance. I use a 2.2uF film capacitor in series to 1R resistor as local bypass / damping circuit and this completely kills the resonance.
Thanks for the explanations.
Just what I was looking for.
The engineering of this is very high level.
Hats off to you.
Doug
Bill,
Open the file I sent, with the arrow pointer tool (top one lefthand side) select the symbol, from the list across the top of the screen (File, Edit, View, Component, etc.) select Component/Save custom component... Now it will be in your library. Then when you go to place a component and go to the pull down list, you'll see it in the first group - custom components.
So, you know, I made it in about half a minute, it took longer to zip and send than to make. I don't have a 2 x 2.54 resistor, but, you should try making one.
Start by placing a through hole pad of the desired size. Then under View/Set Origin with mouse, place the Origin at the center of the pad, (it helps if you zoom in). Now place a second pad at the appropriate distance from the first pad, because you moved the Origin and the first pad is at 0,0, the X, Y readout at the bottom lower left will show you where where the second pad is relative to the first without having to do any math. Now select the first pad with the arrow tool by double clicking on it. Make it pin no. 1, select the second pad, make it pin no.2. These pin numbers correspond to the numbers on the schematics, so, for more complex parts, you need to look at the data sheet and make sure your pin numbering is consistent. Then select the the line tool, pic the yellow line, and draw the outline of the resistor. After drawing, with the arrow tool select the whole thing. Then select Component/Group to make PCB component, then do the Component/Save custom component... give it a name and it's in your library.
Ken
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