KBK said:
You may chose to live without physics (or any other scientific discipline) as a way to understand and predict the reality, as much as you may chose to return to the caves and live according to your senses and subjective feelings.
I don't, as I find caves to cold and stinky to my (subjective) taste.
Good luck and stay warm.
V-types would also be my choice, but as I mentioned before suggested configuration (see earlier posts) is merely for other types of JFets with less current margin.
Any useful comments/suggestions on the servo, John, Joshua, anyone?
Any useful comments/suggestions on the servo, John, Joshua, anyone?
syn08 said:
Physics is but an attempt to understand the world and the universe in which we live.
Joshua_G said:
Joshua_G said:
Joshua
We have all seen these, and what is your conclusion if you compare these with the circuits that courage posted?
Could you give courage an advice regarding his servo?
That's what he's asking for.
Stinius
Joshua_G said:
It's actually an attempt to describe the analog world in numerical form. The question always comes down to whether or not all the variables were captured.
As far as servos are concerned, there are only a few approaches, but numerous ways to connect the servo output(s) back into the preamp or power amp.
There are two types of servo, Common Mode, and Differential Mode, and they measure different things. Common Mode compares the AVERAGE DC offset of the 2 outputs to ground and forces the two outputs close to ground. Differential Mode offset compares the 2 outputs and forces them to be nearer each other. This is how I generally do it.
Others might separately take each side of the circuit and force it to be close to ground independently. Both approaches take about the same number of parts.
The details always drive me crazy, and I often get the phases wrong at first.
If you look at the JC-2 schematic in post 10520, you will see an example of a servo hookup, however with one resistor too many. I will report back when I remember which one (in the servo) should be removed.
There are two types of servo, Common Mode, and Differential Mode, and they measure different things. Common Mode compares the AVERAGE DC offset of the 2 outputs to ground and forces the two outputs close to ground. Differential Mode offset compares the 2 outputs and forces them to be nearer each other. This is how I generally do it.
Others might separately take each side of the circuit and force it to be close to ground independently. Both approaches take about the same number of parts.
The details always drive me crazy, and I often get the phases wrong at first.
If you look at the JC-2 schematic in post 10520, you will see an example of a servo hookup, however with one resistor too many. I will report back when I remember which one (in the servo) should be removed.
John,
I have taken notice of the earlier posting with the JC-2 schematic + servo. However this configuration is quite different from BT "look alike" in terms of components and servo return points.
The possible options for the servo return points are:
1. at the JFets sources
2. at the Mosfets sources
3. at the Mosfets gates
In the attached schematic the choice for servo return point at the Mosfets sources has been made, which to me gives the least instability problems and servos are according to what you described in your latest post.
As always comments/suggestions are welcome.
I have taken notice of the earlier posting with the JC-2 schematic + servo. However this configuration is quite different from BT "look alike" in terms of components and servo return points.
The possible options for the servo return points are:
1. at the JFets sources
2. at the Mosfets sources
3. at the Mosfets gates
In the attached schematic the choice for servo return point at the Mosfets sources has been made, which to me gives the least instability problems and servos are according to what you described in your latest post.
As always comments/suggestions are welcome.
Attachments
Looks pretty good, Courage. I like the servos.
However, could you reduce the 47 ohm bias resistors to 10ohms or so. It just won't work well with high value resistors and these jfets.
However, could you reduce the 47 ohm bias resistors to 10ohms or so. It just won't work well with high value resistors and these jfets.
Yeah.
I agree with John.
Looks good.
.... and Very Curlish a circuit 😎
----------------
* curlish; to be curlish
something that is very similar to the methods of John Curl, amplifier designer,
that lived in from the middle of 20th century to the middle of 21th century
I agree with John.
Looks good.
.... and Very Curlish a circuit 😎
----------------
* curlish; to be curlish
something that is very similar to the methods of John Curl, amplifier designer,
that lived in from the middle of 20th century to the middle of 21th century
My 'signature' is the flower pattern. I remember back in 1974 showing my future wife what I did. She played the violin at the Institute, but I just seemed to 'hang around'. I showed her my schematics and presented them as a pattern, rather than just a function. I suggested to her that it looked like a flower pattern, at the time, or 4 quadrant symmetry.
I don't think I will live that long, I am starting to feel 2/3 of a century old, truly. That's why you 'critics' should stop picking on me.
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