Hi all!
PRR wrote:
Quote:
The bidirectional audio voltage appears across the FET channel. A bidirectional audio current flows. The ratio of voltage and this current can be controlled by gate voltage.
When you say "gate voltage", do you mean the audio Voltage (AC) or the CV voltage (DC)? So do you mean that it is the CV that changes this "ratio of voltage and the current" by going more nengative or positive? Why is this ratio relevant?
I feel pretty comfortable with the theory and operation of the JFET as a normal amplifier, but I find it really hard to understand the relation between Vgs, Id, Vds and R(JFET) when used as a VCR.
I find it all pretty confusing, especially when some people say that the Vgs doesn't really change neither Vds nor Id, just the relation between them, while others say that an increased gate voltage decreases Id. I think what is confusing is to know if they mean the audio voltage or the CV, when talking about the Vgs.
Does, for example the audio Voltage (Vgs) affect the overall resistance of the channel at all, or is this just the CV?
In the output characterisics graphs, when showing different values of Vgs, are these values of the CV (DC voltage) or the Audio voltage (AC)?
PRR (or anyone=)...I would highly appreciate if you could come up with one of your super clear and mind blowing explinations=) I read the one you wrote about Vari-mu tubes...great stuff!=)
Please! :roll:
What I would like to know is what happens when a audio voltage is applied to the JFET, with the CV voltage constant. How does this change in audio voltage affect the Vds? What happens with Id? And is the change in audio signal going to affect the channel resistance? Or is the channel resistance related to changes in the DC control voltage?
And is the Vgs in the output characterisics graphs demonstrating the CV voltage (DC) or the audio voltage (AC)?
Thank you!!!
Jules [/b]
PRR wrote:
Quote:
The bidirectional audio voltage appears across the FET channel. A bidirectional audio current flows. The ratio of voltage and this current can be controlled by gate voltage.
When you say "gate voltage", do you mean the audio Voltage (AC) or the CV voltage (DC)? So do you mean that it is the CV that changes this "ratio of voltage and the current" by going more nengative or positive? Why is this ratio relevant?
I feel pretty comfortable with the theory and operation of the JFET as a normal amplifier, but I find it really hard to understand the relation between Vgs, Id, Vds and R(JFET) when used as a VCR.
I find it all pretty confusing, especially when some people say that the Vgs doesn't really change neither Vds nor Id, just the relation between them, while others say that an increased gate voltage decreases Id. I think what is confusing is to know if they mean the audio voltage or the CV, when talking about the Vgs.
Does, for example the audio Voltage (Vgs) affect the overall resistance of the channel at all, or is this just the CV?
In the output characterisics graphs, when showing different values of Vgs, are these values of the CV (DC voltage) or the Audio voltage (AC)?
PRR (or anyone=)...I would highly appreciate if you could come up with one of your super clear and mind blowing explinations=) I read the one you wrote about Vari-mu tubes...great stuff!=)
Please! :roll:
What I would like to know is what happens when a audio voltage is applied to the JFET, with the CV voltage constant. How does this change in audio voltage affect the Vds? What happens with Id? And is the change in audio signal going to affect the channel resistance? Or is the channel resistance related to changes in the DC control voltage?
And is the Vgs in the output characterisics graphs demonstrating the CV voltage (DC) or the audio voltage (AC)?
Thank you!!!
Jules [/b]