Jfet BOZ

[carpenter]

Originally posted by Nelson Pass
I measured the circuit this afternoon, and it came out mostly
as expected, but the best distortion numbers came from a
16V supply value.

So, this got me thinking: I'm running a 15 volt supply, which--after the Drain resistor--leaves me with 7.5 volts. Does this mean that the Jfet only wants 8 volts DC, or so, on its Drain? This part of amplifier theory always confounds me.

[Zen Mod]

Originally posted by carpenter



So, this got me thinking: I'm running a 15 volt supply, which--after the Drain resistor--leaves me with 7.5 volts. Does this mean that the Jfet only wants 8 volts DC, or so, on its Drain? This part of amplifier theory always confounds me.

look at schematic ;

is it anything familiar ?

ya have eeny weeny jfet , cascoded with eeeny weeny bjt

with ratio of resistors up and down from base of little bjts , you can set different voltages for jfet .

[carpenter]

Originally posted by Zen Mod



look at schematic ;

is it anything familiar ?

ya have eeny weeny jfet , cascoded with eeeny weeny bjt

with ratio of resistors up and down from base of little bjts , you can set different voltages for jfet .

Why, thanks for reminding me, Choky. I've been reading Nelson's works and it slipped my mind that you have material for me to read as well.

I'll get right on it!

[Zen Mod]

Originally posted by carpenter



Why, thanks for reminding me, Choky. I've been reading Nelson's works and it slipped my mind that you have material for me to read as well.

I'll get right on it!

you obviously forgot all pirate things I sent you ?

don't try to read entire books , if you aren't in mood or shape for that ; just find exact problematic in which you are interested , and read about .

find cascodes ....... in scribings of Papa , and in these pirate stuff

[DaveM]

Ah yes. Never forget to cheat when possible. Shortcuts and copying existing work is certainly the quickest way.

[Nelson Pass]

Originally posted by carpenter
So, this got me thinking: I'm running a 15 volt supply, which--after the Drain resistor--leaves me with 7.5 volts. Does this mean that the Jfet only wants 8 volts DC, or so, on its Drain? This part of amplifier theory always confounds me.

Parts have "sweet spots" at which their distortion is at a minimum.
For this JFET with this amount of gain at this bias and with this
load, 8 Vds is the sweet spot for small signals.

For more on this sort of thing, look at the discussion of load lines
in ZV8 and ZV9.

[carpenter]

Thanks, Nelson.

[jupiterjune]

just find exact problematic in which you are interested , and read about

EB's article "The All FET line-amp" has a good writeup on what is basically the same circuit (to start). You might find some useful information there.

JJ

[Zen Mod]

Originally posted by jupiterjune


EB's article "The All FET line-amp" has a good writeup on what is basically the same circuit (to start). You might find some useful information there.

JJ

well said ;

[carpenter]

Originally posted by jupiterjune


EB's article "The All FET line-amp" has a good writeup on what is basically the same circuit (to start). You might find some useful information there.

JJ

Wow.