You can raise the values of R1 and R2 to lower the current. To keep the
same gain you would also raise the values of R5 and R6
Make no mistake, there is NO chance they are real...why people keep buying this crap is beyond me.
Russellc
Again, you are wasting your time with the Chinese J-fets. Throw them away and dont torture your PCB. They will not be "maybe good" they will be fake. Once installed, amp will not work properly and you will have a million questions wondering why. Just get proper parts from Ha or Spencer. There are no other choices, until Linear really lets them go to market.....WoW! looks like they just hit DIY store!
Russellc
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now that we have JFETS in the store, could someone comment on what grades would work best for the various popular amps? ? I think "Papa" mentioned "B and C" for most of his amps but aren't sure I remember correctly.
8 pieces of LSK170 ULTRA LOW NOISE SINGLE N-CHANNEL JFET - Parts
8 pieces of LSJ74 ULTRA LOW NOISE SINGLE P-CHANNEL JFET - Parts
There are links to their spec sheets
8 pieces of LSK170 ULTRA LOW NOISE SINGLE N-CHANNEL JFET - Parts
8 pieces of LSJ74 ULTRA LOW NOISE SINGLE P-CHANNEL JFET - Parts
There are links to their spec sheets
Thanks for your responses AndrewT and Nelson. I'll get simming and explore those recommendations.
It's beyond my understanding at the moment, but I do wonder if I can cascode the jfets to reduce voltage across (and thus dissipation) and take advantage of the higher transconductance at a higher Idss somehow... If only I actually knew what I was doing!
Good news on the Linear SJ74's becoming available - but wheres the fun in just dropping a part in when I can struggle away learning how to utilize a different part?
It's beyond my understanding at the moment, but I do wonder if I can cascode the jfets to reduce voltage across (and thus dissipation) and take advantage of the higher transconductance at a higher Idss somehow... If only I actually knew what I was doing!
Good news on the Linear SJ74's becoming available - but wheres the fun in just dropping a part in when I can struggle away learning how to utilize a different part?
Matched pairs are inevitable but we aren't the fastest moving guys around.
Here's what Papa Pass said:
The B through D and most of the A would not be a problem
for the ACA, and a slight adjustment would allow down to the
2.5 mA figure without problems.
Most of my projects would want a B or C grade as most desirable,
but it’s not a big deal.
Here's what Papa Pass said:
The B through D and most of the A would not be a problem
for the ACA, and a slight adjustment would allow down to the
2.5 mA figure without problems.
Most of my projects would want a B or C grade as most desirable,
but it’s not a big deal.
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not likely
they're too wimpy , in xconductance department
you would need (typically) 3 of them in parallel instead of one Toshiba
even then you need to adjust source resistance to have sum current of 8mA , which would heavily influence gain of stage
wait for Store , supposedly they're soon to have them again
they're too wimpy , in xconductance department
you would need (typically) 3 of them in parallel instead of one Toshiba
even then you need to adjust source resistance to have sum current of 8mA , which would heavily influence gain of stage
wait for Store , supposedly they're soon to have them again
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