You should be able to use two parallel BF862, xSK170, or similar JFETs, per half of a 2SK146 and get very close to the original. Edit: was too slow.
I've had obsolescence on my mind of late. I no sooner tell a contract manufacturer how much I hate single-sourced components than the options evaporate.
And I really should have said discontinuance, not obsolescence. The latter means something is no longer desired, which is not the case most of the time with electronic parts --- unless it applies to the decision-makers at the parts houses.
http://www.richardhess.com/manuals/Amber3501.pdf
The rest of the manual (on a quick look) is also not bad for theory of operation.
I have a reputation for finding a new part and everyone here telling me it will soon be EOL based on my past history. Now I just buy them all.
Does Nelson know you talk about him like that 😛
(sorry couldn't resist. It is friday after all) 🙂
why resurrect these circuits - recent op amps have much better output stages with faster, better matched complementary Q
show discrete fet input with something from only the last 20 years, please
yes you don't have as many options today to cut off/bypass the input in the following op amp - but many can be had so many times faster that you wouldn't need to to exceed a 5534 composite circuit
show discrete fet input with something from only the last 20 years, please
yes you don't have as many options today to cut off/bypass the input in the following op amp - but many can be had so many times faster that you wouldn't need to to exceed a 5534 composite circuit
awkward wording on my part - I was trying to ask why don't people show discrete fet inputs with modern op amp following them
trying to point out that the modern op could be selected to be so much faster than a 5543 with disabled input replaced by discrete fets that you could still compensate the discrete fet+series modern op amp multiloop to give a faster composite amp than the fet+5534 despite not being able to bypass the modern part's input stage, having to accept the "extra" stage in series
get the discrete fet noise - and modern op amp output
trying to point out that the modern op could be selected to be so much faster than a 5543 with disabled input replaced by discrete fets that you could still compensate the discrete fet+series modern op amp multiloop to give a faster composite amp than the fet+5534 despite not being able to bypass the modern part's input stage, having to accept the "extra" stage in series
get the discrete fet noise - and modern op amp output
I meant my comment originally to mildly take a jab at the 5532 haters. Of course, updating these old circuits with modern, high speed opamps would be prudent, even without bypassing the input pair. The biggest benefit I could imagine is stability (distortion/etc has got to be beyond audible).
Certainly provides me with some entertainment 🙂 in my retirement.
As Bob Cordell documented in the lsk489 app note. More circuits for me to try out. pcbway has the $13 per 100x100mm pcb special for 2 layer, how cheap is that to make some toys to play with!!
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