I can't take credit for any of that. When I started my first day of work, the engineer who was behind an ambitious amplifier project, Andy Hefley, had just been laid off and came into the tech area to say goodbye to his friends. This was somewhat chilling as I'd interviewed with him and an additional cast of thousands about a month before, before the interviewed-for job had evaporated and before a supervising guy had quit, necessitating his replacement pronto. This required a new set of interviews focusing on my management skills
I did well in those, having not mentioned that I'd headed the family business for a while until we owed so much money to suppliers that I couldn't answer the phone anymore*.
When the amp program that was Andy's baby was shut down, thus as well giving the company a chance to cut a few folks out of the payroll, the parts for the pilot run became freebies for the employees, including about a thousand 2SK364BL, a whole lot of varactor tuning diodes, etc. I was ignorant of a lot of Japanese semiconductors and learned in a hurry.
Brad
*It was an impossible situation, with a lengthy and boring back story about siblings who could not be fired and who were less than suited for their positions. Never again! But good experience.
Good summary, even thought he noise is not a guarantee at audio frequencies (neither are the others) lots of folks have made great use of them since the yield is very high. BTW someone pointed out that the emergency broadcast system for technical reasons will stay on AM and cars may go decades with AM tuners.
There is a dual in the PMBF series but it is two die and the match is not very good, and it's in an even harder package to solder.
EDIT - The high frequency issues might be overstated, I have never had one or two oscillate, I think more than 4 or so in parallel need a little gate damping.
Last edited:
Didn't know about the dual, presumably ones made from adjacent die? Yes, those five or six lead packages are nasty. I guess the last Toshiba dual JFET is one such, about two SK117, and in their questionable wisdom the channels are tied together and brought out on one lead
The 862 provoked me to buy a test socket for screening them. It's not all that easy to position the part but better than soldering leads.
I noticed an LT app note that uses 862s as either source followers or common-source, prefacing an LT op amp. It must have been painful for them to introduce a non-LT part into an app note. But as you pointed out a while back, these JFETs are big, the SK170 being of order the same area as an entire ADI video amp.
Groner found some L necessary in one layout with paralleled devices, but he arranged them in a fairly conventional way on a PCB. Popa used more L than Groner in one of his preamps, I recall a uHy per gate lead. I'm not sure if either author tested to see how low the L could go without problems.
I've had single LSK170s in a bootstrapped source follower oscillate at VHF with typical interconnects hanging off the gate, and a phantom-powered 2SK364 do so when the power and signal were on RG-174 coax and when used as a piezoelectric sensor preamp. In a MC stepup I put an air core coil between the gates of three paralleled grounded-source SK170s and the outside world and didn't have any parasitics, in a folded cascode with Boxall-connected low rbb' bipolars. Sounds good too
But why ? As a load, see from the feedback side witch have an impedance of 22,5 Ohms, it adds a charge of 10 KOhms. So i don't care too much about the internal variation of the output impedance of the TL072.
As a source, it is not supposed to output any signal at, let say, 100Hz. (FC= 0.15Hz, 18db/oct) while any remaining signal is attenuated by 500, as i said.
So what the hell ?
I really want to understand your point, Bob.
For the offset, i agree xith J.C. That the only point i look for with the open loop gain.
Last edited:
Always (e.g. marriage: trade part of private independence for human company)
At least these two are not conflicting parameters.
IMO, it is more a matter of compromise at the techno-economic level (translates into ‘engineering’).
I know you have grown up and gained your experience in hard-core engineering environments but your new area of activity is not such a pure environment , walk carefully (it's only a hint
)You can always e-mail me some specifics, if you think I can be of any remote friendly help
George,
Last edited:
Toshiba and Intel announced 10Tb SSD.
carry on
And next year this will seem "so yesterday".
You're not toking that singularity stuff are you? I'm afraid Kurzweil will pass just like the rest of us.
Hi John,
At my age, 20 KHz is way above my limit of hearing. You have a number of years on all of us, so what was your latest hearing test like?
You're funny.
-Chris
Okay, I bite. You don't like the sound of a tweeter that cuts off at 20 KHz? Or you don't like them from what is on the datasheet? By "cuts off", is this a normal roll-off, or a high order effect that reduces the amplitude very quickly?
At my age, 20 KHz is way above my limit of hearing. You have a number of years on all of us, so what was your latest hearing test like?
You're funny.
-Chris
John,
I'm 59 and can still tell when those very highs are cut off. I'm sure I don't hear as sensitively as i did long ago but I still notice those tones. The actual industrial hearing tests I have normally been given do not test that high,in frequency usually only to make sure you can hear someone else with a certain amount of background noise. I think it is one of those Bose things, if your speakers don't go that high most of the time you would probably not notice, there is no reference to compare it to.But once that sound is there you notice something added. At least that is my impression.
I'm 59 and can still tell when those very highs are cut off. I'm sure I don't hear as sensitively as i did long ago but I still notice those tones. The actual industrial hearing tests I have normally been given do not test that high,in frequency usually only to make sure you can hear someone else with a certain amount of background noise. I think it is one of those Bose things, if your speakers don't go that high most of the time you would probably not notice, there is no reference to compare it to.But once that sound is there you notice something added. At least that is my impression.
But would not the tweeters >20Khz behavior also determine it's behavior
in the sub 20Khz range (compliance).
This could be interpreted (by the brain) as better/more "high end" .
Tweeters that can easily reproduce 20khz+ usually are marketed as
"high compliance" - easiest way to find such tweeters .
OS
- Status
- Not open for further replies.