If it ran cold, nobody told me. There was basically no thermal conduction from the DIP opamps to the hand-wired ceramic slab. Gain was unity, so 2nd stage (room temp) noise would overpower even a zero-noise input stage.
It had terrible birdies from fluorescent light ballasts, AM stations, everything. The spectrum was a picket fence of spikes above the already terrible noise floor.
I wonder if an OPA627 will work at cryo temps.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Fat chance. Certain MOSFETs do seem to work in liquid helium
and I thought that I remembered someone publishing the claim that some RCA pure CMOS op-amp did, but google doesn't throw it up.
-- Bill Sloman, Sydney
If it ran cold, nobody told me. There was basically no thermal conduction from the DIP opamps to the hand-wired ceramic slab. Gain was unity, so 2nd stage (room temp) noise would overpower even a zero-noise input stage.
It had terrible birdies from fluorescent light ballasts, AM stations, everything. The spectrum was a picket fence of spikes above the already terrible noise floor.
I wonder if an OPA627 will work at cryo temps.
-- John Larkin Highland Technology, Inc lunatic fringe electronics =========================================================== Did you look down the bore of the vacuum chamber with the trap assembly out? Maybe it was simply inside a cold tube so the radiation background would have been 77 K or so and the trap itself would have gradually cooled down and the preamp would have cooled some, but it wasn't actually touching, or maybe that was part of the "proprietary" stuff McIver was deliberately misleading on. I had my hands on/in several Nicolet systems over the years and knew most of the EE's there, and talked with some Bruker engineers about their electronics a few times, but the IonSpec was always considered the low end, cheap, kind-of-works system and luckily I never actually touched one :-). I had high hopes when Varian bought them, especially when I found out that you were consulting with them, but as you described that didn't work out. The Nicolet division went through about four owners and wound up at ThermoFisher where it was basically shut down because the Orbitrap system they came out with didn't need a magnet and could compete with the mid range FTMS systems (say 4.7 to 7 T) on mass resolving power which was always the one thing an FTMS did the best, along with mass measurement accuracy. I think the Thermo system was pulled within a year +/- of the Varian shutdown. Nowadays only Bruker still sells general purpose mid and high end systems, and the Magnet Lab and PNNL compete for bragging rights at the $$$$ high field end. I think the Magnet Lab has a 21 T system and PNNL a 14 or 15 T system, but I think the PNNL system was running first so for awhile they trumped the Magnet Lab's 11 T or whatever :-). Sorry, it's just kind of run reminiscing.
My theory is that superconductive magnets are just too expensive for most analytical science. MRI works because they can charge a thousand dollars an hour for that.
I was also deeply involved with the Imago atom probe, eventually acquired by Cameca. I got a lot of zero-value stock.
Science is fun, but not often profitable.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Could that be CA3130? It might have gain, but the currents get all wacky when cold. Biasing is done with zener and forward diodes and sources are loaded with bipolars.
Possibly there were silicon-on-sapphire specials, NASA would know...
Sure you're not thinking of the 3100 or 3140? IIRC the 3130 was all-MOS. ( My dim recollection is that it was all NMOS and not CMOS.)
Back around 1980, the BiMOS CA3100 had about the best intermod performance of any op amp.
Cheers
Phil Hobbs
get
rains) are loaded
(My dim recollection is that it was all NMOS and not CMOS.)
I'm looking at the 1976 RCA Integrated Circuits manual. Same info here:
The outputs of the CA3140 were bipolar, those of the CA3130 were MOS, but CMOS processes didn't include any resistors back then. So, the CA3130 used the same BICMOS process as CA3140, with internal diodes and NPN drain loads (I just checked: PMOS inputs, the negative terminal is drai n loads, not the source - and level translator Q11 is another NPN).
All the bias resistances are presumably base resistors of the bipolar proce ss. They'd change value markedly with temperature.
Venture capitalists seem to work on the prionciple that one profitable start-up pays for a lot of duds, with quite a bit left over.
-- Bill Sloman, Sydney
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