What's All This Femtoampere Stuff, Anyhow?

[@analogplanet9675]

Absolutely Love these videos and Bob Pease, but I'm skeptical about detecting individual cosmic rays with a charge amp. I've played with femto-amp parts like LMP7721 in various well guarded and shielded situations and never noticed even the slightest susceptibility to radiation, except for the low frequency "ion chamber" leakage effect due to intense fluxes from radioactive sources. Would be cool though....

[@christianweagle6253]

Maybe National, err, I mean, TI could task an intern with tracking down the originals of these videos and re-encoding them modern-style. Bob Pease was almost a national resource; these presentations (yes, with their technical flaws) should be in a museum.

[@HarjitSingh-be7gb]

The production site was in Malacca MALAYSIA not Indonesia..I implemented this solution into production back in the 90s

[@Tadesan]

He's from sales.

[@michaelmolter6180]

13:09 is where the actual discussion starts.

[@Tadesan]

It's so cute that Bob didn't understand Teflon is a dielectric. A metal coat hanger would have been better. I bet Bob told the engineers to use a Teflon rod. Notice he says that they solved the problem.

[@jonahansen]

"We never saw any really bad parts" - ha ha.

[@thewii552]

RIP bob

[@KelvinLeUT]

does anyone notice how the op amp low pass filter at 2:05 is drawn incorrectly. Look at the positive and negative terminals.

[@faidularcs]

You are wrong

[@k7iq]

Yep it sure is. Wrong input polarity that's not going to be too good of an amplifier buffer

[@zanekaminski]

I enjoyed the Agilent plug. I would love a 54642D scope, but they're still a bit pricey (~$1000 USD) and they only have two analog channels. My friend picked up a lower-end 54622D for $100, which has the same user interface but only samples at 200 MSa/s, which isn't fast enough for all of my work. The newer MSO6000 series has four channels and greater bandwidth and sample rate, but they have kept their value very well and are even further out of my budget, at $5000+ for a model with fair specs.

[@humgar]

I love the 54600 series. The design is very intuitive and it's usually problem free. 54640 series is a different beast that has a quirk that the ADC runs too hot and the hybrid will eventually fail if there is not a custom fan blowing at it directly. It's worth around $3.8k so if you can get it at $1k, it's a steal. Chances are recyclers are willing to sell it to you at that price but you are on your own once the 30 or 60 days is over. You can do the fan mod yourself with the instructions here: wonghoi.humgar.com/blog/2016/07/24/agilent-54641d-fan-mod/

[@advancedmicrosystems4658]

@@humgar just picked up an 54642D with complete probes and SMD clips for 350€. 3.8k is a joke...I mean Keysight official Ebay shop will sell you a 1Ghz 4ch 3000X for around 6k, so charging more than half of that for a 20 year old unit with just 2 ch and CRT is ridiculous.

[@anonanon5146]

"What is metrology, daddy?"

[@definitionofis]

I heard here, Bob Pease died in a car crash: theamphour com/2011/06/20/the-amp-hour-48-posthumous-pease-porridge/

[@k7iq]

Yes, unfortunately. And I think it was returning from his friend, Jim William's funeral. Another great designer

[@gerryjamesedwards1227]

Yes, such a sad coincidence. We had to say goodbye to two of the giants of analog electronics in the space of a few days.

[@gerryjamesedwards1227]

I bet you could have learned a hell of a lot, as well as had a good laugh, if you could have earwigged on Bob and Jim shooting the breeze.

[@GodzillaGoesGaga]

@@k7iq Yes, he was returning from Jim Williams Wake at Mountain Winery in Saratoga, CA from what I recall. I knew a few guys who were there at the wake.

[@Tadesan]

@@k7iq oh goodness that's a sad coincidence.

[@MNMTX]

who needs a cosmic ray detector?