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From: Joel Koltner on 13 May 2010 12:26 "Jim Thompson" <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote in message news:s89ou5tobmcpditfql3kjes8paq18fpm27(a)4ax.com... > Appropriately joining Maxim :-) It'll probably be the guy's first patent too... :-)
From: Joerg on 13 May 2010 12:38 Joel Koltner wrote: > "John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in > message news:6r5ou5lcgjqv2cg8vbg1831506uqtmod4g(a)4ax.com... >> Such brilliance! How do they keep doing it? > > A lot of graduating BSEEs today never really got that whole thing about > superposition, I suspect? :-) > > Hmm... there might be a good interview question in there somewhere... > "It's clear you can use an op-amp to sum an arbitrary number of inputs > -- both with positive and negative gains -- but why is it that the vast > majority of the time in an 'application example' you see people suggest > only the inverting form?" > > Although I think it was Jim or someone who mentioned that these days > some people don't even get past, "What's the approximate Vbe of any > unremarkable transistor at reasonable currents?" :-) > When I interviewed engineers in the late 90's I found that some of the younger ones were decidedly uncomfortable at transistor-level design. For some reason older ones weren't. Nowadays it's fairly easy to avoid transistor-level. We have blazingly fast opamp, MMIC, muxes and so on. Stuff that was expensive back then and would have come with a huge power consumption penalty. As those who have ever used a HA2540 opamp and touched it after running for an hour will painfully remember. [...] -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: John Larkin on 13 May 2010 12:45 On Thu, 13 May 2010 11:02:58 -0500, John O'Flaherty <quiasmox(a)yeeha.com> wrote: >I see attenuation of 1/2 at the input, gain of 4 (3+1), and >attenuation of 1/2 at the output. LTSpice agrees, unless I made a >mistake. You did. You left out the pot and the cap. John
From: John Larkin on 13 May 2010 12:47 On Thu, 13 May 2010 11:55:21 -0400, Spehro Pefhany <speffSNIP(a)interlogDOTyou.knowwhat> wrote: >On Thu, 13 May 2010 08:19:22 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >> >> >>http://electronicdesign.com/article/power/non_inverting_level_shifter_requires_only_one_op_amp_one_supply_voltage.aspx >> >> >>Such brilliance! How do they keep doing it? >> >>Sarcasm aside, he made a mistake. >> >>And we should take up a collection and buy Pease some grid paper. >> >>John > >The article that links to is by a USSC summer student named Erik, not >Bob Pease. Nominal gain is 0.75 so it's doing more (less?) than level >shifting. There are two silly articles in the latest ED, the level shifter and a nearly-as-silly Pease Porridge. John
From: John O'Flaherty on 13 May 2010 12:56
On Thu, 13 May 2010 09:45:57 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Thu, 13 May 2010 11:02:58 -0500, John O'Flaherty ><quiasmox(a)yeeha.com> wrote: > >>I see attenuation of 1/2 at the input, gain of 4 (3+1), and >>attenuation of 1/2 at the output. LTSpice agrees, unless I made a >>mistake. > > >You did. You left out the pot and the cap. That wasn't a mistake, it was a choice. I believe the intention of the circuit is to have that as an AC ground, that is, as an adjustable reference voltage. Is the fact that the capacitor size wasn't specified in the published circuit the mistake that you meant to point out? -- John |