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From: George Herold on 13 May 2010 14:46 On May 13, 1:12 pm, John O'Flaherty <quias...(a)yeeha.com> wrote: > On Thu, 13 May 2010 09:45:57 -0700, John Larkin > > <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > >On Thu, 13 May 2010 11:02:58 -0500, John O'Flaherty > ><quias...(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. > > Here's the version with pot and cap, working about as described: Yup, I slapped it onto a white proto-board to see if I was doing something silly. I works fine! George H. > > Version 4 > SHEET 1 880 680 > WIRE 16 48 -80 48 > WIRE 96 48 16 48 > WIRE 304 48 176 48 > WIRE -80 144 -80 128 > WIRE 16 176 16 48 > WIRE 224 176 16 176 > WIRE 304 192 304 48 > WIRE 304 192 288 192 > WIRE 352 192 304 192 > WIRE 480 192 432 192 > WIRE 528 192 480 192 > WIRE 224 208 176 208 > WIRE -80 224 -144 224 > WIRE 96 224 0 224 > WIRE 176 224 176 208 > WIRE 176 224 96 224 > WIRE 480 224 480 192 > WIRE -144 256 -144 224 > WIRE 96 256 96 224 > WIRE 368 272 256 272 > WIRE 256 288 256 272 > WIRE 480 320 480 304 > WIRE 368 352 368 272 > WIRE 96 384 96 336 > WIRE 256 384 256 368 > WIRE 256 384 96 384 > WIRE 96 400 96 384 > WIRE 256 464 96 464 > WIRE 368 464 368 432 > WIRE 368 464 256 464 > WIRE 256 480 256 464 > FLAG -80 144 0 > FLAG 480 320 0 > FLAG -144 336 0 > FLAG 256 480 0 > SYMBOL res 192 32 R90 > WINDOW 0 0 56 VBottom 0 > WINDOW 3 32 56 VTop 0 > SYMATTR InstName R1 > SYMATTR Value 600 > SYMBOL res -64 144 R180 > WINDOW 0 36 76 Left 0 > WINDOW 3 36 40 Left 0 > SYMATTR InstName R2 > SYMATTR Value 200 > SYMBOL res 80 240 R0 > SYMATTR InstName R3 > SYMATTR Value 1200 > SYMBOL res 16 208 R90 > WINDOW 0 0 56 VBottom 0 > WINDOW 3 32 56 VTop 0 > SYMATTR InstName R4 > SYMATTR Value 1200 > SYMBOL res 464 208 R0 > SYMATTR InstName R6 > SYMATTR Value 75 > SYMBOL res 448 176 R90 > WINDOW 0 0 56 VBottom 0 > WINDOW 3 32 56 VTop 0 > SYMATTR InstName R5 > SYMATTR Value 75 > SYMBOL voltage -144 240 R0 > WINDOW 123 24 132 Left 0 > WINDOW 39 0 0 Left 0 > SYMATTR Value2 AC 1 > SYMATTR InstName V2 > SYMATTR Value SINE(0 .5 1e3) > SYMBOL Opamps\\opamp 256 128 R0 > SYMATTR InstName U1 > SYMBOL res 240 272 R0 > SYMATTR InstName R7 > SYMATTR Value 785 > SYMBOL res 240 368 R0 > SYMATTR InstName R8 > SYMATTR Value 215 > SYMBOL voltage 368 336 R0 > WINDOW 123 0 0 Left 0 > WINDOW 39 0 0 Left 0 > SYMATTR InstName V1 > SYMATTR Value 5 > SYMBOL cap 80 400 R0 > SYMATTR InstName C1 > SYMATTR Value 100µ > TEXT 320 40 Left 0 !.lib opamp.sub > TEXT -176 448 Left 0 !.tran 2 > > -- > John
From: John Larkin on 13 May 2010 16:44 On Thu, 13 May 2010 09:20:37 -0700 (PDT), George Herold <gherold(a)teachspin.com> wrote: >On May 13, 12:02�pm, John O'Flaherty <quias...(a)yeeha.com> wrote: >> On Thu, 13 May 2010 11:55:21 -0400, Spehro Pefhany >> >> >> >> >> >> <speffS...(a)interlogDOTyou.knowwhat> wrote: >> >On Thu, 13 May 2010 08:19:22 -0700, John Larkin >> ><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >> >> >>http://electronicdesign.com/article/power/non_inverting_level_shifter... >> >> >>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. >> >> 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. > >Yeah the circuit looked OK to me too. (But I'm often wrong.) I >didn't see an scribbles by B. Pease? Maybe John sent the wrong link? The Pease thing was elsewhere in Electronic Design magazine, The offset circuit is OK for some definitions of OK. The gain and frequency response vary with pot position. And the pot provides up to 10 volts of output offset, with a 5 volt opamp supply. PSRR will suck at low frequencies. And something this obvious shouldn't be in the mag in the first place. John
From: John Larkin on 13 May 2010 16:52 On Thu, 13 May 2010 11:56:44 -0500, John O'Flaherty <quiasmox(a)yeeha.com> wrote: >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? My point was that the gain and the frequency response change as the offset pot is turned. Tacky. My other point is the Electronic Design will publish any old trivial junk to fill in space between the ads. John
From: John Larkin on 13 May 2010 17:26 On Thu, 13 May 2010 14:04:25 -0400, "Michael A. Terrell" <mike.terrell(a)earthlink.net> wrote: > >John Larkin wrote: >> >> Pease just drew another one of his hideous scribbles. >> >> Yes, lots of rusty VWs on his lawn and on the street. >> >> John > > > Don't they have code enforcement out there? That would get you a >huge fine in a lot of states, or even jail time. Some try to claim they >are artists, but still end up in jail. We have street cleaning, once a week on each side of the street, and you'll get a ticket if the car is out. That's really about it. John
From: Jim Thompson on 13 May 2010 18:17
On Thu, 13 May 2010 14:26:11 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Thu, 13 May 2010 14:04:25 -0400, "Michael A. Terrell" ><mike.terrell(a)earthlink.net> wrote: > >> >>John Larkin wrote: >>> >>> Pease just drew another one of his hideous scribbles. >>> >>> Yes, lots of rusty VWs on his lawn and on the street. >>> >>> John >> >> >> Don't they have code enforcement out there? That would get you a >>huge fine in a lot of states, or even jail time. Some try to claim they >>are artists, but still end up in jail. > >We have street cleaning, once a week on each side of the street, and >you'll get a ticket if the car is out. That's really about it. > >John We don't need to park on the street :-) ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy |