Electronics Design does it Again!

"Firefox has detected that the server is redirecting the request for this address in a way that will never complete."

Guess they want tracking cookies?

Bob made a mistake? Hard to believe, but can happen to anyone. Does he still have all those mini buses on his lot?

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.

Try this one:

It's Matlin who made the mistake.

Pease just drew another one of his hideous scribbles.

Yes, lots of rusty VWs on his lawn and on the street.

John

Same error message :-(

I don't like tracking cookies.

Sometimes I wonder how many "discussions" he and his wife have about that :-)

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.

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 480 320 480 304 FLAG -80 144 0 FLAG 480 320 0 FLAG 96 416 0 FLAG -144 336 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 96 320 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value 1.5 SYMBOL voltage -144 240 R0 WINDOW 123 24 132 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value SINE(0 .5 1e3) SYMATTR Value2 AC 1 SYMBOL Opamps\\opamp 256 128 R0 SYMATTR InstName U1 TEXT 320 40 Left 0 !.lib opamp.sub TEXT -178 444 Left 0 !.tran 2

Appropriately joining Maxim :-) ...Jim Thompson

Larkin shoots from the hip, and is almost _always_wrong_ :-) ...Jim Thompson

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?

George H.

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?" :-)

Someone can send him a link to that grid paper generator piece of software that was being discussed about a month ago...

---Joel

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

It'll probably be the guy's first patent too... :-)

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.

You did. You left out the pot and the cap.

John

There are two silly articles in the latest ED, the level shifter and a nearly-as-silly Pease Porridge.

John

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?

Here's the version with pot and cap, working about as described:

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

Larkin flails and fails :-) ...Jim Thompson

Pease is getting a wee bit deranged. To see how the student can easily do as he wishes, see the gyrator-based filters on the SED page of my website. ...Jim Thompson

On a sunny day (Thu, 13 May 2010 08:19:22 -0700) it happened John Larkin wrote in :

This is how I level-shifted video: ftp://panteltje.com/pub/mvp.png

I use a LED, and clamp the sync using a diode at the LED voltage (-0.7). The 12 pin PIC does the syn detection, the H and V separation, the line counting, and the video sampling + switching / blanking by driving a 72HC4053 switch. The transistors drive the 75 Ohm cable, gain 2 x Here the peeseebee:

Where did Pease err? ...Jim Thompson