EL7900

Out of phase with what? The Johnson counter is a divide by three and the bistable is a divide by two - they do change state on the same edges, but not always at the same time. This is just more pretentious bullshit.

But you missed the 11nF capacitors. Don't do much analog design these days?

You've definitely failed to cover yourself with glory here.

-- Bill Sloman, Nijmegen

"Electronic Filter Design Handbook" Arthur B. Williams and Fred J.Taylor

ISBN-10: 0071471715 ISBN-13: 978-0071471718

takes you a little further. There's a more recent edition

-- Bill Sloman, Nijmegen

Sheeeesh! Is Larkin saying he can't design a filter without a handbook or software ?:-)

I was designing (and successfully manufacturing) active filters BEFORE there were simulators. ...Jim Thompson

I could build a doghouse without power tools. But why should I?

Sure. I was designing modems in 1969, with delay-equalized bandpass filters. But I mislaid my slide rule, so I have to use computers now.

On Fri, 07 Sep 2012 16:39:01 -0500, John Fields wrote:

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R9 SYMATTR Value 1k SYMBOL res 128 -320 R0 SYMATTR InstName R10 SYMATTR Value 1k SYMBOL Opamps\\LT1677 0 512 R0 SYMATTR InstName U2 SYMBOL Opamps\\LT1677 0 -400 R0 SYMATTR InstName U3 SYMBOL res -192 96 R90 WINDOW 0 65 62 VBottom 2 WINDOW 3 70 60 VTop 2 SYMATTR InstName R12 SYMATTR Value 1meg SYMBOL Opamps\\LT1677 -384 48 R0 SYMATTR InstName U4 SYMBOL cap -368 0 R90 WINDOW 0 -32 36 VBottom 2 WINDOW 3 -31 29 VTop 2 SYMATTR InstName C6 SYMATTR Value 220nF SYMBOL res -336 -96 R90 WINDOW 0 -32 64 VBottom 2 WINDOW 3 -32 67 VTop 2 SYMATTR InstName R13 SYMATTR Value 1meg SYMBOL Opamps\\LT1677 -384 528 R0 SYMATTR InstName U5 SYMBOL cap -352 464 R90 WINDOW 0 -34 37 VBottom 2 WINDOW 3 -36 30 VTop 2 SYMATTR InstName C9 SYMATTR Value 220nF SYMBOL res -336 368 R90 WINDOW 0 -47 62 VBottom 2 WINDOW 3 -37 62 VTop 2 SYMATTR InstName R14 SYMATTR Value 1meg SYMBOL Opamps\\LT1677 -384 -384 R0 SYMATTR InstName U6 SYMBOL cap -352 -448 R90 WINDOW 0 -37 34 VBottom 2 WINDOW 3 -33 30 VTop 2 SYMATTR InstName C10 SYMATTR Value 220nF SYMBOL res -496 368 R90 WINDOW 0 -30 51 VBottom 2 WINDOW 3 -29 51 VTop 2 SYMATTR InstName R17 SYMATTR Value 51k SYMBOL res -496 -448 R90 WINDOW 0 -37 62 VBottom 2 WINDOW 3 -36 63 VTop 2 SYMATTR InstName R18 SYMATTR Value 51k SYMBOL res -336 -544 R90 WINDOW 0 -47 62 VBottom 2 WINDOW 3 -37 62 VTop 2 SYMATTR InstName R19 SYMATTR Value 1meg SYMBOL voltage -2448 176 R0 WINDOW 0 111 105 Left 2 WINDOW 3 24 96 Invisible 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V3 SYMATTR Value 3 SYMBOL voltage -2352 288 R180 WINDOW 0 53 7 Left 2 WINDOW 3 24 16 Invisible 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V2 SYMATTR Value 3 SYMBOL Digital\\dflop -2000 48 R0 WINDOW 3 8 168 Invisible 2 SYMATTR Value trise 1e-7 tfall 1e-7 vhigh 3 vlow -3 SYMATTR InstName A6 TEXT -2424 360 Left 2 !.tran 0 1s 0 1ms startup uic

I have that. Good book. The filter "designs" are mainly looking up prototypes in the tables and normalizing them, which is fine. I wrote a PowerBasic program to do the normalization math for LC filters, which helps when juggling to hit available values.

He has some good all-pass stuff.

But I still prefer to use a filter design program when I can, which is almost always nowadays. Saves a lot of typing.

Williams and Taylor put me onto the Sallen and Keys with some gain, which does make the capacitor values quite a bit more flexible.

It does cover more variations of filters than most. I found the "equi- ripple approximations to linear-phase filters" unexpectedly handy about twenty years ago - the classical version had too much gain at the front end, but the equi-ripple approximation came out a lot more practicable.

-- Bill Sloman, Nijmegen

I was wondering what that was for.

Without the divide-by-2, the RC glitch reset is safe. Only one flop gets set on the first clock, the first flop of the ring counter. And if it misses, it will fire on the next clock.

The filters still aren't flat, so if you change the clock frequency the amplitude changes a lot. With two opamps, you could do a 4-pole Butterworth or Chebychev filter and get nicer sine waves, flat over an octave maybe. That 3rd harmonic is the killer.

There's probably some resistive mixing that could be done from the available logic outputs that would reduce the 3rd harmonic.

Just have the clear pass through the flop thresholds at the same time as a clock hits. Don't need a timing diagram to envision that.

But if you dump the div-2 flipflop, there is no hazard. The first flop of the Johnson counter either sets, or it doesn't.

It sure as hell ain't the only topology that can give you that.

Gawd damn, can you even read? JT has to directly control them.

Overly addicted to a power tool to do what you can't.

?-(

Got an ISBN for that? If you respect it, it goes on my to read list.

?-)

You are doing much better. Staying off the people and on the electronics.

How about, because they are not necessary and can be expensive? Very especially if you do not know to either; how to value shop, or use possibly expensive tools. (Or possessively worse get crippled by using them: e. g. SPICE)

No, you can't have any of mine. I still know how to use them.

?-)

OK, what others?

You think he designs around ideal opamps? I can't buy them in SOT23 packages.

I'm an engineer. I design a lot of electronics. Given the choice of doing things the hard way, or doing them the easy way, I cheat and pick the easy one. I'm not sure I can still do long division.

I used to design filters by hand. I used to lay out PCBs with tape and mylar. Neither was a lot of fun.

Latest laser driver board; did the layout on this one meself!

Real Men love power tools. How do you drill holes? Use an old brace-and-bit? One of those hand-crank bevel gear drills?

Very

Spice saves a lot of time, sometimes. I just ran a bunch of sims on the LTM8023 switcher module, looking for sub-cycle oscillations. The LTC macromodel isn't super good, and the sim doesn't quite match reality, but it was educational. Looks like we need to stock up on polymer aluminum caps.

Well, I have a couple of HP35s that still work. And I do a lot of math in my head, which I still know how to use.

Gosh, do you really think so?

'Real Men' are craftsmen with whatever tools they can find to use. Some of the finest things ever made were done with the simplest of tools.

As far as a drill? I have several drill presses, including a 'Cameron Precision'. At least a half dozen cordless drills, air drills, Dremmel, and their clones and I had a brace & bit that was very handy for drilling holes in power poles where there was no power to run a 1/2" power drill. You can't get through one hole with most cordless drills when drilling that treated wood. You also need special drills to cut the wood, and not burn up.

I have spent hours with files to make metal parts, when a milling machine wasn't available or to repair damaged power tools that could have been used to make that part. I just repaired the embedded controller for a pipe bender for a local factory. A replacement was over $700 and they would have been down over a month, waiting for the replacement from the OEM in Italy. they can't ship any product with that one machine down. The repair costs were under $7. There is no documentation available, other than the mechanical parts & a list of the modules. It uses a VFD a three phase motor and a Rabbit Semiconductor module, plus their custom display & keyboard. Their part is poorly designed, and was damaged because some idiot put a Ni-Cad battery on the interface board where it ate the traces off the board when it leaked. The first board worked for eight years. A brand new replacement only lasted 13 months. Like a lot of computer motherboards in the 286-486 days, it was designed to self distract.