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Thanks for the link Chris, The all-pass network certainly uses a lot of op-amps. I'm not sure what a DSotM is? But I used the phase sequence filter as part of the phase shifter in this lock-in.

Only good from 3 Hz to 3kHz.

George H.

Thanks for the link Chris, The all-pass network certainly uses a lot of op-amps. I'm not sure what a DSotM is? But I used the phase sequence filter as part of the phase shifter in this lock-in.

Only good from 3 Hz to 3kHz.

George H.

Thanks for your link; interesting.

Dark Side of the Moon: 19th para in

It was a frequency translator (shifter) with the 'local oscillator' set to about 1 Hz, and the output (shifted) signal mixed with the input signal. Some liken the effect to that of a Leslie speaker (e.g. which used to be available as a .pdf), but the latter is a lot more complicated. Harald Bode had at least one patent for a 'barber pole' phasing scheme using the same principle and some have drawn comparisons with the so-called 'Shepard Tone' One regular correspondent to this NG is on record as saying 'Some foul noises are possible if you mix the original and the shifted sounds' - and as the editor of a popular British magazine has written: one man's ultimate guitar tone is the next man's angle grinder!

As you say, a polyphase network of reasonable complexity is good for 3 octaves, such as the SSB speech band 300 Hz to 2.4 kHz or, at a stretch, up to 4.8 kHz. Some claim to have achieved good sideband suppression even up to

9.6 kHz. The way forward nowadays must surely be DSP, wherein increased complexity becomes little more than duplication, and a simple implementation is described in ... but that makes me sound like a code writer.

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Thanks again Chris, I'm afraid I'm not much of an audio guy. Though lots of the circuits I build work in the audio range. I remeber mentioning to a guitar playing friend that I was using a diode ring modulator as part of a capacitance sensor. He started talking about guitar effects and I had no idea what he was refering to. I was born in '58 so DSotM is somting I know.. at the time I had no interest in how it was made...still love'd it.

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I must be more lucky than smart. I never tried to push anything in the lockin design. Honestly it was my bosses idea and I never thought it would be a big seller. (not the first time I've been wrong.) IIRC I used eight stages of R/C's. I was more worried about the 3Hz part of the spectrum at the time. The idea was to span both sides of

60Hz. I'm not sure how to measure sideband suppression, but I would think that 30 Hz to 30kHz would be doable. I could reduce either the C or the R. It's interesting that the circuit presents vastly different impedances as a function of frequency to whatever is driving it. I used good polypro capacitors.

George H.

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Version 4 SHEET 1 1056 1048 WIRE 496 -448 368 -448 WIRE 368 -416 368 -448 WIRE 496 -416 496 -448 WIRE 208 -336 176 -336 WIRE 624 -336 560 -336 WIRE 800 -336 704 -336 WIRE 176 -272 -224 -272 WIRE 368 -272 368 -336 WIRE 368 -272 176 -272 WIRE 416 -272 368 -272 WIRE 688 -272 416 -272 WIRE 784 -272 688 -272 WIRE 560 -160 560 -336 WIRE -16 -144 -96 -144 WIRE 96 -144 96 -336 WIRE 96 -144 64 -144 WIRE 688 -128 688 -272 WIRE 176 -112 176 -272 WIRE 560 -112 560 -160 WIRE 656 -112 560 -112 WIRE 96 -96 96 -144 WIRE 144 -96 96 -96 WIRE 800 -96 800 -336 WIRE 800 -96 720 -96 WIRE 896 -96 800 -96 WIRE 976 -96 976 -144 WIRE 288 -80 288 -336 WIRE 288 -80 208 -80 WIRE 352 -80 352 -96 WIRE 352 -80 288 -80 WIRE 480 -80 480 -160 WIRE 480 -80 352 -80 WIRE 608 -80 560 -80 WIRE 656 -80 608 -80 WIRE 128 -64 64 -64 WIRE 144 -64 128 -64 WIRE 480 -64 480 -80 WIRE 560 -64 560 -80 WIRE -96 -32 -96 -144 WIRE -16 -32 -96 -32 WIRE 64 -32 64 -64 WIRE 976 -32 976 -96 WIRE 128 -16 128 -64 WIRE 176 -16 176 -48 WIRE 368 -16 176 -16 WIRE 480 16 480 -64 WIRE 496 16 480 16 WIRE 560 16 560 -64 WIRE 688 16 688 -64 WIRE 864 16 688 16 WIRE 608 48 608 -80 WIRE 608 48 560 48 WIRE -96 64 -96 -32 WIRE -16 64 -96 64 WIRE 64 64 64 -32 WIRE 64 64 48 64 WIRE 128 80 128 48 WIRE 976 96 976 48 WIRE 416 112 416 -272 WIRE 416 112 224 112 WIRE 560 144 560 112 WIRE 128 160 80 160 WIRE -352 176 -448 176 WIRE -96 176 -96 64 WIRE -96 176 -272 176 WIRE 80 256 80 240 WIRE 560 256 560 224 WIRE 832 256 768 256 WIRE -224 272 -224 -272 WIRE -224 272 -304 272 WIRE -304 288 -304 272 WIRE 256 288 176 288 WIRE -448 304 -448 176 WIRE -336 304 -448 304 WIRE 416 304 416 272 WIRE 416 304 400 304 WIRE -96 320 -96 176 WIRE -96 320 -272 320 WIRE 400 320 400 304 WIRE 512 320 400 320 WIRE 688 320 688 256 WIRE 688 320 592 320 WIRE 784 320 784 -272 WIRE 784 320 752 320 WIRE -336 336 -368 336 WIRE -96 336 -96 320 WIRE -32 336 -96 336 WIRE 96 336 96 288 WIRE 96 336 48 336 WIRE -448 352 -448 304 WIRE 224 352 224 112 WIRE 752 352 752 320 WIRE 96 368 96 336 WIRE 192 368 96 368 WIRE 688 368 688 320 WIRE 720 368 688 368 WIRE 336 384 336 288 WIRE 336 384 256 384 WIRE 400 384 400 320 WIRE 400 384 336 384 WIRE 832 384 832 256 WIRE 832 384 784 384 WIRE 896 384 832 384 WIRE 976 384 976 304 WIRE 192 400 176 400 WIRE 720 400 704 400 WIRE -304 416 -304 352 WIRE -176 416 -304 416 WIRE -96 416 -96 336 WIRE 0 416 -96 416 WIRE 400 416 400 384 WIRE 512 416 480 416 WIRE 624 416 592 416 WIRE 688 416 624 416 WIRE 704 416 704 400 WIRE 704 416 688 416 WIRE -448 464 -448 432 WIRE 688 464 688 416 WIRE 80 480 80 416 WIRE 144 480 80 480 WIRE 176 480 176 400 WIRE 176 480 144 480 WIRE 752 480 752 416 WIRE 864 480 864 16 WIRE 864 480 752 480 WIRE 976 480 976 384 WIRE 224 496 224 416 WIRE 288 496 224 496 WIRE -96 512 -96 416 WIRE 16 512 -96 512 WIRE 80 512 80 480 WIRE 144 512 144 480 WIRE 400 544 400 416 WIRE 624 544 624 416 WIRE 624 544 464 544 WIRE 688 560 688 528 WIRE -448 592 -448 544 WIRE -368 592 -368 336 WIRE -368 592 -448 592 WIRE 976 592 976 560 WIRE -448 624 -448 592 WIRE 32 640 16 640 WIRE 144 640 144 576 WIRE 144 640 112 640 WIRE 16 672 16 640 WIRE 688 672 688 640 WIRE 16 800 16 752 WIRE 688 800 688 752 WIRE -176 848 -176 416 WIRE 288 848 288 496 WIRE 288 848 -176 848 WIRE 368 848 368 -16 WIRE 368 848 288 848 WIRE 864 848 864 480 WIRE 864 848 368 848 WIRE 896 848 864 848 WIRE 896 880 896 848 WIRE 896 1008 896 960 =46LAG -448 624 0 =46LAG 80 256 0 =46LAG 16 800 0 =46LAG 560 256 0 =46LAG 688 800 0 =46LAG 976 96 0 =46LAG 976 592 0 =46LAG 896 1008 0 =46LAG 496 -416 0 =46LAG 976 -144 +45deg =46LAG 976 304 -45deg =46LAG 352 -96 +deg1 =46LAG 416 272 -deg1 SYMBOL Opamps\\\\LT1028 -304 256 R0 SYMATTR InstName U1 SYMBOL Opamps\\\\LT1028 176 -144 R0 SYMATTR InstName U2 SYMBOL Opamps\\\\LT1028 688 -160 R0 SYMATTR InstName U3 SYMBOL Opamps\\\\LT1028 224 320 R0 SYMATTR InstName U4 SYMBOL Opamps\\\\LT1028 752 320 R0 SYMATTR InstName U5 SYMBOL voltage -448 448 R0 WINDOW 123 24 132 Left 0 WINDOW 39 24 160 Left 0 SYMATTR Value2 AC 1 0 SYMATTR SpiceLine Rser=3D100 Cpar=3D20p SYMATTR InstName V1 SYMATTR Value SINE(0 1 20) SYMBOL res -256 160 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R1 SYMATTR Value 10k SYMBOL res 192 -352 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R2 SYMATTR Value 100k SYMBOL res 304 -352 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R3 SYMATTR Value 5.6k SYMBOL res 80 -160 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R4 SYMATTR Value 22k SYMBOL res 80 -48 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R5 SYMATTR Value 56k SYMBOL res 64 320 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R6 SYMATTR Value 22k SYMBOL res 96 400 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R7 SYMATTR Value 39k SYMBOL res 192 272 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R8 SYMATTR Value 100k SYMBOL res 352 272 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R9 SYMATTR Value 5.6k SYMBOL res 576 -176 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R10 SYMATTR Value 12k SYMBOL res 576 -80 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R11 SYMATTR Value 47k SYMBOL res 608 304 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R12 SYMATTR Value 12k SYMBOL res 608 400 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R13 SYMATTR Value 3.9k SYMBOL res 720 -352 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R14 SYMATTR Value 47k SYMBOL res 784 240 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R15 SYMATTR Value 47k SYMBOL res 112 64 R0 SYMATTR InstName R16 SYMATTR Value 47k SYMBOL res 64 144 R0 SYMATTR InstName R17 SYMATTR Value 4.7k SYMBOL res 0 656 R0 SYMATTR InstName R18 SYMATTR Value 2.0k SYMBOL res 128 624 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R19 SYMATTR Value 33k SYMBOL res 672 656 R0 SYMATTR InstName R20 SYMATTR Value 1.5k SYMBOL res 672 544 R0 SYMATTR InstName R21 SYMATTR Value 22k SYMBOL res 544 128 R0 SYMATTR InstName R22 SYMATTR Value 22k SYMBOL cap 112 -16 R0 SYMATTR InstName C1 SYMATTR Value 1n SYMBOL cap 544 48 R0 SYMATTR InstName C2 SYMATTR Value 100n SYMBOL cap 128 512 R0 SYMATTR InstName C3 SYMATTR Value 27n SYMBOL cap 672 464 R0 SYMATTR InstName C4 SYMATTR Value 470p SYMBOL cap 560 0 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C5 SYMATTR Value 100n SYMBOL cap 48 48 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C6 SYMATTR Value 1n SYMBOL cap 80 496 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C7 SYMATTR Value 27n SYMBOL res 496 400 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R23 SYMATTR Value 47k SYMBOL cap 464 528 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C8 SYMATTR Value 470p SYMBOL res 992 -112 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R24 SYMATTR Value 2k SYMBOL res 992 368 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R25 SYMATTR Value 2k SYMBOL res 960 -48 R0 SYMATTR InstName R26 SYMATTR Value 100k SYMBOL res 960 464 R0 SYMATTR InstName R27 SYMATTR Value 100k SYMBOL voltage 368 -320 R180 WINDOW 0 24 104 Left 0 WINDOW 3 24 16 Left 0 WINDOW 123 0 0 Left 0 WINDOW 39 24 76 Left 0 SYMATTR InstName V3 SYMATTR Value 15 SYMATTR SpiceLine Rser=3D0.1 SYMBOL voltage 896 976 R180 WINDOW 0 24 104 Left 0 WINDOW 3 24 16 Left 0 WINDOW 123 0 0 Left 0 WINDOW 39 24 -12 Left 0 SYMATTR InstName V2 SYMATTR Value 15 SYMATTR SpiceLine Rser=3D0.1 SYMBOL res -464 336 R0 SYMATTR InstName R28 SYMATTR Value 10k TEXT -480 1032 Left 0 !.ac oct 4 20 20000 TEXT -480 928 Left 0 ;* Tuning parts (nominal) R3 (5.6k), R9 (5.6k), R13 (3.9k), R17 (3.3k), R18 (2.0k), R20 (1.8K) TEXT 272 -360 Left 0 ;* TEXT 152 184 Left 0 ;* TEXT 320 264 Left 0 ;* TEXT 88 696 Left 0 ;* TEXT 584 384 Left 0 ;* TEXT 760 696 Left 0 ;*