Re: High purity 1kHz oscillator

"Edward Rawde" <invalid@invalid.invalid> wrote in message news:vf7c4h$1m5m$1@nnrp.usenet.blueworldhosting.com...

But I suspect that component tolerances and mismatched FETs will ruin it.

Can anyone tell me what causes the following feature of the circuit below?
This circuit is not exactly the same as the previous one but all versions seem to have this behaviour.

Run a simulation and view the output.

You can see that there's distortion until about 1.8 seconds when it disappears.
View J1 or J2 gate voltage.
You can see that the crud suddenly reduces at 1.8 seconds.
What's causing that and is there a way to make the circuit always run in reduced crud mode?

I'll be back in about a week to thank whoever can explain this.

Version 4
SHEET 1 2196 916
WIRE 48 -576 16 -576
WIRE 544 -576 112 -576
WIRE 736 -512 688 -512
WIRE 864 -512 816 -512
WIRE -160 -496 -256 -496
WIRE -16 -496 -160 -496
WIRE 16 -496 16 -576
WIRE 16 -496 -16 -496
WIRE 48 -496 16 -496
WIRE 512 -496 112 -496
WIRE -160 -480 -160 -496
WIRE -256 -464 -256 -496
WIRE -16 -416 -16 -496
WIRE 800 -400 800 -416
WIRE 864 -384 864 -512
WIRE 864 -384 832 -384
WIRE 896 -384 864 -384
WIRE 1008 -384 976 -384
WIRE -256 -368 -256 -400
WIRE -160 -368 -160 -400
WIRE -160 -368 -256 -368
WIRE -48 -368 -160 -368
WIRE 144 -368 48 -368
WIRE 544 -368 544 -576
WIRE 560 -368 544 -368
WIRE 688 -368 688 -512
WIRE 688 -368 640 -368
WIRE 768 -368 688 -368
WIRE 864 -352 832 -352
WIRE 48 -336 16 -336
WIRE 544 -336 544 -368
WIRE 544 -336 112 -336
WIRE -256 -320 -256 -368
WIRE -256 -320 -304 -320
WIRE 800 -320 800 -336
WIRE -160 -256 -256 -256
WIRE -16 -256 -160 -256
WIRE 16 -256 16 -336
WIRE 16 -256 -16 -256
WIRE 48 -256 16 -256
WIRE 512 -256 512 -496
WIRE 512 -256 112 -256
WIRE 864 -256 864 -352
WIRE -160 -240 -160 -256
WIRE -256 -224 -256 -256
WIRE 512 -224 512 -256
WIRE -16 -176 -16 -256
WIRE -304 -128 -304 -320
WIRE -256 -128 -256 -160
WIRE -256 -128 -304 -128
WIRE -160 -128 -160 -160
WIRE -160 -128 -256 -128
WIRE -80 -128 -160 -128
WIRE -48 -128 -80 -128
WIRE 80 -128 48 -128
WIRE 144 -128 144 -368
WIRE 144 -128 80 -128
WIRE 160 -128 144 -128
WIRE 272 -128 240 -128
WIRE 320 -128 272 -128
WIRE 448 -128 400 -128
WIRE 512 -96 512 -144
WIRE 1008 -96 1008 -384
WIRE 1008 -96 512 -96
WIRE -304 -80 -304 -128
WIRE -80 -64 -80 -128
WIRE -32 -64 -80 -64
WIRE 80 -64 80 -128
WIRE 80 -64 48 -64
WIRE 832 -64 720 -64
WIRE 1056 -64 832 -64
WIRE 272 -16 272 -128
WIRE 320 -16 272 -16
WIRE 448 -16 448 -128
WIRE 448 -16 400 -16
WIRE 832 -16 832 -64
WIRE 272 16 272 -16
WIRE 272 16 48 16
WIRE 720 16 720 -64
WIRE -304 32 -304 0
WIRE 128 96 128 80
WIRE -272 112 -352 112
WIRE -208 112 -272 112
WIRE 48 112 48 16
WIRE 96 112 48 112
WIRE 912 112 912 96
WIRE 432 128 160 128
WIRE 448 128 448 -16
WIRE 448 128 432 128
WIRE 512 128 512 -96
WIRE 512 128 448 128
WIRE 576 128 512 128
WIRE 704 128 656 128
WIRE 720 128 720 80
WIRE 720 128 704 128
WIRE 752 128 720 128
WIRE 832 128 832 64
WIRE 832 128 816 128
WIRE 880 128 832 128
WIRE 96 144 -80 144
WIRE 1056 144 1056 -64
WIRE 1056 144 944 144
WIRE 1168 144 1056 144
WIRE 1264 144 1168 144
WIRE -352 160 -352 112
WIRE 880 160 848 160
WIRE -208 176 -208 112
WIRE 128 176 128 160
WIRE 912 192 912 176
WIRE 704 208 704 128
WIRE -80 224 -80 144
WIRE 16 224 -80 224
WIRE 224 224 16 224
WIRE 304 224 288 224
WIRE 432 224 432 128
WIRE 432 224 384 224
WIRE -80 240 -80 224
WIRE 16 240 16 224
WIRE 848 256 848 160
WIRE -352 336 -352 240
WIRE -352 336 -432 336
WIRE -80 336 -80 320
WIRE -32 336 -80 336
WIRE 16 336 16 304
WIRE 16 336 -32 336
WIRE -432 352 -432 336
WIRE -352 352 -352 336
WIRE -208 352 -208 240
WIRE -208 352 -352 352
WIRE 704 352 704 288
WIRE -32 368 -32 336
WIRE -352 432 -352 352
WIRE -208 448 -208 352
WIRE -352 608 -352 512
WIRE -272 608 -352 608
WIRE -208 608 -208 512
WIRE -208 608 -272 608
FLAG -432 352 0
FLAG 1168 144 output
FLAG -304 32 0
FLAG 848 256 0
FLAG 704 352 0
FLAG 912 96 V+
FLAG 912 192 V-
FLAG 128 80 V+
FLAG 128 176 V-
FLAG -272 112 V+
FLAG -272 608 V-
FLAG -32 368 0
FLAG 800 -416 V+
FLAG 800 -320 V-
FLAG 864 -256 0
SYMBOL voltage -352 144 R0
WINDOW 123 0 0 Left 0
WINDOW 39 10 135 Left 2
WINDOW 0 12 7 Left 2
WINDOW 3 15 104 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V1
SYMATTR Value 12
SYMBOL res 400 208 R90
WINDOW 0 -7 54 VBottom 2
WINDOW 3 37 50 VTop 2
SYMATTR InstName R1
SYMATTR Value 10.5k
SYMBOL cap 288 208 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 15n
SYMBOL cap 32 304 R180
WINDOW 0 -33 54 Left 2
WINDOW 3 -49 18 Left 2
SYMATTR InstName C2
SYMATTR Value 15n
SYMBOL polcap -224 176 R0
SYMATTR InstName C4
SYMATTR Value 100�
SYMBOL OpAmps\LT1057 128 64 R0
SYMATTR InstName U2
SYMBOL res -176 -256 R0
SYMATTR InstName R6
SYMATTR Value 47k
SYMBOL res 256 -144 R90
WINDOW 0 -1 46 VBottom 2
WINDOW 3 35 56 VTop 2
SYMATTR InstName R7
SYMATTR Value 6.34k
SYMBOL res 416 -144 R90
WINDOW 0 -4 61 VBottom 2
WINDOW 3 39 55 VTop 2
SYMATTR InstName R8
SYMATTR Value 13k
SYMBOL schottky 48 -240 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D1
SYMATTR Value BAT54
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL njf 48 -176 R90
WINDOW 0 -37 23 VRight 2
WINDOW 3 -9 -3 VRight 2
SYMATTR InstName J1
SYMATTR Value J112
SYMBOL voltage -352 416 R0
WINDOW 123 0 0 Left 0
WINDOW 39 10 135 Left 2
WINDOW 0 10 0 Left 2
WINDOW 3 15 104 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V2
SYMATTR Value 12
SYMBOL polcap -224 448 R0
SYMATTR InstName C5
SYMATTR Value 100�
SYMBOL res -96 224 R0
SYMATTR InstName R2
SYMATTR Value 10.5k
SYMBOL cap -240 -160 R180
WINDOW 0 -27 59 Left 2
WINDOW 3 -33 2 Left 2
SYMATTR InstName C3
SYMATTR Value 10�
SYMATTR Description Polarized Capacitor
SYMATTR Type polcap
SYMATTR SpiceLine V=4 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60G106ME15" type="X5R"
SYMBOL res 64 -80 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 330
SYMBOL res 416 -32 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R5
SYMATTR Value 820k
SYMBOL schottky 112 -512 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D2
SYMATTR Value BAT54
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -176 -496 R0
SYMATTR InstName R4
SYMATTR Value 47k
SYMBOL cap -240 -400 R180
WINDOW 0 -27 61 Left 2
WINDOW 3 -37 8 Left 2
SYMATTR InstName C6
SYMATTR Value 10�
SYMATTR Description Polarized Capacitor
SYMATTR Type polcap
SYMATTR SpiceLine V=4 Irms=0 Rser=0 Lser=0 mfg="Murata" pn="GRM155R60G106ME15" type="X5R"
SYMBOL res 496 -240 R0
SYMATTR InstName R9
SYMATTR Value 100
SYMBOL res -320 -96 R0
SYMATTR InstName R10
SYMATTR Value 1.5
SYMBOL pjf 48 -416 R90
WINDOW 0 -34 29 VRight 2
WINDOW 3 -9 -1 VRight 2
SYMATTR InstName J2
SYMATTR Value J175
SYMBOL OpAmps\LT1057 912 80 R0
SYMATTR InstName U1
SYMBOL res 672 112 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R11
SYMATTR Value 5.1k
SYMBOL cap 752 112 M90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C7
SYMATTR Value 68n
SYMBOL res 688 192 R0
SYMATTR InstName R12
SYMATTR Value 13k
SYMBOL res 816 -32 R0
SYMATTR InstName R13
SYMATTR Value 6.2k
SYMBOL cap 704 16 R0
SYMATTR InstName C8
SYMATTR Value 10n
SYMBOL OpAmps\LT1057 800 -432 M0
SYMATTR InstName U3
SYMBOL res 832 -528 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R14
SYMATTR Value 10k
SYMBOL res 992 -400 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R15
SYMATTR Value 10k
SYMBOL res 656 -384 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R16
SYMATTR Value 100
SYMBOL schottky 112 -592 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D3
SYMATTR Value BAT54
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 48 -320 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D4
SYMATTR Value BAT54
SYMATTR Description Diode
SYMATTR Type diode
TEXT -80 472 Left 2 !.tran 0 10s 2s startup
TEXT -248 -640 Left 2 ;Edward Rawde's high purity sinewave oscillator. 22 Oct 2024