Re: Low distortion sinewave oscillator without big capacitor.

"Edward Rawde" <invalid@invalid.invalid> wrote in message news:vsso97$1imi$1@nnrp.usenet.blueworldhosting.com...

"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:tcl2vjp49q4ga21itrpnmr4u3ts06vqffd@4ax.com...

On Fri, 4 Apr 2025 23:55:11 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:
>

"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:uop0vjp3d13t441ujfboi5aeeg08anm1je@4ax.com...

On Fri, 4 Apr 2025 16:29:27 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:
>

"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:add0vjdh2gcma0n9pfunq76n04cfbkhtnj@4ax.com...

On Fri, 4 Apr 2025 14:25:29 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:
>

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vsnufh$2ou7j$1@dont-email.me...

On 4/04/2025 11:33 am, JM wrote:

On Thu, 3 Apr 2025 19:25:33 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:
>

"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:qq8tujlpciqc2jrd0ibljmjr9pd37ip6hi@4ax.com...

On Sun, 30 Mar 2025 14:54:56 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:
>

Not long ago JM posted a 1KHz sinewave oscillator with very low distortion.
It used a 470uF non polarized capacitor which in practice would probably be made from two 1000uF capacitors.
There's nothing wrong with that but I wanted to see whether I could make a working circuit without needing such a large
capacitor.

....

Here's an almost fully practical circuit except for the current sources and sinks.

Version 4.1
SHEET 1 3020 2548
WIRE -1856 -336 -1952 -336
WIRE -1728 -336 -1792 -336
WIRE -1952 -224 -1952 -336
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WIRE -1728 -224 -1792 -224
WIRE -432 -224 -800 -224
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WIRE -2560 1152 -2560 976
WIRE -2208 1152 -2208 1088
WIRE -768 1264 -768 1184
FLAG -288 208 0
FLAG 112 208 0
FLAG -976 1040 vcc
FLAG -976 1104 vee
FLAG -656 128 vcc
FLAG -656 192 vee
FLAG -224 128 vcc
FLAG -224 192 vee
FLAG 176 128 vcc
FLAG 176 192 vee
FLAG -176 464 0
FLAG -96 528 vcc
FLAG -160 528 vee
FLAG -768 1264 vee
FLAG -656 1040 0
FLAG 512 208 output
FLAG -2064 720 vcc
FLAG -2064 656 vee
FLAG -2208 1232 vee
FLAG -2560 1232 vee
FLAG -2384 544 0
FLAG -2048 320 0
FLAG -2720 304 0
FLAG -2144 -128 vcc
FLAG -2624 -128 vcc
FLAG -1824 128 vcc
FLAG -1824 64 vee
FLAG -1888 48 0
FLAG -1824 -128 vcc
FLAG -1824 -64 vee
FLAG -1888 -48 0
FLAG -2704 720 vcc
FLAG -2704 656 vee
FLAG -1744 1088 vmod+
FLAG -1904 416 vgain
FLAG -880 1136 0
FLAG -3088 688 0
FLAG -3040 560 vcc
FLAG -3040 784 vee
FLAG -1776 592 0
FLAG -1888 832 vee
FLAG -1776 832 0
FLAG -1424 112 vcc
FLAG -1424 48 vee
FLAG -1456 -96 0
FLAG -1744 976 vmod-
SYMBOL res -592 16 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 10K
SYMBOL res -368 16 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 16K
SYMBOL res 48 16 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 16K
SYMBOL cap -192 16 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 10n
SYMBOL cap 208 16 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C2
SYMATTR Value 10n
SYMBOL res -336 -240 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R4
SYMATTR Value 10K
SYMBOL res -336 -80 M270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R5
SYMATTR Value 82k
SYMBOL cap -960 848 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C3
SYMATTR Value 1000n
SYMBOL res -784 1200 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R10
SYMATTR Value 820k
SYMBOL res -784 912 R0
SYMATTR InstName R11
SYMATTR Value 47k
SYMBOL res 48 592 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R18
SYMATTR Value 10K
SYMBOL res -96 432 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R19
SYMATTR Value 10k
SYMBOL diode -528 656 M0
SYMATTR InstName D2
SYMATTR Value 1N914
SYMBOL diode -288 656 M0
SYMATTR InstName D12
SYMATTR Value 1N914
SYMBOL diode -144 656 R0
SYMATTR InstName D13
SYMATTR Value 1N914
SYMBOL diode 304 656 M0
SYMATTR InstName D14
SYMATTR Value 1N914
SYMBOL res -560 736 R0
SYMATTR InstName R13
SYMATTR Value 68k
SYMBOL res -320 736 R0
SYMATTR InstName R14
SYMATTR Value 68k
SYMBOL res -112 736 M0
SYMATTR InstName R15
SYMATTR Value 68k
SYMBOL res 272 736 R0
SYMATTR InstName R16
SYMATTR Value 68k
SYMBOL OpAmps\LT1679 -656 160 R0
SYMATTR InstName U5
SYMBOL OpAmps\LT1679 -224 160 R0
SYMATTR InstName U6
SYMBOL OpAmps\LT1679 176 160 R0
SYMATTR InstName U8
SYMBOL res -624 272 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R8
SYMATTR Value 10k
SYMBOL res -832 272 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R9
SYMATTR Value 560
SYMBOL res -976 960 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R6
SYMATTR Value 47k
SYMBOL cap -1008 928 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C4
SYMATTR Value 10000n
SYMBOL OpAmps\LT1679 -128 528 R90
WINDOW 3 37 22 VRight 2
SYMATTR InstName U1
SYMBOL cap -1856 1072 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C6
SYMATTR Value 1000n
SYMBOL OpAmps\LT1679 -976 1072 M0
SYMATTR InstName U3
SYMBOL res -2144 848 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R23
SYMATTR Value 1k
SYMBOL npn -2144 640 M0
SYMATTR InstName Q4
SYMATTR Value 2N3904
SYMBOL res -2144 1072 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMATTR Value 540K
SYMBOL current -2208 1152 M0
SYMATTR InstName I1
SYMATTR Value 1m
SYMBOL res -2032 960 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMATTR Value 540K
SYMBOL current -2560 1152 R0
SYMATTR InstName I2
SYMATTR Value 1m
SYMBOL res -2368 416 M0
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SYMATTR Value 10
SYMBOL res -1968 432 M270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
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SYMATTR Value 3K
SYMBOL current -2144 -112 M0
SYMATTR InstName I3
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SYMBOL current -2624 -112 M0
SYMATTR InstName I4
SYMATTR Value 650u
SYMBOL res -1776 240 M270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R31
SYMATTR Value 1k
SYMBOL res -1776 -240 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R34
SYMATTR Value 1k
SYMBOL cap -1792 304 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C13
SYMATTR Value 33p
SYMBOL npn -2080 224 M0
SYMATTR InstName Q2B
SYMATTR Value BCM847BS
SYMBOL npn -2432 224 M0
SYMATTR InstName Q2A
SYMATTR Value BCM847BS
SYMBOL npn -2336 224 R0
WINDOW 3 -12 151 Left 2
SYMATTR Value BCM847BS
SYMATTR InstName Q1B
SYMBOL npn -2688 224 R0
WINDOW 3 -86 124 Left 2
SYMATTR Value BCM847BS
SYMATTR InstName Q1A
SYMBOL res -2624 848 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R35
SYMATTR Value 1k
SYMBOL npn -2624 640 R0
SYMATTR InstName Q3
SYMATTR Value 2N3904
SYMBOL cap -1792 -352 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C14
SYMATTR Value 33p
SYMBOL voltage -3040 544 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
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SYMBOL voltage -3040 688 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
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SYMATTR Value 15
SYMBOL cap -672 944 R0
SYMATTR InstName C8
SYMATTR Value 1000n
SYMBOL res -1904 704 R0
SYMATTR InstName R17
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SYMBOL res -1904 560 R0
SYMATTR InstName R20
SYMATTR Value 5k
SYMBOL cap -1792 720 R0
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SYMATTR Value 10n
SYMBOL OpAmps\LT1679 -1424 80 M180
SYMATTR InstName U4
SYMBOL res -1360 192 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R21
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SYMBOL res -1568 80 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R22
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SYMBOL res -1568 -16 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R25
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SYMBOL res -1504 -16 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
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SYMBOL cap -1152 64 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C11
SYMATTR Value 1000n
SYMBOL OpAmps\LT1679 -1824 -96 R0
WINDOW 3 -100 -54 Left 2
SYMATTR InstName U2
SYMBOL OpAmps\LT1679 -1824 96 M180
SYMATTR InstName U9
SYMBOL OpAmps\LT1679 -2704 688 M180
WINDOW 3 18 51 Left 2
SYMATTR InstName U10
SYMBOL OpAmps\LT1679 -2064 688 R180
WINDOW 3 16 46 Left 2
SYMATTR InstName U7
SYMBOL cap -1856 960 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C5
SYMATTR Value 1000n
TEXT -3288 368 Left 2 !.tran 0 10 0 1u startup
TEXT -3288 312 Left 2 !.options plotwinsize=0 numdgt=15
TEXT -552 1176 Left 2 !.MODEL BCM847BS NPN IS = 1.822E-14 NF = 0.9932 ISE= 2.894E-16 NE = 1.4 \n+ BF = 324.4 IKF = 0.109 VAF = 82 NR
= 0.9931 ISC = 9.982E-12 NC = 1.763 \n+ BR = 8.29 IKR = 0.09 VAR = 17.9 RB = 10 IRB = 5E-06 RBM = 5 RE = 0.649 \n+ RC = 0.7014 CJE =
1.244E-11 VJE = 0.7579 MJE = 0.3656 TF = 4.908E-10 \n+ XTF = 9.51 VTF = 2.927 ITF = 0.3131 PTF = 0 CJC = 3.347E-12 VJC = 0.5463 \n+
MJC = 0.391 XCJC = 0.6193 TR = 9E-08 CJS = 0 VJS = 0.75 MJS = 0.333 \n+ XTB = 0 XTI = 3 EG = 1.11 FC = 0.979