Re: Five transistor version of the low distortion sine-wave oscillator

"Edward Rawde" <invalid@invalid.invalid> wrote in message news:vtlm0g$21p4$1@nnrp.usenet.blueworldhosting.com...

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vtl0bc$364bt$1@dont-email.me...

On 15/04/2025 1:56 am, Edward Rawde wrote:

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

On 12/04/2025 6:27 pm, Bill Sloman wrote:

Edward Rawde posted an eight-transistor low distortion sine wave oscillator circuit recently, and John May pointed out that
you
could leave out half the transistors.
>
I couldn't immediately see exactly how either of the circuits worked, though I could get the simulations to run under LTSpice
and
see roughly what was going on.
>
I've now dug a bit deeper. Here is a five transistor version of John May's four transistor version.

>

As a first prototype I'd build the circuit below using only through hole components except where through hole is either not
available or not desirable such as ceramic capacitors.
Resistors may be done with pads so that through hole resistors can be soldered on in such a way that they're rather easier to remove
than an 0402.

In recent years I've been asked if I can repair equipment such as a music keyboard.
If the internals are surface mount and the problem isn't an obvious one (eg wrong power adapter) I will generally decline to try.
Find someone who can get the dried up surface mount electrolytics off without damaging the board, if it hasn't been damaged already
by leaking electrolyte.
There may well be equipment which can do it but I don't have it.

The second prototype for this circuit would be all surface mount.

Unless I win a lottery I won't be either building it or figuring out what I need to test it.

I'm done with sinewave oscillators except for being curious about how to design a suitable sample and hold circuit in the other
circuit JM posted.
Use of a comparator to obtain the sampling signal might reintroduce all the harmonics we want to get rid of.

Version 4.1
SHEET 1 3020 2548
WIRE 80 -208 -288 -208
WIRE 800 -208 160 -208
WIRE -288 -96 -288 -208
WIRE 80 -96 -288 -96
WIRE 400 -96 160 -96
WIRE -288 32 -288 -96
WIRE -176 32 -288 32
WIRE -32 32 -96 32
WIRE 48 32 -32 32
WIRE 208 32 128 32
WIRE 256 32 208 32
WIRE 400 32 400 -96
WIRE 400 32 320 32
WIRE 464 32 400 32
WIRE 608 32 544 32
WIRE 656 32 608 32
WIRE 800 32 800 -208
WIRE 800 32 720 32
WIRE 848 32 800 32
WIRE 992 32 928 32
WIRE 1040 32 992 32
WIRE 1184 32 1120 32
WIRE -752 48 -816 48
WIRE -624 48 -688 48
WIRE -288 144 -288 32
WIRE -176 144 -288 144
WIRE 208 144 208 32
WIRE 256 144 208 144
WIRE 608 144 608 32
WIRE 656 144 608 144
WIRE 992 144 992 32
WIRE 1040 144 992 144
WIRE -816 160 -816 48
WIRE -752 160 -816 160
WIRE -624 160 -624 48
WIRE -624 160 -672 160
WIRE -32 160 -32 32
WIRE -32 160 -112 160
WIRE 400 160 400 32
WIRE 400 160 320 160
WIRE 800 160 800 32
WIRE 800 160 720 160
WIRE 1184 160 1184 32
WIRE 1184 160 1104 160
WIRE 1216 160 1184 160
WIRE -176 176 -288 176
WIRE 256 176 224 176
WIRE 656 176 624 176
WIRE 1040 176 1008 176
WIRE 224 208 224 176
WIRE 624 208 624 176
WIRE 1008 208 1008 176
WIRE -1968 224 -1968 144
WIRE -1008 272 -1104 272
WIRE -816 272 -816 160
WIRE -816 272 -944 272
WIRE -736 272 -816 272
WIRE -624 288 -624 160
WIRE -624 288 -672 288
WIRE -544 288 -624 288
WIRE -416 288 -480 288
WIRE -288 288 -288 176
WIRE -288 288 -336 288
WIRE -208 288 -288 288
WIRE 208 288 -128 288
WIRE 400 288 400 160
WIRE 400 288 208 288
WIRE -736 304 -816 304
WIRE -816 336 -816 304
WIRE 400 336 400 288
WIRE -1968 400 -1968 304
WIRE -1856 400 -1968 400
WIRE -1664 400 -1776 400
WIRE 208 400 208 288
WIRE 208 400 -1600 400
WIRE 400 448 400 416
WIRE 544 448 400 448
WIRE 368 464 336 464
WIRE -1968 496 -1968 400
WIRE -1968 496 -2304 496
WIRE 368 496 368 464
WIRE 400 496 400 448
WIRE 544 496 544 448
WIRE -2432 544 -2432 496
WIRE -2304 560 -2304 496
WIRE -2240 560 -2304 560
WIRE -2144 560 -2176 560
WIRE -1360 576 -1360 480
WIRE 384 608 384 560
WIRE 544 608 544 576
WIRE 544 608 384 608
WIRE -1968 640 -1968 496
WIRE -32 656 -32 160
WIRE 208 656 208 400
WIRE 384 656 384 608
WIRE 800 656 800 160
WIRE -2304 672 -2304 560
WIRE -2256 672 -2304 672
WIRE -2144 688 -2144 560
WIRE -2144 688 -2192 688
WIRE -2032 688 -2144 688
WIRE -1360 688 -1360 656
WIRE -1104 688 -1104 272
WIRE -1104 688 -1360 688
WIRE -2432 704 -2432 624
WIRE -2256 704 -2432 704
WIRE -32 784 -32 720
WIRE 208 784 208 720
WIRE 384 784 384 720
WIRE 800 784 800 720
WIRE -2432 832 -2432 704
WIRE -2432 832 -2544 832
WIRE -2544 864 -2544 832
WIRE -2432 864 -2432 832
WIRE -1360 880 -1360 688
WIRE -1968 928 -1968 736
WIRE -1424 928 -1968 928
WIRE -32 944 -32 864
WIRE 208 944 208 864
WIRE 384 944 384 864
WIRE 800 944 800 864
WIRE -2544 960 -2544 928
WIRE -2432 1008 -2432 944
WIRE -32 1120 -32 1024
WIRE 96 1120 -32 1120
WIRE 208 1120 208 1024
WIRE 208 1120 96 1120
WIRE 384 1120 384 1024
WIRE 384 1120 208 1120
WIRE 800 1120 800 1024
WIRE 800 1120 384 1120
WIRE -2160 1152 -2160 1040
WIRE -1664 1152 -1664 1040
WIRE -1968 1200 -1968 928
WIRE -1968 1200 -2096 1200
WIRE -1904 1200 -1968 1200
WIRE -1728 1200 -1904 1200
WIRE 96 1200 96 1120
WIRE -2480 1216 -2480 1184
WIRE -2480 1216 -2528 1216
WIRE -2528 1232 -2528 1216
WIRE -1360 1232 -1360 976
WIRE -2480 1248 -2480 1216
WIRE -1664 1280 -1664 1248
WIRE -1424 1280 -1664 1280
WIRE -2160 1296 -2160 1248
WIRE -2160 1296 -2240 1296
WIRE 96 1312 96 1264
WIRE -2240 1344 -2240 1296
WIRE -1664 1360 -1664 1280
WIRE -32 1424 -32 1120
WIRE -1360 1440 -1360 1328
WIRE -320 1440 -416 1440
WIRE -160 1440 -256 1440
WIRE -2240 1488 -2240 1424
WIRE -1664 1504 -1664 1440
WIRE -416 1520 -416 1440
WIRE -368 1520 -416 1520
WIRE -256 1520 -304 1520
WIRE -160 1520 -160 1440
WIRE -160 1520 -176 1520
WIRE -160 1632 -160 1520
WIRE -160 1632 -240 1632
WIRE -32 1632 -32 1504
WIRE -32 1632 -160 1632
WIRE 48 1632 -32 1632
WIRE 176 1632 128 1632
WIRE 272 1632 240 1632
WIRE 368 1632 336 1632
WIRE 480 1632 432 1632
WIRE 576 1632 544 1632
WIRE 688 1632 640 1632
WIRE 816 1632 816 1616
WIRE 816 1632 752 1632
WIRE -2160 1648 -2160 1296
WIRE -1648 1648 -2160 1648
WIRE -416 1648 -416 1520
WIRE -416 1648 -1568 1648
WIRE -304 1648 -416 1648
WIRE -208 1664 -240 1664
WIRE -1904 1712 -1904 1200
WIRE -2160 1760 -2160 1648
WIRE -1968 1760 -2160 1760
WIRE -208 1776 -208 1664
WIRE -1904 1888 -1904 1808
FLAG 224 208 0
FLAG 624 208 0
FLAG -272 1616 vcc
FLAG -272 1680 vee
FLAG -2528 1232 0
FLAG -2480 1104 vcc
FLAG -2480 1328 vee
FLAG -144 128 vcc
FLAG -144 192 vee
FLAG 288 128 vcc
FLAG 288 192 vee
FLAG 688 128 vcc
FLAG 688 192 vee
FLAG 336 464 0
FLAG 416 528 vcc
FLAG 352 528 vee
FLAG -2224 656 vcc
FLAG -1968 144 vcc
FLAG -2224 720 vee
FLAG -1360 480 vcc
FLAG -2432 496 vcc
FLAG -2432 1008 0
FLAG -1360 1440 0
FLAG -704 256 vcc
FLAG -704 320 vee
FLAG -816 336 0
FLAG -1664 1504 vee
FLAG -1904 1888 0
FLAG -1664 1040 vcc
FLAG -2160 1040 vcc
FLAG -208 1776 0
FLAG -2544 960 0
FLAG 816 1616 vee
FLAG -2240 1488 vee
FLAG 96 1312 0
FLAG 1008 208 0
FLAG 1216 160 vout
FLAG 1072 128 vcc
FLAG 1072 192 vee
SYMBOL res -80 16 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 10K
SYMBOL res 144 16 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 16K
SYMBOL res 560 16 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 16K
SYMBOL cap 320 16 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 10n
SYMBOL cap 720 16 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C2
SYMATTR Value 10n
SYMBOL res 176 -224 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R4
SYMATTR Value 10K
SYMBOL res 176 -80 M270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R5
SYMATTR Value 82k
SYMBOL cap -256 1424 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C3
SYMATTR Value 1000n
SYMBOL res 32 1648 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R10
SYMATTR Value 680K
SYMBOL diode 176 1648 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D1
SYMATTR Value 1N914
SYMBOL res -48 1408 R0
SYMATTR InstName R11
SYMATTR Value 40.2K
SYMBOL res 560 592 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R18
SYMATTR Value 10K
SYMBOL res 416 432 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R19
SYMATTR Value 10k
SYMBOL diode -16 656 M0
SYMATTR InstName D2
SYMATTR Value 1N914
SYMBOL diode 224 656 M0
SYMATTR InstName D12
SYMATTR Value 1N914
SYMBOL diode 368 656 R0
SYMATTR InstName D13
SYMATTR Value 1N914
SYMBOL diode 816 656 M0
SYMATTR InstName D14
SYMATTR Value 1N914
SYMBOL res -48 768 R0
SYMATTR InstName R13
SYMATTR Value 56k
SYMBOL res 192 768 R0
SYMATTR InstName R14
SYMATTR Value 56k
SYMBOL res 400 768 M0
SYMATTR InstName R15
SYMATTR Value 56k
SYMBOL res 784 768 R0
SYMATTR InstName R16
SYMATTR Value 56k
SYMBOL voltage -2480 1088 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value 15
SYMBOL voltage -2480 1232 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V4
SYMATTR Value 15
SYMBOL OpAmps\LT1679 -144 160 R0
SYMATTR InstName U5
SYMBOL OpAmps\LT1679 288 160 R0
SYMATTR InstName U6
SYMBOL OpAmps\LT1679 688 160 R0
SYMATTR InstName U8
SYMBOL res -112 272 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R8
SYMATTR Value 10k
SYMBOL res -320 272 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R9
SYMATTR Value 560
SYMBOL cap -480 272 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C8
SYMATTR Value 1000n
SYMBOL res -272 1536 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R6
SYMATTR Value 100k
SYMBOL cap -304 1504 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C4
SYMATTR Value 10000n
SYMBOL OpAmps\LT1679 384 528 R90
WINDOW 3 37 22 VRight 2
SYMATTR InstName U1
SYMBOL pnp -2032 736 M180
WINDOW 3 84 0 Left 2
SYMATTR Value 2N3906
SYMATTR InstName Q4
SYMBOL res -1984 208 R0
SYMATTR InstName R12
SYMATTR Value 82k
SYMBOL res -1760 384 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R25
SYMATTR Value 2.7Meg
SYMBOL cap -2176 544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C7
SYMATTR Value 10p
SYMBOL npn -2096 1152 M0
SYMATTR InstName Q1A
SYMATTR Value NSS40301MDR2G
SYMBOL npn -1728 1152 R0
SYMATTR InstName Q1B
SYMATTR Value NSS40301MDR2G
SYMBOL npn -1424 1232 R0
SYMATTR InstName Q2B
SYMATTR Value NSS40301MDR2G
SYMBOL npn -1968 1712 R0
SYMATTR InstName Q2A
SYMATTR Value NSS40301MDR2G
SYMBOL res -1552 1632 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R28
SYMATTR Value 68k
SYMBOL res -1376 560 R0
SYMATTR InstName R29
SYMATTR Value 100k
SYMBOL res -2448 528 R0
SYMATTR InstName R32
SYMATTR Value 10k
SYMBOL res -2448 848 R0
SYMATTR InstName R33
SYMATTR Value 15k
SYMBOL cap -944 256 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C12
SYMATTR Value 1000n
SYMBOL res -656 144 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R7
SYMATTR Value 14k
SYMBOL cap -688 32 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C5
SYMATTR Value 10p
SYMBOL cap -1600 384 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C6
SYMATTR Value 100n
SYMBOL res -1648 1456 R180
WINDOW 0 31 76 Left 2
WINDOW 3 31 40 Left 2
SYMATTR InstName R17
SYMATTR Value 22k
SYMBOL OpAmps\LT1679 -704 288 R0
SYMATTR InstName U2
SYMBOL OpAmps\LT1679 -272 1648 M0
SYMATTR InstName U3
SYMBOL OpAmps\LT1679 -2224 688 R0
SYMATTR InstName U4
SYMBOL cap -2560 864 R0
SYMATTR InstName C9
SYMATTR Value 10n
SYMBOL res -2224 1440 R180
WINDOW 0 31 76 Left 2
WINDOW 3 31 40 Left 2
SYMATTR InstName R20
SYMATTR Value 27k
SYMBOL npn -1424 880 R0
SYMATTR InstName Q3
SYMATTR Value 2N3904
SYMBOL diode 272 1648 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D3
SYMATTR Value 1N914
SYMBOL diode 368 1648 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D4
SYMATTR Value 1N914
SYMBOL diode 480 1648 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D5
SYMATTR Value 1N914
SYMBOL diode 576 1648 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D6
SYMATTR Value 1N914
SYMBOL diode 688 1648 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D7
SYMATTR Value 1N914
SYMBOL res -48 928 R0
SYMATTR InstName R21
SYMATTR Value 22k
SYMBOL res 192 928 R0
SYMATTR InstName R22
SYMATTR Value 20k
SYMBOL res 368 928 R0
SYMATTR InstName R23
SYMATTR Value 20k
SYMBOL res 784 928 R0
SYMATTR InstName R24
SYMATTR Value 18k
SYMBOL cap 80 1200 R0
SYMATTR InstName C10
SYMATTR Value 1000n
SYMBOL res 944 16 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R26
SYMATTR Value 10k
SYMBOL OpAmps\LT1679 1072 160 R0
SYMATTR InstName U7
SYMBOL res 1136 16 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R27
SYMATTR Value 10k
TEXT -2792 1560 Left 2 !.tran 0 10 0 1u startup
TEXT -2792 1504 Left 2 !.options plotwinsize=0 numdgt=15
TEXT -2248 -112 Left 2 ;Low distortion 1KHz oscillator. Edward Rawde 30 March 2025.\nBased on designs by JM and BS. Re-worked by JM,
getting rid of half the transistors,\nand again by Bill Sloman, making Q1A/B and Q2A/B close matched transistor pairs\nand adding
the cascode transistor at Q3, 12th April 2025..
TEXT -2896 16 Left 2 !.MODEL NSS40301MDR2G NPN\n+is=6.87023e-12 bf=445.496 nf=1.08926 vaf=60.529\n+ikf=7.23313 ise=2.38192e-09 ne=4
br=23.6872\n+nr=1.10701 var=8.89608 ikr=1.25064 isc=1e-16 \n+nc=1.13174 rb=905.334,irb=2.30349e-07 rbm=1e-10\n+re=0.00600548
rc=0.0300274 xtb=1.2219 xti=4,\n+eg=1.05 cje=3.80477e-10 vje=0.912237
mje=0.397194,\n+tf=5.90916e-10,xtf=0.0998483,vtf=7.09172,itf=0.010481,\n+cjc=8.35472e-11 vjc=0.702862 mjc=0.43477
xcjc=0.899998\n+fc=0.414631 cjs=0 vjs=0.75 mjs=0.5 \n+tr=5.64658e-08 ptf=0,kf=0 af=1