Re: Random thoughts on sinewave oscillators

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vesrnm$35jgr$1@dont-email.me...

On 17/10/2024 7:55 am, Edward Rawde wrote:

Is the reason why this doesn't produce a better looking sinewave because the amplifier slew rate is faster going down than it is
going up or some other reason?
>
Ignore the wild decoupling, it took me long enough to get the concept to work at all.
>
I'm aware that a single package containing two op amps could probably do a much better job.

>
https://www.analog.com/media/en/technical-documentation/application-notes/AN132f.pdf
>
has a pretty good example of a sine wave oscillator. I've speculated that a four quadrant analogue multiplier could offer a better
gain control mechanism.
>
https://www.analog.com/media/en/technical-documentation/data-sheets/AD734.pdf
>
though it is hideously expensive. The simulation I worked up used two with the second one controlling a quadrature input to give
you smooth control of the frequency of oscillation in addition to its amplitude.
>
I thought about building one, but there's no obvious application.
>
--
Bill Sloman, Sydney
>

Thanks Bill.

It may be that there's something wrong with the concept I'm trying to use because the circuit below can't find a control point which
produces sine waves.
It just produces all or nothing at a repetition rate of about 80 Hz.
I saw similar issues while simulating the discrete circuit.

Version 4
SHEET 1 2164 680
WIRE -384 -48 -560 -48
WIRE -240 -48 -384 -48
WIRE -80 -48 -240 -48
WIRE 144 -48 -80 -48
WIRE 864 -48 144 -48
WIRE 992 -48 864 -48
WIRE 1104 -48 992 -48
WIRE 864 -16 864 -48
WIRE 992 -16 992 -48
WIRE -240 32 -240 -48
WIRE -80 32 -80 -48
WIRE 64 64 -16 64
WIRE 192 64 64 64
WIRE 304 64 272 64
WIRE -560 80 -560 -48
WIRE -16 80 -16 64
WIRE 304 96 304 64
WIRE 336 96 304 96
WIRE 448 96 416 96
WIRE 544 96 512 96
WIRE 592 96 544 96
WIRE 688 96 656 96
WIRE 736 96 688 96
WIRE 864 96 864 64
WIRE 864 96 816 96
WIRE -384 112 -384 -48
WIRE 144 112 144 -48
WIRE 1104 112 1104 -48
WIRE 64 128 64 64
WIRE 112 128 64 128
WIRE 864 128 864 96
WIRE 1072 128 864 128
WIRE 304 144 304 96
WIRE 304 144 176 144
WIRE 1216 144 1136 144
WIRE -240 160 -240 112
WIRE -176 160 -240 160
WIRE 112 160 -176 160
WIRE 544 160 544 96
WIRE 688 160 688 96
WIRE 992 160 992 64
WIRE 1072 160 992 160
WIRE 864 176 864 128
WIRE -240 192 -240 160
WIRE -80 208 -80 112
WIRE -16 208 -16 144
WIRE -16 208 -80 208
WIRE -80 224 -80 208
WIRE -16 224 -16 208
WIRE 992 224 992 160
WIRE 96 288 32 288
WIRE -560 336 -560 160
WIRE -384 336 -384 176
WIRE -384 336 -560 336
WIRE -240 336 -240 272
WIRE -240 336 -384 336
WIRE -80 336 -80 304
WIRE -80 336 -240 336
WIRE -48 336 -80 336
WIRE -16 336 -16 320
WIRE -16 336 -48 336
WIRE 144 336 144 176
WIRE 144 336 -16 336
WIRE 544 336 544 224
WIRE 544 336 144 336
WIRE 688 336 688 224
WIRE 688 336 544 336
WIRE 864 336 864 240
WIRE 864 336 688 336
WIRE 992 336 992 304
WIRE 992 336 864 336
WIRE 1104 336 1104 176
WIRE 1104 336 992 336
WIRE -48 352 -48 336
WIRE -560 384 -560 336
WIRE 96 384 96 288
WIRE 1216 384 1216 144
WIRE 1216 384 96 384
WIRE -176 448 -176 160
WIRE -48 448 -48 416
WIRE -48 448 -176 448
WIRE 16 448 -48 448
WIRE 96 448 80 448
WIRE 304 448 304 144
WIRE 304 448 176 448
WIRE 432 448 304 448
WIRE 480 448 432 448
FLAG -560 384 0
FLAG 432 448 output
SYMBOL OpAmps\OP07 144 80 R0
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SYMBOL voltage -560 64 R0
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WINDOW 39 24 124 Left 2
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SYMATTR Value 12
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WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMATTR Value 12k
SYMBOL cap 80 432 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 15n
SYMBOL cap -32 416 R180
WINDOW 0 -33 54 Left 2
WINDOW 3 -49 18 Left 2
SYMATTR InstName C2
SYMATTR Value 15n
SYMBOL res 288 48 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 1700
SYMBOL res -224 128 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R4
SYMATTR Value 24k
SYMBOL polcap -32 80 R0
SYMATTR InstName C3
SYMATTR Value 10�
SYMBOL res -224 288 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R5
SYMATTR Value 24k
SYMBOL polcap -400 112 R0
SYMATTR InstName C4
SYMATTR Value 100�
SYMBOL pjf 32 224 M0
WINDOW 0 -28 43 Left 2
WINDOW 3 -53 90 Left 2
SYMATTR InstName J1
SYMATTR Value J175
SYMBOL res -96 208 R0
WINDOW 0 -39 37 Left 2
WINDOW 3 -48 70 Left 2
SYMATTR InstName R6
SYMATTR Value 1k
SYMBOL res -96 16 R0
WINDOW 0 -48 37 Left 2
WINDOW 3 -69 66 Left 2
SYMATTR InstName R8
SYMATTR Value 220k
SYMBOL res 432 80 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R9
SYMATTR Value 1k
SYMBOL cap 512 80 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C5
SYMATTR Value 0.1�
SYMBOL diode 528 160 R0
WINDOW 0 39 34 Left 2
WINDOW 3 31 68 Left 2
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL diode 656 80 R90
WINDOW 0 64 31 VBottom 2
WINDOW 3 -30 29 VTop 2
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL cap 672 160 R0
SYMATTR InstName C6
SYMATTR Value 0.1�
SYMBOL res 832 80 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R11
SYMATTR Value 22k
SYMBOL cap 848 176 R0
SYMATTR InstName C7
SYMATTR Value 1�
SYMBOL res 848 -32 R0
WINDOW 0 41 43 Left 2
WINDOW 3 37 73 Left 2
SYMATTR InstName R12
SYMATTR Value 100k
SYMBOL OpAmps\OP07 1104 80 R0
SYMATTR InstName U2
SYMBOL res 1008 80 R180
WINDOW 0 -53 70 Left 2
WINDOW 3 -49 43 Left 2
SYMATTR InstName R10
SYMATTR Value 10k
SYMBOL res 1008 320 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R13
SYMATTR Value 2k
TEXT -544 360 Left 2 !.tran 10