Re: Random thoughts on sinewave oscillators

On 18/10/2024 4:46 pm, john larkin wrote:

On Fri, 18 Oct 2024 11:25:19 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:
 

"piglet" <erichpwagner@hotmail.com> wrote in message news:vetde5$38sbk$1@dont-email.me...

Edward Rawde <invalid@invalid.invalid> wrote:

>
The circuit below produces a reasonable looking sinewave but the rise
time still seems to be slower than the fall time. It may be that the
amplifier in use is not ideal for this.
>

>
Could that just be second harmonic distortion? You could test the amplifier
by uncoupling the Wien network and injecting test inputs.
>
Elsewhere I think your amplitude control problems could be simply due to
too much gain.

>
Perhaps, but I've not so far been able to get the circuit I posted in response to Bill to produce a sine wave no matter what I do
with the control loop gain.
It either grows to clipping or dies.
>

>
>
-- piglet

>

 I do a lot of instant-start LC oscillators as the timebase of
triggered delay generators. I let them clip just a bit to stabilize
amplitude.
 

Here is an amusing oscillator that has a voltage follower as the active stage - it has no voltage gain so some people say it cannot work - they are wrong of course.
Amplitude grows to power rail limits and non-linearities creep in.
Version 4
SHEET 1 1132 680
WIRE 640 -272 400 -272
WIRE 784 -272 640 -272
WIRE 928 -272 784 -272
WIRE 1072 -272 928 -272
WIRE 640 -224 640 -272
WIRE 400 -144 400 -272
WIRE 784 -144 784 -272
WIRE 640 -96 640 -144
WIRE 720 -96 640 -96
WIRE 640 -64 640 -96
WIRE 928 -48 928 -272
WIRE 1072 -48 1072 -272
WIRE 272 -16 64 -16
WIRE 400 -16 400 -64
WIRE 400 -16 336 -16
WIRE 432 -16 400 -16
WIRE 576 -16 432 -16
WIRE 784 0 784 -48
WIRE 864 0 784 0
WIRE 432 32 432 -16
WIRE 784 48 784 0
WIRE 64 96 64 -16
WIRE 160 96 64 96
WIRE 304 96 240 96
WIRE 1072 112 1072 32
WIRE 64 128 64 96
WIRE 432 160 432 112
WIRE 784 176 784 128
WIRE 64 224 64 192
WIRE 160 224 64 224
WIRE 304 224 304 96
WIRE 304 224 240 224
WIRE 640 224 640 32
WIRE 880 224 640 224
WIRE 928 224 928 48
WIRE 928 224 880 224
WIRE 64 256 64 224
WIRE 928 304 928 224
WIRE 64 352 64 320
WIRE 160 352 64 352
WIRE 304 352 304 224
WIRE 304 352 240 352
WIRE 640 352 640 224
WIRE 640 352 304 352
WIRE 64 384 64 352
WIRE 928 464 928 384
WIRE 64 480 64 448
FLAG 432 160 0
FLAG 928 464 0
FLAG 64 480 0
FLAG 1072 112 0
FLAG 784 176 0
FLAG 880 224 OUT
SYMBOL res 256 368 M270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R1
SYMATTR Value 470
SYMBOL res 256 240 M270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R2
SYMATTR Value 4700
SYMBOL res 256 112 M270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R3
SYMATTR Value 47k
SYMBOL cap 80 384 M0
SYMATTR InstName C1
SYMATTR Value 100n
SYMBOL cap 80 128 M0
SYMATTR InstName C3
SYMATTR Value 1n
SYMBOL cap 80 256 M0
SYMATTR InstName C2
SYMATTR Value 10n
SYMBOL npn 720 -144 R0
SYMATTR InstName Q2
SYMATTR Value 2N2222
SYMBOL voltage 1072 -64 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 20
SYMBOL res 416 16 R0
SYMATTR InstName R5
SYMATTR Value 470k
SYMBOL pnp 576 32 M180
SYMATTR InstName Q1
SYMATTR Value 2N3906
SYMBOL npn 864 -48 R0
SYMATTR InstName Q3
SYMATTR Value 2N2222
SYMBOL res 624 -240 R0
SYMATTR InstName R6
SYMATTR Value 220k
SYMBOL res 768 32 R0
SYMATTR InstName R7
SYMATTR Value 4700
SYMBOL res 912 288 R0
SYMATTR InstName R8
SYMATTR Value 1000
SYMBOL res 384 -160 R0
SYMATTR InstName R4
SYMATTR Value 470k
SYMBOL cap 336 -32 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C4
SYMATTR Value 100n
TEXT 728 480 Left 2 !.tran 100m
TEXT 400 432 Left 2 ;EPW SED OCT 2024
TEXT 304 480 Left 2 ;VOLTAGE FOLLOWER RC OSC
piglet