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From: KevinJ93 <kevin_es@whitedigs.com>
Newsgroups: sci.electronics.design
Subject: Re: Random thoughts on sinewave oscillators
Date: Sat, 19 Oct 2024 12:46:35 -0700
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On 10/19/24 12:13 PM, piglet wrote:
> 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.
> 
<...>
> piglet
> 

If you move the ground to the emitter of Q3 and slide R8 through the 
power supply to the collector of Q3 you can see that it is a 
conventional phase shift oscillator with feedback from the output of an 
inverting amplifier via a 3-stage RC network.

kw