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From: "Edward Rawde" <invalid@invalid.invalid>
Newsgroups: sci.electronics.design
Subject: Re: Final final 1kHz oscillator
Date: Wed, 27 Nov 2024 21:25:55 -0500
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"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vi7cks$26f3$1@dont-email.me...
> On 27/11/2024 7:48 pm, JM wrote:
>> On Tue, 26 Nov 2024 15:32:38 +1100, Bill Sloman <bill.sloman@ieee.org>
>> wrote:
>>
>>> On 25/11/2024 1:02 pm, Bill Sloman wrote:
>>>> On 24/11/2024 5:10 pm, Edward Rawde wrote:
>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message
>>>>> news:vhue9h$243sl$1@dont-email.me...
>>>>>> On 24/11/2024 5:11 am, Edward Rawde wrote:
>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message
>>>>>>> news:vhs1ea$1kbt4$1@dont-email.me...
>>>>>>>> On 23/11/2024 4:12 pm, Edward Rawde wrote:
>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message
>>>>>>>>> news:vhrma8$1io30$2@dont-email.me...
>>>>>>>>>> On 23/11/2024 3:32 am, Edward Rawde wrote:
>>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message
>>>>>>>>>>> news:vhp713$12bnt$2@dont-email.me...
>>>>>>>>>>>> On 21/11/2024 1:00 am, Bill Sloman wrote:
>>>>>>>>>>>>> On 20/11/2024 2:03 pm, Edward Rawde wrote:
>>>>>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message
>>>>>>>>>>>>>> news:vhjj2v$24eu4$3@dont-email.me...
>>>>>>>>>>>>>>> On 20/11/2024 1:29 pm, Bill Sloman wrote:
>>>>>>>>>>>>>>>> On 20/11/2024 12:59 pm, Edward Rawde wrote:
>>>>>>>>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message
>>>>>>>>>>>>>>>>> news:vhibce$1t7v2$1@dont-email.me...
>>>>>>>>>>>>>>>>>> On 18/11/2024 2:58 pm, Edward Rawde wrote:
>>>>>>>>>>>>>>>>>>> "JM" <sunaecoNoChoppedPork@gmail.com> wrote in message
>>>>>>>>>>>>>>>>>>> news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
>>>>>>>>>>>>>>>>>>>> On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
>>>>>>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>> "JM" <sunaecoNoChoppedPork@gmail.com> wrote in message
>>>>>>>>>>>>>>>>>>>>> news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
>>>>>>>>>>>>>>>>>>>>>> On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
>>>>>>>>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote:
>>>
....
>>
>> When evaluating architecture there's little to be gained by using a
>> complicated opamp model.  Use a simple 1 or 2 pole model to begin
>> with.
>>
>> Try the attached file, I've used a simple model to speed up the
>> simulation, and made a slight circuit change.  This shows the
>> harmonics due to the control loop to be sub 130dBc.  Of course the
>> amplifier harmonic distortion is not simulated, but neither was it in
>> the simulation by Mr Rawde.
>
> Thanks for that. I've got it into a form that my copy of LTSpice recognises as a .asc file, so I have looked at it.

I get 140dB down at 2kHz, 130dB down at 3kHz

>
> I haven't run it yet because I'm running yet another variant of the circuit, which has got to 2.4 seconds, and I'll leave it 
> running overnight.
>
> I'm currently curious about the effect of the phase of the 2kHz component in the control signal (coming from my full-wave 
> rectifier), and a fast simulating version of the circuit is just what I need to get that sorted out. I had thought that that it 
> would be trivial to get the phase right, but my first attempt didn't get close.
>
> I could go mad and put a version of the circuit into KiCad and create a printed circuit layout and get some Chinese firm to make 
> and load the board.

I could too but I already know what 1kHz sounds like and I doubt that my ears can tell the difference between harmonics 120 and 
130dB down.

>
> It would be an extravagance, but nothing dramatic.
>
> -- 
> Bill Sloman, Sydney
>