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From: "Edward Rawde" <invalid@invalid.invalid>
Newsgroups: sci.electronics.design
Subject: Re: An actual circuit
Date: Fri, 24 May 2024 14:41:02 -0400
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"bitrex" <user@example.net> wrote in message 
news:6650d62f$0$2363134$882e4bbb@reader.netnews.com...
> On 5/24/2024 2:00 PM, bitrex wrote:
>
>>> Yes, it is mysterious. Set both drain resistors to 3.3K and zoom way
>>> up on the two source voltages for the first 20 seconds.
>>>
>>> LT Spice may have some hidden asymmetry. It has to do math
>>> sequentially, maybe.
>>>
>>> In real life, parts will be plenty asymmetric. Especially jfets.
>>>
>>
>> There are bunch of variants of this circuit, I call it the "Forest Mims 
>> Oscillator" cuz in one of his radio shack circuit books was where I first 
>> remember seeing it as a teenager.
>
> I'm pretty sure he didn't invent it though and that I've seen it in books 
> from the 60s also, it was probably invented about 5 minutes after the PNP.

Rufus P Turner's FET circuits is probably where I got the doing it with FETs 
idea from.
It's on page 50 and easy to find a pdf.
It also says the RC circuit should matched to within 1% but not sure why.

I've not previously seen it with source resistors.
The idea of not connecting the sources to ground came about because I didn't 
want the LED drive to affect the RC circuit.
So in my teens I just connected the source directly to the transistor base 
with no other component and put the LED current limiting in the collector 
circuit.

>