[sdiy] Buchla 144 dual square wave oscillator

[Scott Gravenhorst]

Donald Tillman <don at till.com> wrote:
>   > From: "Jerry Gray-Eskue" <jerryge at cableone.net>
>   > Date: Fri, 26 Jun 2009 13:53:58 -0500
>   > 
>   > Complements, this is a nice detailed analysis.
>
>Thanks.
>
>   > So I take it that the flip-flop is a Toggle type providing a
>   > divide by 2 of the oscillator frequency?
>
>I was going to suggest Wikipedia..., but man, the Wikipedia Flip Flop
>page is confusing mess.
>
>The flip flop here has two transistors, and two stable mirror-image
>states that it can be in -- each state has one transistor on and one
>transistor off.  A single pulse input causes the flip flop to switch
>from one state to the other.  Hence the name "flip flop".  And so a
>flip flop will convert a string of pulses into a square wave.
>
>And since two state changes make a square wave, yes, it will divide
>the original frequency by two.
>
>Don Buchla could have just squared up the original sawtooth wave, but
>he probably went to the trouble of using this approach so he could be
>assured of of having a 50% duty cycle without any trimming.  Hence the
>"square wave" in the title of the module.

This is exactly what I was thinking.

I thought the diode inputs were interesting, I realize that this is an old
technique, but in this circuit, it's sort of elegant IMO.  I'm so used to a D flop
or a JK flop being used as a toggle flop that I smiled when I saw those diodes and
realized what they did.

And thank you Don, for that operational breakdown you posted.

>  -- Don
>
>-- 
>Don Tillman
>Palo Alto, California
>don at till.com
>http://www.till.com
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>

-- ScottG
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-- Scott Gravenhorst
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