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Re: gEDA-user: challenge board ALMOST works

On 9/12/06, Dan McMahill <dan@xxxxxxxxxxxx> wrote: 

John Luciani wrote:
> On 9/12/06, Dan McMahill <dan@xxxxxxxxxxxx> wrote:
>> al davis wrote:
>> > On Tuesday 12 September 2006 22:32, Dan McMahill wrote:
>> >>  Some TV's used injection locking
>> >> for some of the sync circuits.
>> >
>> > All of them, back in the tube days.
>> >
>>
>> Oh, and I forgot one which John should appreciate.  Isn't the pitch
>> oscillator on a theremin usually tuned to injection lock when you move
>> away from the pitch antenna?  I could be wrong about this one.
>
> To be able to play low notes I believe you want to avoid locking since
> when you lock the output of the mixer will be at 0Hz.

I thought they were supposed to injection lock at the very low end to
avoid a wierd tone when you're away from it and also to help avoid
wrapping back to higher pitches  as you move further away.  I'll have to
dig out my theremin folder if I can find it.


As long as the frequency of the variable oscillator is very close to
the frequency
of the fixed oscillator it shouldn't matter if they injection lock. If they lock
at the low end that would be nice. Depending on the layout and the design they
probably do lock. After this discussion I will have to go my cellar and checkout
the low-end performance ;-)

If you find anything on this, in your theremin folder, please send it along.

Of course you've built one and I haven't which counts for a lot! 

Actually one of my kids did a PCB layout of the Moog Etherwave. I had some
space on a PCB panel so I decided to quickly convert it to SMD. I also
added a Maxim
amp and a switching supply (and a case shaped like an eighth-note).

I haven't played with it much. For me it is an awkward interface. If I
want to control
the pitch of sinewaves I would rather play my MiniMoog ;-)

(* jcl *)

--
http://www.luciani.org


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