John Luciani wrote:
> 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 ;-)
Here we go... Do you have the manual for the etherwave? Last paragraph
of the left column of page 6. Basically the 2 caps which combine the
fixed frequency oscillator and the variable frequency oscillator for the
pitch circuit not only combine the signals into the mixer, they also
couple the oscillators so that they will injection lock to get a stable
"zero beat" when you step away from the theremin.