[sdiy] 555 vco success

[Jim Patchell]

Scott Gravenhorst wrote:

> Excellent!  When something you made works, it's a total
> thrill, is it not?  Now you can play with it!
>
> Interesting that they don't soft synch.  I 'measure'
> how close together the VCOs are tuned before synching
> by getting them  as close as possible and then timing
> how long it takes the phasing sound to repeat.  Someone
> correct me if this is wrong, but if that phasing sound
> takes one second to complete, the oscillators are
> detuned by 1 Hertz.  If it takes 5 seconds, then they
> are at 0.2 Hz apart (1/5 Hz), etc. This is how I determine
> what resistance to soft synch the circuit has.  The smaller
> the number of Hz, the better.
>

    This is what I do.  For the VCO's I did, I found that 10 seconds was about
the limit.  This was due to the fact that the frequency stability beyound this
point made it difficult to do a measurement.  I figured if they don't softsync at
.1hz difference, it may not make any difference anyway.

    -Jim