> Is it possible to mod the A143-9 to have an external sync input
> I love this thing, but the one thing it's missing for me is a
> sync (reset).

I'm sorry but that's not possible. We thought about this feature during the
design but the circuit is kind of a filter in self resonance. If one would
add a sync circuit similar to other VCOs (electronic switch that discharges
the timing capacitor) the oscillation would not start with full amplitude
but increase little by little until the full level is reached. That's
probably not what you would expect from a sync input.

Best wishes
Dieter Doepfer