[sdiy] reset circuit for LFO

[Danjel van Tijn]

A while ago I posted asking for advice on modding a Livewire Vulcan
lfo so that it could be reset.
Amos suggested using a CD4053 switch to control the timing cap being
shorted to ground temporarily to cause a reset.

As first experiment I had two wires: one to the timing cap and one to
ground. Whenever I connected these together temporarily it
successfully reset the LFO.

Next step was  wiring up a little board with the switch circuit. The
reset jack was connected to one of the control inputs of the cd4053 so
that a short pulse would temporarily connect the LFO timing cap to
ground.

So far it kind of works but not well:  If I feed at an LFO squarewave
from a Plan B ELF LFO  it holds the Vulcan in reset while it is high
and then allows it to cycle when it is low. However when I switch to
the alternative narrow pulse square waveform the pulses seem to be too
short to cause a reset.
Also when I connect a midi2cv converter and generate clock pulses or
gate signals they are unable to cause a trigger.

Right now the 4053 is being powered by the 12V rail... should I be
using a lower voltage so that the logic signals from other devices
like my midi2cv can actually drive the 40530 controls? i.e. Should I
run it at 5V instead?

Do I need any kind of trigger conditioning off of the reset jack?
e.g. filter? schmitt trigger?

cheers,
Danjel