[sdiy] Re: reset circuit for LFO

[Danjel van Tijn]

Someone suggested using the circuit that Ken Stone used on the clock
input here: http://www.cgs.synth.net/modules/cgs13v2_gated_comparator.html

A comparator with a diode like this might help me out.



On Mon, Oct 19, 2009 at 8:16 AM, Danjel van Tijn <danjel at gmail.com> wrote:
> 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
>