[sdiy] LFO extension?

[Mountain Man]

Seems reasonable (and thanks!).  Based on this, I spent a fair amount of
time over the weekend fooling with 555 circuitry.  Didn't get the
monostable circuit with input pulse longer than output pulse, triggered
off falling edge to work completely, although parts of the circuit work,
and I've learned some :)

Anyway, I decided this circuit isn't *really* what I want anyway!  If
I'm going to need a separate trigger circuit anyway, I might as well
have something that will run off of any sort of input waveform.  Ideal
would be a circuit will trigger (with a short pulse) whenever the input
wave rises about a certain voltage, with that voltage level adjustable.
Even better would be the ability to select trigger on rise only, or
trigger on both rise and fall, with same voltage level used for trigger
on fall as on rise.  Anyone have a circuit like this?

Thanks,
Elby

Scott Gravenhorst wrote:

> A 555 timer (poss. the CMOS ver ICM7555) set up as a _monostable_
> with a very narrow pulse width (this can be programmed with
> a resistor).  This would be triggered by the LFO's square output.
> This is one of the very things this chip is designed for.  The
> basic setup for this is in the app notes for the 555, possibly
> also the spec sheets for it (all available on the net).  This
> will give one pulse per full square cycle.
>
> Mountain Man <mtman at cloud9.net> wrote:
> >I'm interested in adding an additional "dedicated" output from
> >the EFM sbm LFO to control a sample/hold. I'd like it to have a
> >fixed (narrow) pulse, and a rate that matches the current square
> >and sawtooth outputs. Is it possible to modify this circuit to
>
> -- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
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