Triggering the ONESHOT chip

[strungout]

Hey.

So, I have this working (without the audio out part):



And the ONESHOT working (touching ground triggers the event): https://electricdruid.net/datasheets/ONESHOTDatasheet.pdf

Now I'm wondering how to connect both of these together. I need something that'll ground the signal when I play a note... Help?! Maybe it's obvious, but not to me!

Started with an envelope follower but that didn't work.
With the signal-to-gate, I tried an inverting stage before the oneshot, through the 3904 on the datasheet, directly into the chip... I guess I need to get my led bright and then going dark when I strum? Indicating that the signal goes to 0V...

Not sure what I'll do with it, but I'll find something.

[Matthew Sanford]

I'm confused, what is the ONESHOT going to do to that circuit? And how is that related to you wanting to mute the guitar? Are you trying to use the ONESHOT to mute it, because I took what you wrote just as the guitar muted when you play...or have the one shot cut your signal?

[ElectricDruid]

It's simple, Frank!

You've got a Gate output from the MFOS circuit, and that can be fed directly to the Trigger input on the datasheet circuit. That trigger input uses a 2N3904 NPN to switch on and provide the short-to-ground action the chip wants to see.

Just connect one circuit to the other and off you go. It really is that easy.

[strungout]

@ Matthew: Sorry I was kind of thought streaming there... The MFOS circuit turns the guitar signal into a gate, which triggers the ONESHOT, which then triggers its event, which then modulates whatever I'm gonna end up putting at the end of it (tremolo, phaser, flanger, etc.) The LEDs are there just to show me whether the circuit sections are working.

Ok, so I'm getting blind... I found that I was connecting a jumper just one hole too far, instead of the output of the MFOS. Sigh... 

I tried what you said, Tom, but the transistor seems to get in the way somehow. It does work when I bypass it and connect it directly to the ONESHOT, but it (predictably) triggered it only after I muted my strings. Simple fix, I had one free opamp from the TL074 I'm using and I just inverted the signal so the ONESHOT now triggers when I start playing. Still won't work if it goes through the 3904... I switched out the components but no change... Hmmm...

But it works!

[ElectricDruid]

I tried what you said, Tom, but the transistor seems to get in the way somehow. It does work when I bypass it and connect it directly to the ONESHOT, but it (predictably) triggered it only after I muted my strings. Simple fix, I had one free opamp from the TL074 I'm using and I just inverted the signal so the ONESHOT now triggers when I start playing. Still won't work if it goes through the 3904... I switched out the components but no change... Hmmm...

Perhaps if you take the 10K volume trimmer off the end of the MFOS circuit? The 10K on the base of the 2N3904 in the trigger input circuit provides enough protection for much bigger gates than 9V, so there's no need to cut the volume down. Also make sure you've got the didoe the right way around! (Although in this case you shouldn't need it - it protects the transistor against negative voltages on the input, but with the input hardwired to a source that can't go lower than ground, it should be fine without it.)

But it works!

That's the important bit!

[strungout]

So, upon further experimentation, it seems the circuit likes a cap  in series between the gate output and trigger input. It works. I used 47nF. 10nF is too low. AND I don't have to invert the signal with that cap in between.

I'm not using the trim. Took it out earlier, in my attemps to get things working and have the fewest amount of things to fiddle with every time XD

Now, to think of something to use it with...