StompFLO & OneShot in a box

[Matthew Sanford]

They were hammered on solder fumes! I was trying to not mix vertical into them getting horizontal, but that jumper round the corner between ic and cap did need some light literal hammering...

I'm a little concerned as the LFO reaches just over 5.5v, as I want to use it on the PIC chips too, but I figure changing the 100k to 1M will get it to 5.05v

[ElectricDruid]

I'm a little concerned as the LFO reaches just over 5.5v, as I want to use it on the PIC chips too, but I figure changing the 100k to 1M will get it to 5.05v

Can we see the final schematic for this so we can see if we agree, please?

[Matthew Sanford]

Sure! Only thing missing is the 100n across the lm358 power, but otherwise complete



And Duck, the IC socket wipes...you mean the soldering? I know in adding the cap on bottom I found a not quite complete one I reworked, but likely there are others. Is that what you meant?

[ElectricDruid]

Ok, so you're talking about changing R4 to reduce the gain on that filter stage, right? That should work. Personally, I'd probably reduce R3 to 1K rather than boost R4 to 1M, but that's just me.

Duck was talking about the IC sockets. Some of the leaves look a bit bent and beaten up, so they may not be entirely reliable.

[Matthew Sanford]

Big pack of cheap ic sockets that there was, so I guess that's how they go. And I'll go with your suggestion, I have tons of 1ks, 10ks, and 1Ms, ...maybe I need to get the 100k decade in a plethora package too. Still, lower value, lower noise additions, right?

When I get to the PCB, I am planning 2 layer with ground plane across the bottom - should I put it in two with a thin dividing line to keep all StompLFO stuff on one and all LM358 on the other, then merge them to the power ground at the points between the caps as on the schematic? I still gotta practice with KiCad a bit more to get it going right, figured prototype first - and am thinking for small ones to put the TRS and pot together with outs in potentiometer formation, may be able to lay it on the druid boards (and other board mount thing) with spare pins to join it...

[ElectricDruid]

Big pack of cheap ic sockets that there was, so I guess that's how they go.

Yeah, pretty much. I use those same ones for all my prototypes because (a) I don't want to spend a lot on something that's only a prototype, (b) I don't expect to be using it heavily for years, and (c) if it works with that, it'll be fine when anyone builds it with something better!!

And I'll go with your suggestion, I have tons of 1ks, 10ks, and 1Ms, ...maybe I need to get the 100k decade in a plethora package too. Still, lower value, lower noise additions, right?

That would be my feeling. It's worth saying that my basis for this is only one experiment I did decades ago when I was a teenager learning about the 741. It looked like you could make an inverting amp with unity gain using any values you liked, as long as they were the same. I tried a load of different values on the breadboard, from about 1K up to 1M. I found out they were all the same, except the 1M was noisier. Since then, I mostly try and stay in the 10K-100K decade. Less than that starts to eat more current which you don't generally want in a pedal (and certainly didn't back then with old blue EverReady - yeah right!! - 9V PP3's) and more gets noisy. If I was building a mixing desk, I'd use a big power supply and maybe take a factor of ten out of everything - but I'd have a ton of other stuff to learn then too!

When I get to the PCB, I am planning 2 layer with ground plane across the bottom - should I put it in two with a thin dividing line to keep all StompLFO stuff on one and all LM358 on the other, then merge them to the power ground at the points between the caps as on the schematic? I still gotta practice with KiCad a bit more to get it going right, figured prototype first - and am thinking for small ones to put the TRS and pot together with outs in potentiometer formation, may be able to lay it on the druid boards (and other board mount thing) with spare pins to join it...

Something like what you describe sounds good. Keep the analog and digital grounds separate back to the power input if you can. In Kicad or other PCB packages, this probably involves having two separate grounds defined, and then providing a method to connect them. If you tell the software that they're connected, it thinks they're all one thing (which they sort-of are, but at the same time *not*) and then it won't let you do stuff like flood fill the two ground planes independently.

HTH

[Matthew Sanford]

Ok, good advice. I might need some traces on the backside interrupting the planes, but am going to try to keep that minimal and short if done. I guess the whole power conditioning rail will have its ground rail in the ground plane, but maybe I can have just that line on the top tied in to the appropriate places.

The other thing I was thinking on is it could be good to make the prospective 1k Rf into a 100k pot so it could adjust to needed LFO voltage levels, like 3.3v for the digi-delay...would be nice to have a meter on it to know what you're getting, maybe one led per volt, but that needs more thinking...otherwise something in between with options to change voltage, splitter, etc

[Matthew Sanford]

Ok it's been awhile and I'm not done, putting off board on the third version prototype Vero and hoping it works correctly, but the schematic is done so I wanted to share it. Caveat, the vactrol/led clr shows 270 but really should be 48 for two greens, and as I'm omitting the status leds will be 180 for the prototype. Later I'll want variable there to manage higher incoming CV (or variable gain on the LM358 it comes in through, better idea).

I recently found GameChanger Audio is now doing this but smarter with digital control of each level, etc, but mine should be pleasing too!

Have to thank all those that brought me this far in these posts and others

https://www.diystompboxes.com/smfforum/index.php?topic=131651.0


https://www.diystompboxes.com/smfforum/index.php?topic=130942.0

https://www.diystompboxes.com/smfforum/index.php?topic=131560.0

https://www.diystompboxes.com/smfforum/index.php?topic=131517.0

Anyway, the scheme

[Baran Ismen]

I have done this merging project recently, and here's my project, maybe it would help to some extent. It's mostly the same layout on the datasheets, but I've added a switch to swap StompLFO and OneShot, an LFO led, and also added another internal one for the TRS-RTS switch and an external trigger input for Tap Tempo which I plan to add an Arduino-based BPM counter and trigger it with it. There's also a PCB I've designed for it if you're interested.

Huge thanks to Druid/Tom for suffering my maybe the most basic questions

[Matthew Sanford]

I have done this merging project recently, and here's my project, maybe it would help to some extent. It's mostly the same layout on the datasheets, but I've added a switch to swap StompLFO and OneShot, an LFO led, and also added another internal one for the TRS-RTS switch and an external trigger input for Tap Tempo which I plan to add an Arduino-based BPM counter and trigger it with it. There's also a PCB I've designed for it if you're interested.

Huge thanks to Druid/Tom for suffering my maybe the most basic questions

I do like what you did with the Fortune Wheel. I had wanted to switch the two originally but with the CV controls set differently for each when you switch, but...too much at the time, job for a PIC or too many pots. With yours having 3.3v, you could set the switched off chip through a momentary to influence a factor in the on chip, of course would need to be by the tap if One-Shot was the off chip. I wanted to make it capable to handle many different circuits, planned to use vactrols for separation on all pots, so buffered in current amps (thanks Diffeq), inverted so I could use it on pots as voltage dividers or different directions on rheostat ones, set it to have outside LFOs turn its pots, then a triangle w/buffer & inverter in-pedal too... now planning the in-pedal LFO w/buffer&inverter on all the pedals so they can be screwy on their own or have the Druid influence plugged in. Aside from the anxiety of learning as I design, insistent ideas like a circuit to create a square wave from the LFO with division to sync timing on various things, output panner on multiple effect chains, one to increase/decrease LFO voltage range, effect order switching (imagine the delay at the end of the chain catching everything before going to the start and echoing it back through everything!). The madness...

I tell you though, Tom and so many others here give freely of their time and knowledge, and I will never be able to thank these amazing folks enough! Do gotta work programming though, Gamechanger Audio's way of digital control instead of extra pots and switches is a pipe dream I'd like to make reality.