Taplfo questions.

[digi2t]

Excellent!! Thanks again Tom!

[digi2t]

Got the StompLFO chips last week, had a nice quiet Sunday to breadboard and noodle with it. It works perfect!! Everything I was hoping to get out of it, and more. IMHO, Spaceman missed the boat on this one. This baby should have been in the Explorer, rather than the custom job they have in there now.

Just one question on the tap tempo...

From what I found in my noodling, the tap tempo was a bit hit or miss at first. I tried 2, and then 3 taps, and often times, it would revert to the pot speed and a couple of seconds. It could well be because of the breadboard (noise, poor connections, poor quality switch etc). I was using a cheaper momentary switch, a type that clicks when making contact, it wasn't really working well. I swapped it for a better quality soft touch switch. That helped a lot, but still not perfect. The occasional tap would revert to the pot speed. On a lark, I decided to try a 100n cap on pin 4 to ground, perhaps an effort to filter or smooth out the signal. Lo and behold, it worked quite well. Every 3 tap I would put in would change and stay in that tempo. External +5v tap input works perfect too.

Was using a 100n cap here a good choice? Is it actually doing something? Or, is it pure luck that it's working this well with the cap?

[ElectricDruid]

Ok, it works like this:

Both StompLFO and the TapLFO measure the time between *pairs* of taps. If you tap four times, you get the time between the second pair. You'll get tempo of the the first pair, and then rapidly updated by the second pair.

When the first tap arrives, a counter is started, and the waveform is reset to the beginning - mostly that's the "top".
When the second tap arrives, the counter is stopped and the new tempo is calculated. If you tap an odd number of times, including once only, that counter will overflow (which takes either 2 or 4 seconds, I think - I can't remember without reading the code) and the chip resets without changing the tempo. This is handy since it allows you to use a single tap to get the waveform back in time if it starts to drift out.

It should carry on using the tapped tempo until it detects a change on the Tempo(Rate/Freq) CV. There's a small threshold and if the knob moves more than that, it goes back to the pot setting - you must have tweaked it. However, this can sometimes play up if you've got wobbly pots or a bad power supply (which makes all the voltages go up and down!).

Final thing to say is that the tap tempo input expects a short-to-ground signal like a momentary SPST switch from the pin to ground. It's tied high internally by a pull-up. Trying to trigger it by taking the pin high does weird stuff if it does anything at all.

Ok, hope all that helps you figure it out!

[digi2t]

So, a big shout out to Tom here. Thanks man!! The StompLFO chip works like magic. It took the boring 'ole Spaceman phaser, and really juiced it up. The project wasn't without a couple of set backs though. A bad stomp switch had me up a tree for a while with the Mill2 bypass (LED would turn off), and then the Eagle template for the rotary com pole was off a smidge, enough so one could install the switch with all the other poles offset one spot. Anywho, finally got it sorted and boxed. It's friggin' awesome!

[garcho]

^ nicely done! bravo

just got a CEM3320 filter on the breadboard with a STOMPLFO, and another STOMLFO controlling the first one. Too much fun! And one tenth of the real estate...

[Invertiguy]

So, a big shout out to Tom here. Thanks man!! The StompLFO chip works like magic. It took the boring 'ole Spaceman phaser, and really juiced it up. The project wasn't without a couple of set backs though. A bad stomp switch had me up a tree for a while with the Mill2 bypass (LED would turn off), and then the Eagle template for the rotary com pole was off a smidge, enough so one could install the switch with all the other poles offset one spot. Anywho, finally got it sorted and boxed. It's friggin' awesome!

My body is ready...

[digi2t]

My body is ready...

Yes, young grasshopper... but will your mind follow?

[ElectricDruid]

^ nicely done! bravo

just got a CEM3320 filter on the breadboard with a STOMPLFO, and another STOMLFO controlling the first one. Too much fun! And one tenth of the real estate...

The thing I like about using one StompLFO to control another is that the "Offset" control on the first one handily replaces whatever control on the other one that you fed it to in the first place, so you can add optional modulation of one of the parameters without losing the basic control.

Say you're using StompLFO A to control the depth of StompLFO B. The Offset control of StompLFO A now becomes the "Depth" control of StompLFO B, and you just feed the output of StompLFO A to the Depth CV input of StompLFO B. It's dead simple.

I hadn't realised this possibility when I wrote it that way. I was intending that the offset would be used to make bias adjustments simpler, but when you're controlling 0-5V stuff, you can just use it directly to produce a CV. Really handy.

[Mr. Lime]

Sorry for being a litte off-topic but controlling one Stomplfo with another one got my attention!

I'm thinking about the Lovetone Ring Stinger (Dino's String Ringer) and it's LFO controlling the VCO.
If this would be adaptable to a Ring Modulator things are going crazy with less parts needed!

Are we able to get the same response from a Taplfo 3 controlled by a Stomplfo?

[ElectricDruid]

The TapLFO is still an LFO not a VCO, so the frequency range won't go nearly as high. I don't know what frequency range the String Ringer's VCO covers. Did a few searches, but can't find a specification anywhere.

You're right though - it's an ideal application for a PIC. You've got a relatively simple audio path, and then a *lot* of other circuitry to basically generate some modulation waveforms. You could wrap all of that LFO+VCO up into a single chip for sure. That'd take some custom coding though (but I'm definitely filing that idea!).
With stuff that I've got *right now*? You could get close with a StompLFO and a VCDO. The waveform-scanning ability of the VCDO would give some truly wild outputs. I've never heard a ring mod with a wavetable VCO fed into it before...
The rest of it would be the same. Input booster, diode-ring-modulator with coupling transformers, output buffer, some switches to connect it all up.

[Mr. Lime]

I thought the multiplier of the TapLFO might get's us in the right VCO range but that's just loud thinking..


Anyway the VCDO looks promising as well! Probably the easiest way would be to get a CGS67 - Active Real Ring Modulator and a Waverider VCDO MkII PCB set and stick them together. Isn't it?
https://modularaddict.com/media/catalog/product/cache/1/image/1100x1100/9df78eab33525d08d6e5fb8d27136e95/c/g/cgs-cgs67x-pcb.jpg
http://www.frequencycentral.co.uk/wp-content/uploads/2011/09/scan0002.jpg

[ElectricDruid]

Yep, that'd do it! 

Watch out for the +/-12V power supply requirement if you try it.

[Mr. Lime]

Alright thanks!

Back thinking about the Calypso Phaser. A/DA's Final Phase sweep modulation seems awesome. Isn't this something like a modulated offset control or how would this effect be archived?
I'm sure the STOMPLFO offers options for that..

[ElectricDruid]

Alright thanks!

Back thinking about the Calypso Phaser. A/DA's Final Phase sweep modulation seems awesome. Isn't this something like a modulated offset control or how would this effect be archived?
I'm sure the STOMPLFO offers options for that..

I hadn't seen the Final Phase, so thanks for the pointer. Looks like a nice box. They're pretty vague about what exactly the "Sweep Modulation" is doing. The best I found was this:

"SWEEP MODULATION
A Variable speed oscillator that adds to or modulates the main sweep, producing shimmering, vibrato-like effects, asymmetrical sweep patters, multiple phaser effects, modulated sweep, syncopated beats, etc."

So that sounds like a second LFO modulating the rate of the first one to me. Bonus points if there's feedback from the first one to the second one too. Try a pair of StompLFOs with (some amount of) the output of each fed to the Rate CV of the other. But to be honest, the Random Slopes waveform gets you some of the way there with a single chip.

[Mr. Lime]

Great and thanks for your comments on this.
So I rather focus on modulating the rate control. I have a sequencer laying around which I could use for the start..

A schematic of the Final Phase can be found here:
https://lectric-fx.com/wp-content/uploads/2017/06/Countdown-Phaser-V.1.0.pdf

Looks like I have to get myself a Calypso phaser from deadendfx soon.. 
Imagine a Bi Phase with two StompLFOs! muahahaha