MULTIFLANGE Chip for Wah-LFO?

[Zwachi]

Hi folks!

Having a Dead Astronaut Tremshifter on the working bench, I was thinking about replacing the LFOs with the MULTIFLANGE chip. This offers 7 waveforms and a manual mode which would be cool in combination with an expression pedal for foot controlled wah wah effects. Same for the tremolo part in the circuit to get some kind of volume pedal in manual mode.

Chip: https://electricdruid.net/wp-content/uploads/2016/05/MULTIFLANGEDatasheet.pdf
Tremshifter: https://docs.wixstatic.com/ugd/ff4c6c_4b0cda100ed6495eb32905a0c076b703.pdf

Can I simply use the clock outputs to drive the vactrols?
The TAPLFO has got a PWM output with 19.5 kHz but the clock output has 20 MHz.

Is the clock output on the MULTIFLANGE suitable for driving LEDs?

Thanks a lot!

[ElectricDruid]

Yes, you can drive LEDs from the MULTIFLANGE clock outputs, since the PIC IO pins will sink/source up to 20mA of current, I think. Enough for a modern LED, anyway.

However, the MULTIFLANGE output is a high frequency *clock* signal that varies up and down in *frequency*, not a PWM signal that would make sense as an LFO. You'll find if you try it that you don't get anything happening, because whatever clock frequency it outputs, the duty cycle is still 50/50%. (It might work driving a switched-capacitor filter)

Instead, you should try the STOMPLFO chip. This basically the LFO part of the MULTIFLANGE (8 waveforms, similarly). It'll drive the LEDs directly and would be a great fit with Astronaut's Tremshifter. The chip has a "Offset" control which would be ideal for your expression pedal - just turn the depth down to zero and waggle the offset to sweep the whole range. Or leave the depth above zero and do a bit of both, expression pedal with LFO modulation on top.

[Zwachi]

Hi Tom!

Thanks again for your quick response. I seemed to miss the offset control on the STOMPLFO which looks awesome on paper! Always thought this would be a simplified version of the TAPTEMPO chips but this gives extra versatility. Now I have to thing if I had to take advantage of the tap function as well. 

Alright I will give this a try, how do you recommend to implement those chips best? They have a different pin layout than dual ICs and need regulated 5V power supply. Veroboards or what's the usual way therefore?

The vactrols should be fine with the passive filter for 0-5V output swing?

[ElectricDruid]

It's dead easy to get it running. You do need a 5V supply, but that's just a 78L05 and a couple of caps. The pots can run direct to the CV inputs on the STOMPLFO. If you're driving an LED for a vactrol, you don't need any filter at all. In fact, it's better without it, since the best way to drive an LED for variable brightness is by varying the on/off period, rather than by messing with the current, or (even worse) the voltage.
You can certainly do it on veroboard. My prototypes were done on stripboard. In fact, you can grab a fe pointers from this thread:

https://www.diystompboxes.com/smfforum/index.php?topic=119927.0

I used a transistor to drive the LEDs because I was using two vactrols and an LED, but for a single vactrol you won't need to bother.

[Zwachi]

Sounds great.

Actually it would be nice to drive a pair of indicator LEDs to show the modulation speeds. The additional transistors should not be too much of a pain. 

So for LED based modulation effects the STOMPLFO is to prefer but on chorus or delay effects based on BBD chips the MULTIFLANGE should be the weapon of choice to keep it simple?

Just want to make sure I won't miss something in my next order.
That's what I got so far:

[thermionix]

^I would like to know more about your Cliff branded 3PDT.  Is that an actual UK-made item, or a Taiwanese part?

[ElectricDruid]

Actually it would be nice to drive a pair of indicator LEDs to show the modulation speeds. The additional transistors should not be too much of a pain. 

You'll only need one transistor. The current handling of a single transistor is easily sufficient for several LEDs.

So for LED based modulation effects the STOMPLFO is to prefer but on chorus or delay effects based on BBD chips the MULTIFLANGE should be the weapon of choice to keep it simple?

Exactly. The MULTIFLANGE is (pretty much) a STOMPLFO modulating a Clock VCO rolled up into a single chip, avoiding the need for a MN3102 BBD "Driver". If you don't need a high frequency VCO output, stick with the "raw" STOMPLFO.

That's what I got so far:

Lol! This is getting out of hand already. Couldn't you find any furry knobs?!

[Rob Strand]

Couldn't you find any furry knobs?!

Can I suggest knobs made from troll heads,
http://1.bp.blogspot.com/-lrU5clQF0JU/T3l09onbW7I/AAAAAAAAAsQ/AhvJmhB8xdE/s1600/SDC12051.JPG

[bluebunny]

That's what I got so far:

Lol! This is getting out of hand already. Couldn't you find any furry knobs?!

Looks like it was left in the bottom of the fridge for a few weeks!   

[Zwachi]

^I would like to know more about your Cliff branded 3PDT.  Is that an actual UK-made item, or a Taiwanese part?

I'm sorry but I've no idea. I purchased them years ago on ebay from a private seller..

Lol! This is getting out of hand already. Couldn't you find any furry knobs?!

It started with faux fur and then I wanted something even more eye catching for the stage.

Those are the others meanwhile:

[bluebunny]

That's quite a menagerie you have there.   

And I think we may need a picture of that Gretsch in another thread.   

[duck_arse]

That's what I got so far:

finally, TOY FUR! we should talk .....

[Zwachi]

After several hours of thinking about wahs and the Tremshifter, I decided to leave the pedal as it was intended and work on something new.
I just can't see an elegant way to make both rate controls controlable via expression pedal without having +5V on the external pedal. In this case I would rather put 2 vactrols across the rate pots and sweep their voltages with the expression pedal.

Instead I took the idea of Craig Anderton's Anti Wah and the Parasit Studio Sentient Machine in combination with vactrols and reduced the LFO part to only one STOMPLFO.
This circuit should be easily fit on Freppo's PCB. The switches give many options for lowpass, bandpass and highpass filters and only applying one LFO gives me more space in the enclosure for onboard Offset control.

Should work as well, doesn't it?

[ElectricDruid]

I just can't see an elegant way to make both rate controls controlable via expression pedal without having +5V on the external pedal.

What's wrong with having 5V on the external pedal? I was thinking of using a stereo/TRS socket to switch between the pot and an external expression pedal and I was worried about potentially shorting the 5V supply to ground when someone stuck a jack into the socket, but it was pointed out to me that even a small resistor hanging off 5V reduces the current to a safe level. I used 220R. This thread:

https://www.diystompboxes.com/smfforum/index.php?topic=119963

Don't make it more complicated than it needs to be.

[Mr. Lime]

Sorry if it's offtopic but the subject writes MULTIFLANGE;

Is the MULTIFLANGE compatible with an Ibanez flanger FL-99? Clock is MN3102 and MN3210 serves as double BBD. There are pins to connect to VGG. 

Schematic: https://www.dirk-hendrik.com/temp/ibanez_fl99.pdf

I very much appreciate help! 

[Fender3D]

If you lower VBBD to 5V... yes
Vgg is just a tension, it should be 14/15VBBD (on posted schematic).
You can get it with a couple of resistors (Ohm rulez..).
Then you can use MULTIFLANGE chip with fl99.
You must lower VBBD to 5V first, though...

BTW compatible DOES NOT mean pin-to-pin compatible

[Mr. Lime]

Thanks Sir!

Ahhh, I see.
Regulated 5V + interstage divider (470R /3k9) for VGG ~4.6V  and that's it? 

[Fender3D]

Yep,
I would use higher value resistors (I'm accustomed to 7K5 and 100K) so you won't load the regulator too much, but it will work the same.

[Zwachi]

I just can't see an elegant way to make both rate controls controlable via expression pedal without having +5V on the external pedal.

What's wrong with having 5V on the external pedal? I was thinking of using a stereo/TRS socket to switch between the pot and an external expression pedal and I was worried about potentially shorting the 5V supply to ground when someone stuck a jack into the socket, but it was pointed out to me that even a small resistor hanging off 5V reduces the current to a safe level. I used 220R. This thread:

https://www.diystompboxes.com/smfforum/index.php?topic=119963

Don't make it more complicated than it needs to be.

Yeah switched jacks are what I had in mind too but there is little place for other switches and controls. Controlling both LFO rates with expression pedal would lead to a synchronization which is the same sweep as with only one LFO. I had to ditch the Offset controls which could be pretty useful as well. Same with the Tap tempo switch which would be also synchronized by tapping both. There are little economic aspects for upgrading in this particular situation, especially if my target was to have none synchronized LFO sweeps controlled by expression pedal and the rate knobs. Beside that, the PCB is almost put together and it's handy to simply use an passive EXP pedal.

But I really like the idea of the STOMPLFO, I already ordered some and that's why I'd like to make another circuit with an extended filter for better wah wahs and a bigger enclosure for more controls. We might can think of throwing two LFOs in the new circuit. Probably a cool idea to have two independent LFOs for the LPFs sweeping against each other but can easily be synchronized by tap tempo or expression pedal? The PCB for the State Variable Filters is ordered as well.

[Zwachi]

The LFOs already arrived and here's what I'd like to do:



I simplified the tremolo circuit along the lines of the Demeter Tremulator and added a "Sync" switch to toggle between both LFOs for Filter B. I'm not quite sure what's to expect from those countless setting possibilities but hope to get some ringmod kind of tones with two independent LFOs sweeping different Filters in sample and hold mode..
But hey, at least there should be some useful "wah" and "vowel" sounds. 

What do you guys think?
Anything you would change?