Ringdroid - a sample and hold ring modulator

[thelonious]

Add me, too, please! Thanks for all the work you've put into this.

[tyronethebig]

And me plz!

[Ry]

Please add me to the list as well. 

Thanks!

[John Lyons]

John, did your PCB work out okay without any changes?  The demo sounds very nice.

Mine works as stock but I would add some changes to alter the ring volume as well as lowering the
frequency, perhaps a frequency range switch. I need to get back to it and iron out the wrinkles.

[Laky]

I just breadboarded this and find that when the gate knob is set such that the gate is always active (just at the point the LED turns from red to blinking green), there is a constant high-pitched whine that irritates the Dog and The Wife.

Is that a feature or did I make a mistake somewhere? I have little experience with how a ringmod should behave, with the bulk of my builds being in the more straightforward distortion/fuzz area.

The whine responds to the setting of frequency knob, so at least I know that the FREQ knob works. And the whine speeds up as I turn up the TEMPO so I guess that works too.

Cheers for any guidance you might be able to give.

BTW, I incorporated the mods Earthtone (I think) suggested and they were useful. My IC chips (apart from LM324 and TL062) have BE after them. Not sure if that makes a difference. Else everything is stock as per the schematic.

[~arph]

As PM'ed.

Yes that whine is normal. That is where the gate is for, to shut that when you are not playing.

[~arph]

Here is a little update

I'm working on a revised version. On with depth and volume controls.

I tried the ringdroid with humbuckers and noticed a difference. Less obvious carrier and more depth.
It makes perfect sense. So here is something you can do to make your ringdroid a bit quiter and have some way to control depth of effect.

1. Run a booster in front of it with a gain of about 2.5 (depends on your guitar). To much gain will cause clipping.
2. Add a volume pot at the end. This way the carrier noise will be 2.5 times less in volume. (as the carrier amplitude remains the same in the pedal)
3. Optional, replace the 68k resistor with a 100kB pot with a 10k in series. This gives you some control on the depth.

The revised version will have these mods (plus pre and de emphasis.)

The downside is that I'll have to redo the PCB and it's going to be bigger. 

[Zwachi]

Any chance to have a look on the schematic again? Links are all dead.. 

[BetterOffShred]

Yeah man I'd love to see it too love me a good ring mod

[~arph]

Here you go,

https://www.dropbox.com/s/ry9e93ypuo3tmzb/ringdroid_v201301.pdf?dl=1

[Zwachi]

Thanks a lot! 

[BetterOffShred]

A Google search yielded this schematic but with all the tl074 references crossed out and LM324 specified instead.  I assume that's still true ?   

[~arph]

Yeah, it is stated in the PDF too. I needs rail-to-rail.
I'd do this whole thing different now btw, I had a better sounding version with a ATTiny85 and an XR2206. I did envelope and random. Can't find any samples sadly, but it looked great:

https://www.dropbox.com/s/wtlgjr0hqsiczpz/rebel_1.jpg?dl=0

[BetterOffShred]

Hey that's cool man.  Any build info on that one? I have some 2206s leftover from other builds 

[~arph]

If you take this:

https://www.dropbox.com/s/8o0nldwmkbu2ij4/superfast.png?dl=0

And feed(source) pin 7 with a random voltage (max 3v I believe) you get the same thing. Only then with a perfect sine wave modulator signal instead of a square wave, much nicer ring modulation sound.

I was using the uC (it was an ATTiny84 btw) to modulate pin 7. And I was feeding the uC with the guitar input and some switching logic.
It did envelope up/down, manual, and random.

[BetterOffShred]

Well I know what my next breadboard project is!   Thanks for sharing this.