Death by Audio Robot Schematic.

[Devius]

Anyone come across the  schematic for this killer effect? Oh, and how do I post pics on here?

[LucifersTrip]

Anyone come across the  schematic for this killer effect?

Oh, and how do I post pics on here?

hit quote and look at this post

[~arph]

That is completely missing the never really cleared up wiring of the rotary switch.
Head over to the 'other forum' to find a full thread on this pedal.

[Mark Hammer]

A buddy is bringing one in for modding sometime in the next week (he finds it too harsh-sounding).  I'll report back any useful information I glean.

As an aside, this is NOT a pitch shifter.  It is a frequency shifter.  A pitch shift nudges all frequency content in a given direction by the same proportion, with all relationships between fundamental and harmonics preserved.  A frequency shifter simply adds a constant to everything.  So, let's say the input signal is 400hz and has harmonic components at 800hz, 1600hz, 3200hz, etc.  If we were to pitch-shift it upwards by 200hz, we'd now have a fundamental at 600hz and harmonics at 1200, 2400, and 4800hz.  If we were to frequency-shift it by the same amount (200hz), we would now have content at 600, 1000, 1800, and 3400hz.  You can see that the mathematical relationship between the harmonics is "disturbed".  That's part of what gives it the ring-modulator-like sound.

Former forum member Mike Irwin designed a pretty nifty frequency-shifter module for modular synth company Modcan, which you can hear demoed: http://www.modcan.com/bseries/freqshift.html

[~arph]

Nice, I'm especially interested how pins 1, 2 and 3 are wired to the rotary and how the pins 15-18 are connected (if at all).
Prepare yourself for a confusing and horrible layout 

[WhenBoredomPeaks]

I have a couple of those ICs (HT8950) but i have never managed to make them work, is there a definitive working circuit out there? (i have found the one in the datasheet confusing)

[~arph]

same here, I breadboarded it and could only get one or or two of the sounds from it and only by using the pins 15-18. (which need momentary inputs)
EDIT: Perhaps a bad batch? mine came from futurlec.

[Devius]

I'm noticing alot of these crazy sounding effects all use an input buffer/effect/output buffer layout but then again I'm sure its more common in most aspects of effects pedalry.
Thanks for all the posts! A definative schematic would be the cats pajamas!

[WhenBoredomPeaks]

same here, I breadboarded it and could only get one or or two of the sounds from it and only by using the pins 15-18. (which need momentary inputs)
EDIT: Perhaps a bad batch? mine came from futurlec.

Mine came from ebay from some random chinese seller, they can be fakes maybe

[Mark Hammer]

As promised, my buddy brought it over and I snapped some pics.  Unfortunately, as a double-sided board, some of the traces are going to be under the rotary switch, which may make it hard for folks to decode how the unit is using the chip in the various modes.  That said, there is a reasonable amount of information contained in the photos.  I hope they are useful to people, and lead to some interesting mods.  My apologies for not taking higher-res pics.  Didn't realize until just now that I had the webcam set for such a low resolution.   You can see that the 1M pot is a trimpot, and that there are spaces on the board for components that were either unnecessary, or that they had second thoughts about.

For my part, my friend found the tone too dull for his tastes, so we took the 470pf feedback cap out of the output stage, and went with 270pf instead.  That ended up striking a sensible balance between being able to cut through in a band context, without inviting too much artifact nonsense.

Boy, this is one silly pedal!  Interesting effect, but probably needs a momentary stompswitch, since I can't see anyone wanting to use it for more than a bar at a time.  It is also VERY low-res as digital pitch-changing devices go.  Like I told my friend, the chip was conceived for kids toys and gag devices, not for pro musical applications.  It does what it does, and DBA took the ball and ran with it.  Good on them for fanny-pack from a sow's ear.

http://img.photobucket.com/albums/v474/mhammer/robot5.jpg
http://img.photobucket.com/albums/v474/mhammer/robot4.jpg
http://img.photobucket.com/albums/v474/mhammer/robot3.jpg
http://img.photobucket.com/albums/v474/mhammer/robot2.jpg
http://img.photobucket.com/albums/v474/mhammer/robot1.jpg

[Devius]

I breadboarded this and got er fully functional. According to the revolution deux site, all the rotary does is connect pins 1,2,3 to ground. Pin 15 is vibrato, sounds forking killer when you turn the control knob down.  As stated previously, momentary switches on pins 16, 17 change frequency up or down. I'm getting way too much low end through what I've built so I suppose I'll mess with the caps until I'm happy.

I can't wait to get her cased up,modded, monicker'd, and ready to rock!

[Hallmar]

Is it just me or are those solder points not that well done?

Look at the solder for the pots and footswitch and some other soldering points.

Funny. Maybe they've gotten better at it.

[czymaupy]

Look at the sample circuit in HT8950's datasheet.

https://www.sparkfun.com/datasheets/Components/General/8950v110.pdf

[goldenmonkeycolor]

As promised, my buddy brought it over and I snapped some pics.  Unfortunately, as a double-sided board, some of the traces are going to be under the rotary switch, which may make it hard for folks to decode how the unit is using the chip in the various modes.  That said, there is a reasonable amount of information contained in the photos.  I hope they are useful to people, and lead to some interesting mods.  My apologies for not taking higher-res pics.  Didn't realize until just now that I had the webcam set for such a low resolution.   You can see that the 1M pot is a trimpot, and that there are spaces on the board for components that were either unnecessary, or that they had second thoughts about.

For my part, my friend found the tone too dull for his tastes, so we took the 470pf feedback cap out of the output stage, and went with 270pf instead.  That ended up striking a sensible balance between being able to cut through in a band context, without inviting too much artifact nonsense.

Boy, this is one silly pedal!  Interesting effect, but probably needs a momentary stompswitch, since I can't see anyone wanting to use it for more than a bar at a time.  It is also VERY low-res as digital pitch-changing devices go.  Like I told my friend, the chip was conceived for kids toys and gag devices, not for pro musical applications.  It does what it does, and DBA took the ball and ran with it.  Good on them for fanny-pack from a sow's ear.

http://img.photobucket.com/albums/v474/mhammer/robot5.jpg
http://img.photobucket.com/albums/v474/mhammer/robot4.jpg
http://img.photobucket.com/albums/v474/mhammer/robot3.jpg
http://img.photobucket.com/albums/v474/mhammer/robot2.jpg
http://img.photobucket.com/albums/v474/mhammer/robot1.jpg

Hey man, I built this pedal from this schematic and the layout at this link  http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/DBA/01-DBA_ROBOT_VERO.png][url]http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/DBA/01-DBA_ROBOT_VERO.png[/url]  and i'm having very strange issues with volume control as well as the gain pot is backwards... I think i could fix the gain pot, but not sure about the volume, nothing ive tried works.

There is a huge jump in volume at about the halfway point on the pot.  At first it would get decently loud, just under unity (up to the jumping point) then it would get a huge boost from that point on.  Now its changed... now it is very quiet up to the jump- it has a lot of volume at the point where it jumps then it goes back down to very low volume after that point.  I've tried new pots, new wirings, all the comboes i can imagine (maybe I skipped one- if i could get the correct volume and gain pot wiring that would help eliminate other possible factors.  Could it be the ht8950 or my opamp?  I've been over and over the schematic and vero, measured all the resistors (dont have anything to measure caps in circuit though)

any help would be much appreciated!!!