My digital distortion

[Squeal]

This is an ADC0804  A/D Converter chip with a jrc4558 for pre and post gain. Pictures:


http://i35.photobucket.com/albums/d190/squealmoanhowl/DSCN0187.jpg
http://i35.photobucket.com/albums/d190/squealmoanhowl/DSCN0188.jpg

Sounds:(play the hifi link if you can)

http://www.soundclick.com/bands/pagemusic.cfm?bandID=463018

[Squeal]

Oops....forgot I had two songs up. It's the "digimonkeys raging" song.

[Dave_B]

What are you doing after the ADC?  Are you converting it back to analog and leaving some bits unconnected or are you just mixing the the bits back together at the op-amp.  Cool sound.   

[Squeal]

There's no dac, the bits are mixed through resistors into the opamp. The dip switch engages individual bits.(there are

[Alex C]

Is that an Electro Harmonix box?  It sounds great, and thanks for the "guts" shot, I love those.
-Alex

[Squeal]

Box is a bassballs

[chokeyou]

SCHEM!!!!

its really cool, im really interested to see how you did that.

[DavidS]

Yep, we need a schematic!

[Paul Perry (Frostwave)]

For even more mayhem (not that it is needed!) you can put a LFO on the reference input to the ADC0804 (watch for voltage level limits, though).

[Ge_Whiz]

The KNOBS! Tell us about the KNOBS! 

[Squeal]

Ok knobs from left to right: Gain, Sample rate, Feedback amount, Volume.

The dip on the left engages bit feedback to the adc input through the Feedback amount pot (100k).The dip on the right engages bits to the output amp. The sweeping sounds on the recording are with the Sample rate knob. The two switches to the right of the dip's are both for the feedback also. One is momentary, for hitting with my foot.

I don't know how stable my design is, so I didn't want to put up a schematic. It takes time to "warm up", and sometimes I have to unplug and plug the battery to get it to go. that said, maybe I will post something in a bit. Someone here could probably refine the pre-gain section alot better than me.

There is no feedback engaged on the recording. It's just ridiculous for guitar. For drumbeats it may be useful.

[Squeal]

By the way, special thanks to RG and others who gave me tips on opamps a few months back. That info helped get this pedal running as well as a ring mod I was doing. Thanks.

I would suggest to anyone with any experience to build the circuit straight from the datasheet in "free running" mode. (it's on the sheet, link below) Put a pot in place of the resistor on the clock input. Mine is 100k.

http://www.national.com/ds/DC/ADC0801.pdf

You will probably need a boost in front of the input. If your adc is powered with 5v and ground is at 0v, then your signal should be biased to 2.5v. Equivalently, if you think of your signal's ground as 0v, then power the chip with +/- 2.5v.

[Dave_B]

Is in possible that the lockups you're experiencing are caused by the signal getting too hot and exceeding the ADC's max input voltage? 

[troubledtom]

By the way, special thanks to RG and others who gave me tips on opamps a few months back. That info helped get this pedal running as well as a ring mod I was doing. Thanks.

I would suggest to anyone with any experience to build the circuit straight from the datasheet in "free running" mode. (it's on the sheet, link below) Put a pot in place of the resistor on the clock input. Mine is 100k.

http://www.national.com/ds/DC/ADC0801.pdf

You will probably need a boost in front of the input. If your adc is powered with 5v and ground is at 0v, then your signal should be biased to 2.5v. Equivalently, if you think of your signal's ground as 0v, then power the chip with +/- 2.5v.

what page on the pdf,
         thanx
               - tom

[Squeal]

tom- The first schematic it shows is good but then you have to do different things with the cs and reset pins, I think. A few pages down it will show "free running" schematics, but it only shows the pertinent pins. So set it up like the first schem but with the changes found in the free running section. Does that make sense?

bellyflop- I don't know. The thing works fine once it's going. I think it has to do with the interrupt pin. I suspect that giving the input too much voltage will only cause it to chop off the peaks, hard clipping style. Which is probably what mine is doing all the time. It doesn't clean up. When I turn the pre-gain down, it gates out heavily. Well, it always gates, but it's not such a problem with the gain pumped, ya know?

[troubledtom]

cool , thanx bro!
     peace,
        - tom