CMOS GRACE

[WGTP]

http://aronnelson.com/gallery/main.php/v/WGTP/CmosGrace.GIF.html?g2_imageViewsIndex=1

I'm thankful for the many wonderful harmonic generating devices made possible by this place. 

[bluesdevil]

Well if you're thanking Leslie West in your build notes, I probably need to throw it on the ol' breadboard pretty soon!! Same chip as the Red Llama?

[WGTP]

Leslie is the MAN for Mountainous Tone.

Currently a 74HCU04 is on the bread board with it, but I have been using the 4049 as well.  Either should rock, but the 4049 is a little woolier and the 74 is a little brighter and tighter, IMHO. 

[bluesdevil]

Help!! Got it on the breadboard and it would sound killer if I didn't have this loud, howling oscillation. I installed a 330uf cap across the rails and ran a 470R resistor from the + supply to circuit as well. I made sure to ground pin 8 and pins 9 and 10 of the unused inverter. Does it matter which inverters I use or what order?
    I doubt this would matter, but I subbed the 470pf with a 560pf in the 3rd stage. Battery voltage is 9.30volts.
               

[blanik]

this looks highly interesting!

if i get your schem right it's an overdrive unless you connect the two diodes and the swt to 100n--Ground... is there a drive pot? (making the second or third 100k FL would make it a drive knob?)

[WGTP]

Try reducing the 100k resistor in the last stage to 10k.  If that doesn't reduce the Low frequency rumble, do the same to the next to the last stage.  You may then need to reduce the Caps in the FML accordingly.   

A 1 Meg pot at the input is probably the best Gain/Drive pot.   

It's milder without the 100n connected to ground.  The diodes are for a different effect, should add some compression.   

Thanks for trying it. 

[bluesdevil]

Thanks for the tips, but still no luck. When I lifted the .1uf to ground the lower rumble turned into a higher pitch... maybe a clue. I'm using a HCF4049UBEY chip if that makes a difference. I'll try reducing some of the  caps before calling it quits.

[snap]

Help!! Got it on the breadboard and it would sound killer if I didn't have this loud, howling oscillation. I installed a 330uf cap across the rails and ran a 470R resistor from the + supply to circuit as well. I made sure to ground pin 8 and pins 9 and 10 of the unused inverter. Does it matter which inverters I use or what order?
    I doubt this would matter, but I subbed the 470pf with a 560pf in the 3rd stage. Battery voltage is 9.30volts.
               

DON`t ground pin 10!

[WGTP]

I don't understand this, but try removing the caps in the feedback loop, or try different values.  They seem to have a weird effect.  Also I have the input of the unused stages to +9v  Leave out a stage and see if that helps.  It is pretty high gain as shown.  Good luck.   

[bluesdevil]

Thanks, I'll keep trying!!! I'll let ya know if I have success.

[snap]

when the fourth inverter is unused, its input should also be grounded.
Any highgain circuit is sensitive to lead dress issues and inphase outputs being physically close to inputs!

[WGTP]

There are many variations possible.  If this one doesn't work, try something with fewer stages and/or smaller resistors in the feedback loop(FBL).  Start with the first stage and make sure it's working and then keep adding stages.  The strange one without a resistor in the feedback look might be causing problems.  Try leaving it out and using 10k resistors in the FML.  Should get at least 4 stages working that way.  Also might try 1-10k resistors between stages.  Sorry for the trouble.   

[bluesdevil]

Sorry, I had to finally give up. I tried everything including reducing the FBL resistors, less gain stages, proper shunting of unused inverter inputs and different caps, but it really wimp-o-fied it and still had a weird oscillation going. It sounded so damned massive originally, I might just have to make a pcb (with sockets) for it and see if that helps. Now I know why the Red Llama only uses 2 inverters!!!!!! I really love the CMOS distortion stuff, but my breadboarding skills may be a bit too sloppy for it.

[WGTP]

CMOS's have put me thru some ****.  It seems more inconsistant than regular op amps.  Sometimes weird things start happening, and then mysteriously stop.  Sorry it didn't work out.