Anybody build their Gristleizer yet, comments on it?

[glops]

I got a dumb question.  According to this picture on page 1, if you look at the bottom left of the board at the SPEED 10K A holes, from left to right, what would be the corresponding 3-2-1 for the pot connections?  Does that make sense? This is first time with a PCB, so don't know what the standard is. I've had this PCB for over 3 months now and it's almost completed.  I would like to not have to resolder the 3 and the 1, ya know.

Thanks,
Richard

[Taylor]

Looking at the front of the board, with the component legend readable correctly, the counter clockwise lug of each pot is on the left. Not a dumb question at all, and in the future this info will be on the board.

[glops]

Looking at the front of the board, with the component legend readable correctly, the counter clockwise lug of each pot is on the left. Not a dumb question at all, and in the future this info will be on the board.

That's what I thought, just wanted to make sure.  Can't wait to fire it up, have never used a rotary and that will cause some stress but hopefully tomorrow I'll test it out....

[glops]

Finally finished it up!  The reverse etching didn't come out as clean as I originally intended but I think it came out better this way.  No paint, just some scrubbing with a brush and a clear coat.  It sounds great Taylor!  Thanks so much for making this board. I posted more pics on the pics thread...

[jacobyjd]

Yeah. That's awesome.

[Taylor]

  Love it.

[1878]

Ooh... I like that.

[glops]

Pictures got lost in cyberspace.  Here again.  What a cool circuit!

Thanks Thanks Thanks!!!

[digi2t]

Wow, absolutely superb. Love the hash marks around the knobs as well. BRAVO!!

Cheers,
Dino

[Strategy]

Did anyone implement the expression pedal input for LFO Rate/Speed knob?

A broken pot (long story) gave me opportunity to go under the hood and try this according to Taylor's switching-jack diagram as per page 6. I'm not getting any results though. I tried with the Moog expression pedal as specified, also with a Boss one, no dice with either.

Fortunately I still get normal rate knob behavior when the jack has nothing inserted in it. But I'm hoping to still implement this while I've got this "up on cinderblocks in the front yard" so to speak.

If anyone can help and/or verify that wiring diagram or alternate rate expression configurations that would be great!

thanks
STRATEGY

[Taylor]

I can't think why my diagram wouldn't work - it's just subbing the pot in the expression pedal for the panel pot.

If you mixed up the sides - wired the PCB pads to the switched side - then it wouldn't work. I guess it could be ambiguous what "switches" meant here, so verify that the side connected to the pcb is connecting to the plug when inserted. In this jack:

Http://www.smallbearelec.com/Detail.bok?no=771

The "switches are on the left side in that picture. In this one it's the other way around:

Http://www.smallbearelec.com/catalog/Nmj6hcd2.jpg

Notice the way the pins on the non-switch side come up and bend over the top to contact the plug.

[Strategy]

Yep, the pot is attached to the switch side so that when you insert a cable into the jack, it disconnects the pot from the pcb and substitutes the pedal. Maybe I have the pcb-side wires going to the wrong pins of the jack. I'll check again

Strategy

I can't think why my diagram wouldn't work - it's just subbing the pot in the expression pedal for the panel pot.

If you mixed up the sides - wired the PCB pads to the switched side - then it wouldn't work. I guess it could be ambiguous what "switches" meant here, so verify that the side connected to the pcb is connecting to the plug when inserted. In this jack:

Http://www.smallbearelec.com/Detail.bok?no=771

The "switches are on the left side in that picture. In this one it's the other way around:

Http://www.smallbearelec.com/catalog/Nmj6hcd2.jpg

Notice the way the pins on the non-switch side come up and bend over the top to contact the plug.

[digi2t]

I used this diagram, http://picasaweb.google.com/lh/photo/agO0OKTabUMuBF9PjMwzfg?feat=directlink, and have 2 expression pedal jacks. One for depth, and one for speed. Just make sure you insulate the jacks from the casing though. I used the shoulder washers from Switchcraft. The jacks are stereo switching jacks, with a N.O./N.C. contact on the tip and ring. Got them from here; http://www.guitarelectronics.com/product/JK31/9-Pin-14-Stereo-Jack-w-DPDT-Switch.html .You can see them, upper left of the enclosure (next to the stomp switch). I use a 100K volume pedal as the expression pedal.

[Strategy]

Thanks for posting that.

So, I think that one issue for me is this: I used a 100K moogerfooger expression pedal and it would appear to not work for LFO speed because that is a 10K Audio taper pot. By that, the 100K should reach maximum resistance very quickly.

I tried my 10K boss expression pedal and that did not work either, though, so mystery still unsolved.

I'll try the expression connections in your diagram you posted in the link

thanks
STRATEGY

[thedrivel]

The only JFET Small Bear has is the 2N5461. Will that be ok in place of the 2n3819?

http://www.smallbearelec.com/Detail.bok?no=1071

Also, how to I determine the correct resistor for the flashing LED? I was planning on getting this one in green:

http://www.smallbearelec.com/Detail.bok?no=333

[Taylor]

According to the original designer of the circuit, Roy Gwinn, any JFET should work. Since the bias can be trimmed, differences in individual JFETs can be accounted for. Note that they may not have the same pinout, and make sure you've got the pins going to the right points - the gate, drain, and source are marked by "G D S" respectively on the PCB.

[thedrivel]

According to the original designer of the circuit, Roy Gwinn, any JFET should work. Since the bias can be trimmed, differences in individual JFETs can be accounted for. Note that they may not have the same pinout, and make sure you've got the pins going to the right points - the gate, drain, and source are marked by "G D S" respectively on the PCB.

Thanks Taylor. I see that Mouser has a few 2n3819s. I'll just buy what the BOM calls for. I don't know enough to improvise, but I can follow directions okay. Earlier in the thread you mentioned you were creating a mouser part# list I think. Did you finish it? Excited to get cracking on this after building your Tap Tempo Tremolo.

[Taylor]

Generally for all the projects, for parts that need to be one specific part, I include a part number. For most things, people use all different kinds of caps and resistors, etc. so it wouldn't make too much sense to include part numbers for some arbitrary brand and tolerance value.

[boblob]

I've built a couple of these now on vero with a revised layout using two TL072s (one for the input and output buffers, one for the oscillator) and a single TL061 (for the waveform-shaping bit).  The 741s don't really bring anything special to the party - the lower current more modern ICs sound very much the same to my ears. I did have to sub a couple of resistor values in the oscillator to give it a good usable range and upped input impedance has also been upped to ~ 1M, otherwise it's the same as the 741 version.

Ticking problems are greatly mitigated by using good quality shielded cable for the input and outputs, and also, importantly, on the VCA/VCA switch. What helps most though is to increase the value of the 100uF decoupling caps - on the breadboard going up to 220uF greatly reduced ticking with 470uF completely eliminating it; I had to go up to 1000uF on the final vero and siting them as close as possible to the power pins of the oscillator IC also helps.

Taking down the corner frequencies on the pair of low-pass filters also got good results - I went with a 100k + 200nF and 150K + 100nF combination (Taylor's 10uF de-tick cap did nothing for my build). Limiting current to the oscillator IC didn't do much either except make the LFO pulse too weak to get distinctive waveforms. I also tried subbing the oscillator for the less brutally square one from the Stompbox Cookbook, but again it couldn't produce the nicely defined waveforms that you get with the stock LFO.

Phew. I have learned tons of useful stuff from this build - if you've already tackled a simple tremolo or the like, then this is a really good build to take you up to the next level.

[fleeps]

Pictures got lost in cyberspace.  Here again.  What a cool circuit!

Thanks Thanks Thanks!!!

Love it!
I guess you solder the pots directly onto the pcb? I'd imagine the knobs would be closer together....