Anybody build their Gristleizer yet, comments on it?

[Taylor]

BetterOffShred's suggestions sound good to me, but regarding your number 2, the "de-tick" cap on the board is connected to the LFO signal going to the FET transistor so that's different from power supply bypass caps.

I think it would be a good idea to put 100n caps from both the positive and negative power pins of the TL072 and TL074, going to ground. You want these caps to be as close as possible physically to the power pins, and with the leads trimmed as short as possible.

[BetterOffShred]

I tried a 470uf on 4 and 11, no dice.  I'm pretty happy with this the way it is, but I'll try the 100n's. I think the circuit is what it is, and I really enjoy it's overall sound. I've seen some layouts with everything split Into single opamp but reports are that they still tick here and there.

Get those wires as short as possible and shield the in and outs to/from everything, making sure to ground only one end of the shielded cable.

[lulu_joe13]

Taylor, perhaps this is a question beyond good support but if you have time can you answer or send me where there is some instruction. I just got an oscilloscope and want to use it to tune my Gristleizer. Where do I attach the test lead on the PCB to adjust the shape or is it on the leg of trim trim pot and ground? What about for the offset? Thanks as always for any help. JoeF.

[Taylor]

For both, you can view the LFO waveform by probing at the center lug of the Depth pot.

[arpaxxe]

Hey all. This thread's been great to read through.


I've got everything installed but the only thing I'm getting out of it is a steady click. The click isn't affected by changing the speed, but it does go away if I back off the level all the way. I've confirmed the placement and connection of the ICs, caps, transistors, and diodes. Corrected a mistake on the ac jack. Reflowed a bunch of connections that looked shady. Still, nothing.

I'm wondering what steps I should take next. Does anyone have advice on how to continue debugging? This isn't my first build, but I am a bit rusty for sure.

Thanks!

Bryan

[BetterOffShred]

Make sure your 4 way rotary is wired correctly, are you certain of your FET's pinout?   I used 2N3819 in mine and it was a different pinout than the advertised for that chip, so I'd recommend testing it with something like a Mega328 if you have one.   What Diodes did you use?  I had a broken diode (glass germanium 1N34A) that gave me hella problems with mine, it looked fine but was cracked.

Also this pedal will make no noise if the bias knob is in certain positions, so tool around with that too.   I ended up putting a 47K resistor on one leg of a B10K and I think a 30K on the other leg, to get a more useful sweep since in all 4 settings the bias knob only has a little window (at 100K) where it did anything.     

[arpaxxe]

Thank you. I'll check this. Much appreciated.

Bryan

[Anspa]

Hello every one ! First post here and also beginner in electronics only 5 pedal builded, but it's just a begining (and also a poor english level, sorry for that, hope you'll understand me)
I've build a gristleizer but I'm experiencing some problems: Actually the lfo don't work, not a huge matter to identify that i've to buy a new TL074, but I prefer explain you the problem in case you'll think there is something other wrong. I've got sound bypassed and actived, when I'm on VCF the sound is aggresively filtred high, the level knob is working, that's seems to be nice.. but speed, bias, and depth don't do anything and the LED is on but not flashing (how ever when setting the speed knob at maximum the LED turn's off)
Is that just because of the TL074 that's certainly dead or is there anything else ?

Thanks for you're help, I spend a nice time reading the all thread ! And thank you Taylor for bringing the possibility to build this incredible box !

[BetterOffShred]

I believe the FET controls the LFO and it's kind of sensitive.   I used a 2N3819 in mine, though I believe lots of people got it working with a J113.. reports of J201's and 5457's working too, but mine only ran on the 3819.  My pinout was different than the board showed too, so make sure that's correct

[BluffChill]

Ooh Gristleizer thread!
I've built several Gristleizers, I know this weird old circuit pretty well. I even made a horrendous Vero layout for it here:

https://bluffchilldevices.blogspot.co.uk/2018/01/vero-layout-gristleizer.html

Video:

https://www.youtube.com/watch?v=flXiQz4Z98w

Can I embed here?

<iframe width="560" height="315" src="https://www.youtube.com/embed/flXiQz4Z98w" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>

[Anspa]

I believe the FET controls the LFO and it's kind of sensitive.   I used a 2N3819 in mine, though I believe lots of people got it working with a J113.. reports of J201's and 5457's working too, but mine only ran on the 3819.  My pinout was different than the board showed too, so make sure that's correct

Thanks for your answer !
I'm on a 2N3819 too, are they always on a different pinout or is it specific to some of them ? I'm not at home actually so can't try... I ever put it under tension, so if the pinout is different, did I kill my 2N3819 or will it works however ?

[BetterOffShred]

I honestly don't know, I used the mega328 tester from eBay to determine DSG on the device and then twisted the legs to match the PCB.  I'd highly suggest getting one for just such a occurrence. I can check the pinout on mine when I get home and I'll post an update with a pic.  I'm sure the FET is fine. 

[Anspa]

Hi ! I've tested different pinout for the 2N3819, but no result, it (don't) work the same....
Any ideas or suggestion would be welcomed
Thanks

[BetterOffShred]

I totally forgot to check mine!  I'm an ass! sorry.    Well could you post pics of your build?   If the LFO is not working that seems like the culprit but it's difficult to tell if maybe something else is jacked up without pics.    I had a broken Diode in my build (used 1n43A's.. went back to 4148's) and it took me a couple days to figure it out.   
As I posted in my build comments, I had better luck with an LM324 and a TL062, but that's just me personally, and if your LFO isn't operational it wont matter yet anyway.   

So no LED blinky yet?   Did you install that extra cap?   
It's curious that the LED doesn't flash, but goes out when speed pot is turned to max.. are you certain you have the correct size cap in the "Speed set" cap?  I believe it's a 470n in the schematic.. I think I upped mine to an 860n..   If you had a wicked small one in there it might affect the speed, but it sounds like you're not getting any depth at all..   

Pics!
-Brett

[Anspa]

No problème 
I've check my diodes, they seems to work well..
I've said a mistake, it's when speed is truned to min that the LED goes out ! I've didn't install the extra cap actually, should I ?
Here the pic, I hope you'll see something !

Thanks for your precious help !

[BetterOffShred]

Well the picture isn't too telling.  I would try fiddling with your wave shape and offset trimmers..   It's a hard device to dial in without a scope,  but I did mine by ear and I think it sounds good.   

So I just opened mine up and checked the Jfet, it's definitely a 3819, and my measured pinout is flipped from the pcb labeling.  That is, G is the middle but what I've measured as S goes in G on the board..  worth a try.  I measured another one I had to be sure ..

[BetterOffShred]

So it works with it either way  .. turn depth up to halfway, speed to halfway and then mess with the bias knob until you have sound.. then mess with the shape and offset trimmers. 

Mine also cuts the led off at all the way down speed.. well maybe it's just really slow.  I didn't wait to see. 

Sorry I haven't been much help

[Anspa]

Even if we don't find anything, thank for your help/time !
I'm not at home, so i need to check but I do remember that it was "G instead of S" too.
I'll try to fiddle with the trimmers this evening !
Led don't seems to turn off (in my case) because of a very slow speed cause when I'm turning down the pot very slowly, I can really see that the led is turning off progressively ...
Mistery..

Maybe my neighbour put a spell on me to avoid me to play harsh filtering all the night !