Monday, 14 April 2014

Grind Customs Electric Boogaloo Optical Tremolo

Another project collaboration between Rej at Grind Customs and CultureJam, similar to the Shoot the Moon but with a couple of subtle differences including a shape switch instead of the wave pot (similar to the 2 knob version we did).  If you don't want to roll your own with the LDR and LED, the Vactec VTL5C3 is the recommended vactrol.

I can't find a video anywhere, so if anyone can make one that I can post with the layout that would be great.


  1. Built it. I'm a fool for Tremolos.

    It's a decent sounding tremolo but I'm going to play around with some components and see what I can manage.

    - I used a Tayda photoresistor which I believe has a wider swing than what is recommended for this, so take that into account.
    - I used a 3mm Red waterclear LED for D1.
    - This things is FRIGGIN LOUD. I had to put the gain trimmer on about 1 or 2 for unity.

    - Depth control seems useless up until about the last 20%. I don't hear any "tremoloing" in the first 80%. Max depth is fairly moderate. I wonder if a different photocell closer to the specs listed here would shift this where it needs to be. I'll definitely be trying a different value. Ordering some now.
    - The speed control seems off. I think that a C100k antilog pot would better fit. The speed increase is very gradual until the last bit of the rotation where it increases very very quickly. I don't have a C100k pot handy at the moment and I'm not sure if a different photocell would affect this. I've got both on order and plan on testing these changes out.

    Regardless of the above, it works :)

  2. what about his voice? Can like tremolo in magnus modulus? thank before

  3. I realized I actually have a VTL5C3 (though I still want to roll, my own*) so I put it int here and it seems to have fixed some of the issues I heard before.

    Here's a really shitty recording (woke up this morning with a painful stiff neck and just didn't feel like re-recording... sorry about the microphone bumps). It should at least give you an idea of how this sounds:

    Mahogany body guitar, rosewood fretboard, P-90 bridge pickup, and a little reverb on my amp because I was too lazy to go turn it off.

    For the record, I still think this would benefit from a C100k reverse log Speed pot instead of a linear one.

    One other problem is the LFO LED. I've gone over and over it and it's not working for me. I took the LFO- to the LED Anode and took the LED Cathode straight to Ground and it works. *shrug*

    * I keep a small handful of Vactrols on hand, but since the damn things cost so much, I use them to make sure a circuit works, and then I roll my own, based on the specs of the Vactrol. That way I know for sure if I horked the circuit or badly rolled my opto-doobie. It's also cheaper :D

  4. GL5516 photocells should work perfectly in this (5-10k/500k). I'll be testing it out as soon as mine arrive. They're easy to get on Ebay and CHEAP from China. I paid a bit more for a handful from a domestic seller so I can get them quicker and report back.

  5. woowv: D nice sound man. are you sure the LFO led not work? This cool man, damn fuck yeah i like this tremolo, I just had a pot B1K and B100k man, does this work?

  6. Those pots should work fine. It's just increasingly sensitive the higher you turn the speed up. I think it would be "smoother" with a reverse audio log pot, but I currently have it built with B1K and B100k and it's perfectly usable.

    The LFO led could be something I messed up, but I'll be damned if I can figure out what. If you build this and have the same issue, then just take the wire marked LFO- to the LED Anode and take the LED Cathode straight to Ground and it works for me.

  7. Sorry somehow I absolutely missed this, thanks for verifying buddy :o)

  8. Lo, there do I see my transistor.
    Lo, there do I see my socket.
    And my IC and my diode
    Lo, there do I see the trace of my circuit
    Back to the ground.
    Lo, they do call to me.
    They bid me take my place among them
    In the halls of Pedal-Valhalla
    Where the Verifier may solder forever.

    1. And there endeth the sermon according to Heath!

  9. Just a little more info here:

    - 100k Rev Log pot for Speed, DEFINITELY recommended. Tested, works better.

    - Out of everything I tested, the VTL3C5 still sounds the best. The only other combination I tried that didn't sound like pants was an NSL-7530 paired with a diffused Red LED. It caused a significant increase in Gain but otherwise sounds *almost* as good as the VTL3C5. I'm mostly judging this on providing a useful "Depth" since only the vactrol and NSL rolled thingy gave a usable amount of Depth and the rest didn't. Even with the vactrol, the first half of the Depth control isn't very useful. Still, all the way up gives a nice moderate tremolo.

    - Related to the above LDR info, 5k - 500k is not going to cut it at all. You will be VERY disappointed. What you need is about 30k - 10M (the NSL LDR I mentioned above is 10k - 6.7M (though reportedly they go as high as 10M.. my meter only goes to 2M :/ ) There are other factors involved (ie. the NSL gain jump... the trimmer helps with that) but that should be a good reference point.

    If the components controlling the Depth could be isolated (and I'm speaking somewhat from ignorance, so forgive) and socketed then it would be cool to be able to tune this to the LDR, which would be way less expensive than a Vactrol. :D

    Until someone figures that out (and I'm not going to hold my breath.. there are a lot of GREAT tremolo layouts here) I gotta say, if you are going to build this, get the VTL3C5. Otherwise just build a Heartbeat Tremolo (one of my very first builds here and still a favorite).

    Peath out.

  10. put tl072 in place tl062 ,?i just have two tl072