What’s on *YOUR* workbench?

jubal81 said:
I tore down the harmonic tremolo and built a two-stage Magnatone vibrato circuit with JFETs in place of the tubes and nsl32-sr3 vactrols as the voltage controlled resistors.

The linearization efforts give it a nice sweep without any "seasickness." I'm pretty surprised by the performance. I've been through more than a couple vibrato pedals and this is a pretty close second to the Origin Effects MAGMA. These vactrols are $4 a pop, though, and I'm really curious if I can get it working well with the 3 N-channel mosfets in a CD4007.

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I'm buttoning up a BJT version of the same thing. Used 9203 LDRs and made the caps in the phase stages switchable for different voicings. This is an update to my JFET version, which got too thumpy. I'd love to hear what the mosfets sound like!
 
Aleph Null said:
I'm buttoning up a BJT version of the same thing. Used 9203 LDRs and made the caps in the phase stages switchable for different voicings. This is an update to my JFET version, which got too thumpy. I'd love to hear what the mosfets sound like!
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Nice! When you say JFET, do you mean you were using them as voltage controlled resistors?
I've been looking at other LDR options. I'll have to check out the 9203s. I had my eye on the NSL-06s53 at Mouser, but haven't tried them yet - also rather pricey.

I. tried the cd4007 and an sd5000 array as VCRs, neither with much luck so far. I'm not going to bother with them because it just doesn't seem worth it considering the cost and performance of the SSI2164.
 
Yes: JFETs as voltage controlled resistors. The 9203 is 20k–5M. Looks like the NSL-06 is 50k–10M. I'm sure you could get similar performance by changing the capacitor values.
 
I have a several boards basically ready for pots and cases, so I ordered components to get them finished. Parts came yesterday afternoon, but the shipment was missing the cases. I got everything else ready to go. As soon as cases come holes will be drilled and paint sprayed shortly.

Here’s’ what’s on the bench:
Tommy III and Glory Hole - for my son. He uses mine and I want mine back!

Acetylene and Je T’aime
For me. A large board and about as small as they get.

2 Mantle Fuzz, with mods
I did the mod where Pin 1 to R20 are on a switch to go between the standard -2 octaves down and the -1 octave.

I also put the input cap C1 on a blender pot going between 3n3 and 47n instead of the stock 10n. I still may tweak this. Trying to make it more useful for bass. One is for me, and one is for a fuzz loving, bass playing friend.

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I watched some more demos of the MAGMA57 and I'm fairly certain it's a VCA chip without any linearization. The sweep is exactly what I heard when I was working with the THAT2162.

The DAC chip showed up today, so It's VCA experimentation time for the vibrato/harmonic tremolo. However, having the Maggie circuit on the breadboard and sounding so good got me juiced to extend it into a Univibe. So I worked it up with four JFET phase splitters in place of the BJT stages and added a mix control.

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Still tinkering with the Optos, wanting to really dial in that Univibe circuit and things are looking good.

I set up my oscilloscope with Channel 1 (yellow trace) tracking my LFO output and Channel 2 (blue trace) tracking a voltage divider with my modulation LDR (NSL32-SR3).
I dialed in the operating zone of the NSL32 so I get a really close approximation of a sine wave at full depth all the way up to 6Hz. Then I adjusted the capacitor values in the Magnatone circuit on the breadboard to compensate for the shift. Again, I've found LDRs to work much more consistently "mostly on," as these are set to vary only about 50K through the entire sweep.

Results are very promising and it's getting pretty close to the performance of a VCA IC.

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And here's a demo of the MAGMA for comparison:
 
bean said:
A little Chip Quik and you'll never have to do that. You can pull dpdt and 3pdt with ease.

Click to expand...

It's not cheap, but seems like a good investment. Curious if this SKU is "better" in terms of total material you get for the money? Watched a eevblog video on the one you posted and it's impressive.

Chip Quik REM4.5-NL SMD/SMT Chip Removal Alloy LF 4.5 FT (REM4.5-NL) - Amazon.com

Chip Quik REM4.5-NL SMD/SMT Chip Removal Alloy LF 4.5 FT (REM4.5-NL) - Amazon.com
www.amazon.com
 
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