LEDman vs. The Cads -- kgull's Mutron II PCB.
Before I get into what a mess I made of things with this build: Major kudos to Kgull for an amazing layout.
I had one problem after another with this build. I fired it up the first time and my rate indicator blinked but not the one for the effect. Scratch my head, poke everywhere, remove and replace some chips ... woops put a TL in backward and popped an LT1054. Crap. Toss it. Poke around some more, eventually get the bright idea to remove the LED and test it ... oh, it's a dead LED. Toss it.
Replace the LED. Something not working now. What the heck? Oh crap, I mixed up the leads on the power and ground when I plugged them back into the breadboard. Popped another 1054. Replaced ... oh crap, I had popped the Zener a minute ago, didn't I? Replaced it.
Everything's finally working in the LFO. Plug in all the audio chips ...... only dry sound, no phasing. Well that's weird. Do some audio probing, figure out that one of the chips must be dead. Unfortunately, I'm out of TL072s, and I only have a couple TL062s. Replace the chips one by one until I get audio at the phaser section ...
Put one in backwards. Smoke from the 1054.
ARG. Replaced.
Go to box the thing up, and here's where it gets really stupid:
(a) I wanted to use up this box, but I had already drilled it. It's got an extra hole. Hey, I'll just add a dry lift for a vibrato mode. More on that in a minute. Annnnd my rate LED won't reach.
So I desolder the rate LED, add legs ... resolder and ...
What the? Now the rate LED isn't blinking. I pull it and test it ... still works. Look all over the board. Eventually (not even lying -- like a half hour to find this) I find the lifted trace, after scraping away a bunch of solder mask and being completely unable to find the trace to pin 2. Resolder ... still not working. Huh. Somehow managed to blow the LED WHILE TESTING IT. Replaced. Finally everything's working again.
(b) The Lumin board is the only optical bypass that will fit. And it's masked on both sides ... so of COURSE I put it on the switch upside down. And I don't figure this out until after I had wired everything backwards. But I get everything soldered up, test the bypass, everything works.
Oh, I forgot ... I wanted polarity protection. Desolder the power wire and install a 5817 between the jack and the switch PCB. You might guess where this is going ...
Plug in ... nothing. Not even the bypass LED. How is that possible. 0v on all the power pins. What the hell?
Eventually -- again, not even joking, at least a half hour -- I figure out that I'm getting 9V at the input on the board because my probe is hitting the lead of the diode itself, and I see that I lifted the pad for the power trace on the Lumin. Desolder the diode, use a new one and go to the other side of the switch (thanks for putting two pads, Rej & Jason!).
Finally ready to go.
With that much troubleshooting defeated, I felt a bit like a superhero, so I went with a comic book theme (Baltimore Comicon is next weekend, too, though I'm not going).
If you don't get the pun in the name of the pedal, most photocells use Cadmium Sulfide, abbreviated as "CdS." So, the enemies are the cads, crowding around LEDman.
As for how it sounds, it's different enough from the other phasers I've made that I think it's worth a build. (I prefer the Stage Fright overall for intense phase, I think.)
I used Smallbear's 9203 photocells. These have a high dark resistance; I found that to get the most out of this pedal, having the LED go darker gave a more pleasing sweep on the treble side of things. I actually used a 2K trim for the LED limit, and it's dialed almost all the way up; I also have the 10K balancing trim past noon. The sweep sounds a little lopsided no matter what, but this gives a really wide sweep and seems to get the most out of the circuit.
My one mod was the dry path lift, to create a pitch vibrato effect. I don't think this was worth it. It's a subtle difference with the Regen fully CCW and sounds kind of interesting -- but it's basically unnoticable at higher regen settings except that a very small amount of extra bass comes back in when in phaser mode. It's possible that there was a better way to implement the mod and maybe lifting the Regen as well would have helped make the Vibe setting more noticeable, but I couldn't do that with only a SPDT, and I couldn't fit a two pole switch.
