Here’s another octave down effect; the Shin-Ei Octave Box. I based this on the schematic from Topopiccione, with a slight modification to the octave switch (grounding R36 when it’s not connected to input). If you build this using substitute transistors, mind the pinout.
Going to build an octave up for a friend and came over this one when looking around. Not sure what this sounds like or whether it’s any good, but worth a try maybe?
Based it on a schematic found in this thread over at FSB. I’m guessing the diodes should be matched for best effect.
Update (02.07.2013): Now verified as working, thanks to Mortua.
Put together this one tonight on an impulse. I’m guessing this is pretty similar to the Tycobrahe Octavia. I’m thinking the diodes should probably be matched for best effect, and I’m unsure about the orientation of the drive pot so you might have to re-orient it (let me know and I’ll update the layout).
Update (15.01.2013): Already verified thanks to Alex. The drive pot was reversed, but the layout has been updated.
I’m taking a guess this is an octave fuzz of some kind. Let me know if this works and what you think of it 🙂
Update (11.11.2012): Built this one tonight and found, as was reported, that Q3/Q4 were slightly misbiased. I changed R12 from 1K to 2.2K according to another schematic and this solved it. There’s also the option of changing R17 from 10K to 4.7K instead, thanks to Mrlindell for that suggestion.
For no particular reason I just thought this one seemed interesting. Supposedly it emulates the sound of a sitar. Though I’m not expecting anything profound it’ll be fun to try it out.
I’m hoping the transformer will fit (looks like the same size as the one for the Octavia).
Update (25.05.2012): Now verified as working, thanks to zottel.
I have no idea what this sounds like. The schematic I based this on (thread at FSB) isn’t complete so I made a few assumptions. I chose not to include the last diode pair, and went with the rectifier in the power section.
Update (07.07.2012): Reoriented the Drive pot. It should now work as advertised, thanks to Alex for verifying!
Update (12.02.2013): Thought this thing sounded great and decided to box it. Graphic is a bit on the naughty side, and I swear the input indicator was not intended!
Based this on a schematic I found on FSB of unknown origin utilizing the 2SC828 transistor (notice pinout on this one). I found another schematic as well using 2N2222s and slightly different resistor values, but chose to go with the 2SC828 one. Here’s to hoping it checks out!
Oh, and I’m pretty sure this’ll fit in a 1590B enclosure 🙂
Update (10.11.2012): Built this one myself tonight. I didn’t have any 2SC828 transistors, but used 2N2222’s with no problems (just watch the pinouts, had to bend the legs a bit), so I can happily say that this works.
Here’s a vero layout for the Boss OC-2. I based this partly on a factory schematic from Boss, a modified schematic for a “chopped” version by Ben Milner and an alternative schematic (using the 4027 IC) by Stellan Lehrberg.
Update (28.05.2011): I populated an OC-2 vero board based on my layout yesterday, and it really didn’t work well. After a little debugging I realized my layout had Q1 and Q2 the wrong way. Correcting this really improved things, but there was still an issue of each pot interfering with the two others. Lehrberg’s schematic differed from Boss’ factory schematic in that he had placed 100k resistors in series with each #2 lug. This seemed to do the trick!
Update (16.08.2011): Boxed this one up tonight. What a fun and cool effect! Recommended 🙂
Update (20.10.2011): Fixed dead layout link.
Update (26.10.2011): A request for voltage readings have been made. I thought I might as well post them here for everyone:
Battery at 9.05v, all pots fully clock wise, effect on, but no signal. Battery after measurements at 8.83v.
I’m being liberal with the ground voltages as some of them were a few millivolts. Also pins 9-13 on IC5 fluctuated quite a bit, but neither are in use so this shouldn’t matter.
Update (08.11.2011): Corrected IC4, pin #5 reading which was a typo (9v).
Update (10.11.2011): There were obviously a couple more mistakes so I re-checked everything and updated the above voltage readings.
Update (19.02.2013): Darren reports that 2N5457 and 1N60 works well as a substitute for 2SK30A and 1N34A respectively (mind the pinout on the 2N5457).
Update (23.09.0213): Here’s the modified schematic for this layout.