Another old octave down circuit with a forest of transistors.... It also have a rare part, MFC-4040 which were a 4.pin divider/flip-flop IC. It went obsoltete in 1975 but according to several sources, NTE754 is a direct replacement. R12 and C21 is marked as "factory tailored component" in the factory schematic so these needs to be socketed and tested. And yes, there is a 1,4uF cap under Q4 but a 1,5uF will do.
Here is one for the Psychocandy fans. Just put this after your superfuzz clone (or to be more accurate, your "6TR" superfuzz clone) and go to town. The stock transformer part number is unknown but a 42TM013 will do with its 500mH inductance. Both 50k and 100k wah pots were used and input cap were iether 50nF or 10uF.
Schematic avaiable at Tonehome.
Here is an old odd cat. This is an all discrete clean monophonic octave down effect made by Shin Ei back in the early 70s. Initially I though this was a Maestro OB-1 clone but the schematics revealed that's not the case.
See the notes below the layout for components that needs matching for best result. And I must admit the switching is a bit confusing but I think I got it right. Also worth mentiong is that reducing the horizontal cap right to Q11 will give a more aggressive and louder octave down signal.
It was sold under several brand names like Pax, Rands and Sekova. Colorsound also made their own version called Octivider but it had a quite few value changes so that one deserves an own post.
*Update 240120* Verified by JRuss with a small correction. Pinout of Q77 altered to match the schematic.
Pedro (WTFiCanBuildMyOwnPedals) came up with this distortion/overdrive a while ago. It takes elements from both DOD250 and Boss DS1 but it has its own thing going on. A bit less gain than a DS1 and cap values in the signal path is adjusted. The hard clipping diodes are a LED and a silicon diode for assymetric clipping
This one is verified by Pedro.
This was a request. Appearantly a very powerful booster and eq circuit using inductors for sort of multiband wah sounds. The original ran on two 9v batteries for bipolar power operation but I included an onboard power inverter. Note that sizes of inductors varies a lot but hopefully there is enough room for them, especially the larger ones.
Schematic by Dirk Hendrik HERE.
This one is basically two OD circuits in one enclosure so I went with two separate board for the option to only have one in a smaller enclosure. The only differencies between the two channels is the value of the gain limiting resistor at the gain control, the hard clipping diodes and possibly the op amp (the one in the high gain channel was sanded off...).
The layout is based on a schematic avaiable at FSB.
Regular channel
Boss FZ2 has a very powerfull boost setting which is great for driving tube amps. It also has a powerful eq. Some people requested this, not wanting to build the whole FZ2 circuit which is quite big!
So here is two layouts, one stock with a FET input buffer and a discrete FET/PNP BJT op amp. The other one is Hyped Boost, the "cheat" version with a dual op amp for the input buffer and boost.
Here is a layout of an early version of D-120 OD. It is basically a J FET conversion of a Matamp GT120 with some interesting tweaks like diodes connected to the sources for some of the transistors. It also have a clean blend /summing amp circuit. The original had fixed resistors across drain and V for Q1 through Q3 but I replaced them with 50k trimpots for easier bias setup.
Note that the more recent revisions is a completely different beast circuit wise with a rotary switch, MOSFET transistors and a quad op amp.
Schematic avaiable at FSB.
Subbed the 6,8k Drain resistors for a couple of 50k trimpots for easier bias setup.
Analog Man's take on the old and quite rare Sam Ash Fuzzz Boxxx/Astrotone Fuzz. Bigger input and output caps and a resistor swap at the tone control should make this a different animal compared to the vintage pedals which suffered from lack of bottom end and a useful tone control. Various transistors has been used, often in "black dot" casing. Try NPN silicon with hfe 150-400.
Per request. A few things changed compared to the schematic; Bass ctrl outer lugs swapped, the two parallel 220uf power filter caps changed to a single 470uF (but you will get away with a 220uf or 100uf...), series protection diode added and bypass mute switching is omitted. SCHEMATIC.
