Links
  Here are some other sites that are likely to be helpful to effects builders:  
  GEOFEX - The Guitar Effects-Oriented Website. R. G. Keen's essential resource for effects DIYers.  
  The Analog Music Zone - Jack Orman's site has several original schematics and some vintage ones, and he offers other original designs on CD.  
Aron Nelson's Forum - Deservedly very popular. Schematics, FAQs and links. The Forum is frequented by a lot of nice people, including some of the most knowledgeable serious amateurs and professionals in the field.
Tonepad - Francisco Peņa has proved that distance is no barrier to spreading great designs! Check out his projects and ready-to-solder PC boards.
GeneralGuitarGadgets - J. D. Sleep's well-documented projects, schematics, ready-to-solder boards and construction information are all here. There are a number of other schems that I've not seen anywhere else, as well as information on talk boxes, spring reverbs and tube pedals.
BYOC - "BuildYourOwnClone" offers full kits for many classic pedals, with pre-drilled enclosures and ready-to-solder PC boards. Especially check out the Wah pedal kit!
Analog Man - "Analog Mike" is well-known for new and vintage pedals, schematics and mods. Also check out his forum for ideas on making best use of your gear.
For Musicians Only - Tom Hughes offers the encyclopedic Analog Man's Guide To Vintage Effects as well as new and used gear. The book is worth buying just for the interviews with people like Mike Matthews, Roger Mayer, Zachary Vex and others.
SSGuitar - A forum and resource with an emphasis on design and construction of solid-state amplifiers.
VodkaMods - Mod services, modded versions of commercial pedals, kits for doing your own mods.
PedalDoc - Spanish-language site for mod kits.
ProAnalog - Scott Smith's custom-built and vintage pedals.
North Star Audio - Tom Lanik manufactures the Pro Pot wah-wah pedal upgrade pot. He also represents Stuart Castledine and does repairs and mods. Nice guy, very knowledgeable, and a regular contributor to the effects newsgroup. He is developing a web site and is available by email at tomlanik@earthlink.net.
Loop-Master - Passive signal routers, loopers, and switchers in many configurations, and true-bypass pedals.
Dirk Wacker - Singlecoil.com has lots of interesting FX, amp and guitar mods, and an on-line store full of specialty parts.
Howard Davis - When I'm out of my depth with a repair or design problem, this is the guy I visit. Designer of many vintage Electro-Harmonix pedals, now does repairs and consulting.
Stompin-Ground - Pedal boards, cases, racks and cable systems.
Tonefrenzy - Custom pedals, and a large library of sound clips of classic effects.
GuitarElectronics - Pickups, preamps and MIDI interfaces, specialty pots, switches and other guitar parts, and wiring diagrams.
DIY Guitar Site - Many links to guitar, equipment and music resources.