Before we begin, a couple of notes:
dramatically—perfect.
Yes, this circuit has an actual
transformer in it. And if you’ve ever
seen a transformer, you know there’s
a bit of bulk involved. The Octavia
transformer isn’t enormous by any
means, but may be tall enough to
where you can’t close the enclosure lid
if the circuit board sits atop the backs
of the potentiometer. I’ve taken the
liberty of placing the transformer on a
small “daughterboard” with wires that
connect to the main board. This means
that you can tuck the transformer
anywhere it will fit within the enclosure.
I’ve also included a lift switch to
remove the octave-up sound from
the circuit, leaving only the fuzz. It’s
extremely easy to implement, takes up
almost no room and changes the sound
Also, the effect works best with
matched diodes. Without getting too
far into the technicals, diodes have one
numerical property we care about, and
that is forward voltage. For octavetype effects, the forward voltages
of the diodes must be as close as
possible. I have a Peak Atlas DCA55 to
measure this (and many other things)
for me, so matching is easy. If you
continue to build pedals, these tools
are indispensable and cost about $80.
If you don’t want to invest in one, you
may need to purchase a pre-matched
pair from eBay, or just roll the dice, buy
two and hope they match. If they don’t
match, the pedal will still work, but the
octave will be a little less pronounced.
WITH THAT SAID, HERE'S WHAT YOU'LL
NEED FOR THE CIRCUIT BOARD...
PARTS NEEDED:
RESISTORS
• 1x 220 ohm
• 1x 470 ohm
• 1x 1k
• 1x 1.2k
• 1x 22k
• 1x 47k
• 1x 180k
• 1x 220k
44
DIY //
Build Your Own Tychobrahe Octavia
• 1x 680k
• 1x 820k
CAPACITORS
• 1x 150pF, ceramic
• 1x 1nF (1000pF, 0.001uF),
ceramic
• 2x 100nF (0.1uF) film
• 1x 22uF
• 2x 33uF
• 1x 220uF