4
The
3PRR
is a combination of two utility circuits onto a single PCB: a charge pump / voltage inverter
and bypass switcher. The switching mechanism is true bypass with effect input grounded, and the
charge pump section can p or – 9v, +18v (unregulated) and/or +15v (or +12v) regulated. All
outputs can be used simultaneously, if needed, so long as the circuit load does not exceed the
current supply available through the charge pump. This ranges from 20mA-100mA depending on the
charge pump used.
Building tips:
The 3PDT switch and components are mounted on the
same side of the PCB
(the one with the
component silk screen). The entire assembly is flipped over to mount in the enclosure.
The 9v output is a courtesy output. This can be used if you are building two effects in a larger
enclosure that have different power requirements. Example: a boost that uses 18v and a compressor
that uses 9v. In this case, the 9v pad and G pad would be wired to the compressor. The 18v pad and
the other G pad would be wired to the boost. You should be able to combine positive and negative
ground effects, too. Example: a fuzz that uses -9v and a boost that uses +9v.
You can use any of the following charge pumps: MAX1044
CPA
, TC1044
SCPA
, ICL7660
SCPA
, and
the LT1054. There are two small pads connected to pins 1 and 8 of IC1. These pads must be
jumpered for all the charge pumps EXCEPT the LT1054.
Do not jumper the pads for the LT1054.
Special note: These pads were masked over by the manufacturer; they are still solder-able
since they are plated through. Just heat up the jumper and let your solder flow into both pads.
This wiring diagram shows what you will see inside the enclosure.
