© Jeds Peds
Brittania
Pa
ge
9
The same warning about heat when soldering diodes also applies to transistors. Take your time
not to overheat.
This board has pads for surface mount transistors too. The transistor uses 2 of the thru hole pads for
its front pins and the single rear pin is a SM pad. Through hole Jfets are a pain to source, surface
mount
aren’t
. To be honest, they aren
’
t that hard to solder either using tweezers and flux.
Trimmers
A trim pot or trimmer potentiometer is a small potentiometer which is used for adjustment, tuning
and calibration in a circuit.
This PCB design includes two positions for the single leg,
both are linked internally. Use which ever you prefer.
When it comes to using the trimmer, there is no
suggested setting on this pedal so experiment to see
what it does, and what you like.
This kit uses them to ‘bias’ the three JFETS. The supply voltage feeds into the top round pad,
measure between the rear pad and ground and set it to the individual value required (below).
Beyond that, tweek it until you find a sound you are happy with. The numbers are a starting point,
not a rule. Biasing takes experimentation at the test stage later on.
•
VR1 pad needs to be set to 6.0v.
•
VR2 pad needs to be set to 5.0v.
•
VR4 pad needs to be set to 5.5v.
I
’
ve added TP, test pads, around the board to help you do this.
IC’s
aka
‘chips’
IC’s
are small packages that contain many components. The ones that you will find in this kit will
have 8, or 16 legs.
On the PCB pin 1 will be marked with a * and there will be a small notch
drawn on the footprint. The solder pad for pin 1 will be square. The
socket will also have a notch. Be careful with the pins, they are fragile.
This is a socket. I do try to supply sockets for the chips, so unless I am
out of stock you should have one per chip. Solder these in place without
the chip, totally protecting the chip from heat. Please check you have all
pins through the pads before you begin soldering the socket.
