Here are the steps I would recommend to assemble the boards:
1)
Populate the boards with all parts, starting with the smallest to the tallest. Solder in the pots and rotary switch
last.
Notes:
Use sockets for the IC’s, at least for the TAPLFO
Depending on the kind of caps you use, you may need to lay down your electrolytics flat on the board to
gain space. I made sure to leave enough space on the board to accommodate the lying caps.
R18
is the current limiting resistor for the Tempo indicating LED. The indicated value of 10k is what I am
using with white super-bright LED’s. Choose the value that will be best for your particular LED. I would
recommend a super-bright as they will draw less current and reduce the chances of inducing ticking.
C22
is used to smooth out the sharp corners of the LFO signal and remove some spikes that can produce
audible clicks especially with sharper edged wave shapes. You might not necessarily need it. It depends on
your particular Optocoupler and whether you like the signal to be chopped real hard or not. I suggest
socketing that cap, trying without it first and then start with a low value like 20n until you find a value that
removes the tick but does not round off the square wave too much.
C3
and
C4
define the High Pass and Low pass cut off frequency. If my calculations are right, with the values
indicated in this document, the Low pass cuts at 664.3 Hz and the Hi pass at 780.6 Hz. You can of course
experiment with other values.
LED1
is there to increase the output of the voltage regulator (5V + the Forward voltage of the LED). Try to
find a LED with no more than 2V FWD voltage to make sure the voltage regulator still has enough drop out
voltage to operate correctly. Note: the silkscreen shows the flat side the wrong way around. Follow the –
and + signs for correct orientation.
C14
– one of the 22p caps next to the Crystal are labeled wrong. On the PCB it shows C16, when it should be
C14:
Once soldered, cut the components’ leads as short as possible to minimize the space needed between the
two boards
