Frequency Central Seismograf Manual

Frequency central
Build documentation for:
Seismograf
Featuring code by Jetroid
Main PCB Control PCB
Seismograf is a PIC based drum module featuring coding by Jetroid. There is currently a
choice of two PICs which may be used with Seismograf, ‘BD‘ and ‘SD‘. As you might expect,
BD contains a range of 8 bass drums, while SD contains a range 8 of snare drums. The drum
sounds are 10 bit encodings of some of our favourite electronic kits from yesteryear. It is not
possible for the user to load their own sounds onto Seismograf PICs, but there is a chance
that we may release alternative drum sets as the years roll (!) by.
Key to PCB screen print:
n: This signifies NPN BC547 transistors. Note the correct pinout as shown by the half circles.
The PCB shows the correct orientation for BC547. Other similar transistor types can be used,
but please observe the correct pinout.
Please observe the correct polarity of the diodes and electrolytic capacitors.
Reduce value for brighter LED
Diode clamping network to
protect CV inputs to the PIC
from over-voltage. CV Inputs
respond from 0V to 5V.

Bill of Materials
1K x 4
4K7 x 1
10K x 4
47K x 1
100K x 3
220K x 1
All resistors ¼ watt
metal film.
22pF x 1
100nF x 2
10uF x 1
47uF x 2
SEISMOGRAF PIC
TL072 x 1
BC547 x 1
1N4148 x 9
78L05 x 1
3mm red LED x 1
14 pin IC socket x 1
8 pin IC socket x 1
B100K x 3
3.5mm socket x 5
Male header x 1
(cut to size)
Female header x 1
(cut to size)
Power header x 1
Knob x 3
Main PCB assembly
1. Solder the diode and all resistors
2. Solder all two IC sockets
3. Solder the non elecrolytic capacitors
4. Solder the 78L05 –watch the polarity!
5. Solder the box power header. Make sure the notch lines up with the screenprint
legend. If in doubt, have a look at a power cable, and make sure when inserted into
the header the red stripe lines up with the -12V screenprint.
6. Solder all electrolytic capacitors.
7. Cut male headers to size and solder them into place. Make sure that they stick out of
the bottom of the PCB.

Control PCB
1. Solder the 3 potentiometers, use the panel to make everything line up nicely.
2. Place all sockets on the PCB, making sure the ground tabs line up with the PCB’s
ground pads, then place the panel over them. This will assure that the sockets are
correctly positioned. Flip the whole lot over and solder the sockets into place. Use
cut off resistor legs to connect the sockets’ ground tabs line up with the PCB’s
ground pads.
3. Cut female headers to size and solder them into place. Make sure that they stick out
of the bottom of the PCB.
4. Place the LED in position into the PCB. Present the panel to the PCB, flip the whole
lot over, make sure the LEDs stick though the holes in the panel, solder in place.
All done! Go bang your drum!
You can use a Sharpie to write ‘BD’or
‘SD’on the white rectangle on the
Seismograf panel. You can easily
remove the ink with nail varnish
remover without harming the panel
graphics.
RDH 11/01/20
https://www.frequencycentral.co.uk/