If you want to be able to select between Grit and Non-Grit, then install a
4.7k
Ω
resistor in R21, and also solder one end of a 1.1k
Ω
resistor to one end of
the 4.7k
Ω
resistor. Solder the free end of the 1.1k
Ω
resistor to one of the leads
of the final toggle switch. Solder the remaining lead of the toggle switch to the
other end of the 4.7k
Ω
resistor.
____ Audio Output Jack
Finally, solder a 6-to-8-inch wire to each of the two solder lugs on the
audio output jack. The lug which connects to the TIP connection is the Audio
Signal, and the other lug is the Audio Ground. Solder the other end of the Audio
Signal wire to the hole marked P2 on the PCB. Solder the Audio Ground wire to
the hole marked P12 on the PCB.
____ Insert the TL084
Insert the TL084 Op-Amp integrated circuit into the socket marked U1 on
the PCB. Take note that there is a notch on the integrated circuit at one end.
Make sure this notch faces the end of the socket nearest the “U1” label. (It
should match the notch in the socket, if you installed the socket correctly.)
You may need to carefully bend the pins on the chip; they tend to be sprung
fairly heavily from the chip factory. This is because, normally a chip would be
inserted by a machine, and the extra springiness is required by the insertion
machine. Since we’re installing by hand, you may need to use a pair of needle
nose pliers to bend the pins slightly inward to make it easier to install into the
socket.
____ Insert the CD40106
Insert the CD40106 Hex Schmitt Trigger integrated circuit into the socket
marked U2 on the PCB. Again, take care to align the notched end of the chip to
the end of the socket nearest the “U2” label on the PCB. It should match the
notch in the socket.
____ R12 and R15
There are two resistor locations on the PCB marked “See Text”. Do not install
these resistors.
Page 14
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