FM-100 Page 27
E. SWITCHED CAPACITOR FILTERS
1E. Locate the center of the board where this
group of parts is to go.
2E. Install R45, a 75K ohm resistor (violet-
green-orange).
3E. Install R53, a 1K ohm resistor (brown-
black-red).
4E. Install R52, a 75K ohm resistor (violet-
green-orange). This part stands upright.
5E. Install R81, a 75K ohm resistor (violet-
green-orange). Another stand-up.
6E. Install R66, a 15K ohm resistor (brown-
green-orange). This resistor isn’t actually associated with this section but it
forms part of the active lowpass filter in the next section. Another stand-
up.
7E. Install R77, a 75K ohm resistor (violet-green-orange).
8E. Install R82, a 1K ohm resistor (brown-black-red).
9E Install R61, a 4.7K ohm resistor (yellow-violet-red).
10E. Install R69, another 4.7K ohm resistor (yellow-violet red). This
resistor and R61 form a voltage divider for the MAX291 ICs opamps since
they need to run from the +5 volt supply. The divider creates 2.5 volts
which is the center voltage around the audio signal coming in.
11E. Install R78, a 10K ohm resistor (brown-black-orange).
12E. Install R56, a 10K ohm resistor (brown-black-orange).
13E. Install U10, one of the MAX291 filter chips. Make sure the part is
oriented correctly before soldering. Also make sure all eight pins are
through the board before soldering. It is a common mistake to install an IC
with one of the pins folded under the IC instead of through a hole.
14E. Install U9, the other MAX291 filter chip. Again check orientation and
the pins before soldering.
15E. Install C46, a 100pF ceramic capacitor (marked 100 or 101).
16E. Install C61, a .0047uF ceramic capacitor (marked .0047 or 472).
17E. Install C62, a .001uF ceramic capacitor (marked 102 or .001).
Содержание FM-100
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