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noting the cathode (negative) side of the diode. Install as shown in the
parts placement diagram (D6 is adjacent to the power switch S1).
19. Moving again towards the lower right of the main circuit board
(component side view), find the position for U6, the other 555 timer IC.
Install U6, the 555 timer IC. Make sure to align the notch or dot associ-
ated with pin one with the notch shown in the parts layout diagram.
20. Install R34, 33K ohm (orange-orange-orange).
21. Install R35, 33K ohm (orange-orange-orange).
22. Install C21, .1uF disc capacitor (marked 104).
23. Install C23, .0047uF disc (marked .0047 or 472).
24. Install R37, 10K ohm (brown-black-orange).
25. Install C22, .001uF disc capacitor (marked 102).
Now that wasn't so bad was it! You've just completed the power supply and
oscillator section of your direction finder. Pretty soon you will be searching
for fox transmitters in baby strollers at the mall!
Let's get back to it. Next we'll work on the digital filter section of the circuit.
Be sure to mount the components as close to the printed circuit board as
possible to provide for reliable operation.
26. Install C14,C17,C16,C15, all .1uF disc (marked 104). Now you're
starting to roll along.
27. In the same manner, install C10, C12, C11, and C13, again, all .1uf
(marked 104).
It is time to install some of the logic IC's. Please note that although signifi-
cant advances have been made in modern day CMOS technology, static
precautions should be observed while installing these IC's. Be sure to orient
the IC band or notch as shown in the parts diagram for each IC. Try to focus
on the individual IC pin as you're soldering and "walk" the iron to consecutive
pins of the IC as you continue.
28. Install U5, the 74HC4051 IC. Make sure not to "bridge" solder be-
tween the pins.
29. Install U8, the 74HC42 IC. Solder all 16 pins.
30. Install U12, the 74HC14 inverter IC.
31. Install U7, 74HC161 IC. Watch that orientation!
DDF1 • 16
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