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EDF1• 7
EDF1 PC BOARD ASSEMBLY STEPS
Remember to save at least one clipped off component lead for use as a
jumper later in the construction process.
1. Let’s start with U2, the NE555 timer. The NE555 repeatedly starts the
oscillator that produces the dripping sound. Install it down at the bottom
middle of the board. Be sure to line up the notch on the board drawing
with the notch on top of U2 and be sure you’re not installing the other IC
(both have 8 pins)! Also be sure that all leads are through the board be-
fore soldering.
2. Next, install C13, 1 uF electrolytic capacitor, next to U2. Make sure its
polarity is correct. The “+” on the board has to line up with the positive
side of the cap. Usually, it’s the “-” side of the cap that is marked. The
other side is “+”.
3. Install C6, 2.2 uF electrolytic capacitor, next to C13. Watch polarity
again.
4. Install C12, 220 uF, electrolytic capacitor, above C6. Watch polarity.
5. Install R9, 2 ohm resistor [red-black-gold], above U2.
6. Install C11, .1 uF ceramic disc capacitor [marked 104], above R9.
7. Install U1, LM386N above C11. This is the audio amplifier that drives
the speaker you connect.
8. Install C8, 10 uF electrolytic capacitor above U1. Watch that polarity.
9. Install C9, 220 uF electrolytic capacitor, next to U1.
10. Install C10, .01 uF ceramic disc capacitor [marked 103], to the right of
U1.
11. Install R8, 100K ohm potentiometer [orange top marked 104], to the
left of U1.
12. Install C1, .1 uF ceramic disc capacitor [marked 104], to the left of U1.
13. Install C5 and C4, .01 uF ceramic disc capacitors [marked 103], to the
left of R8.
14. Install R2, 5K ohm potentiometer [orange top marked 502], to the left
of C4.
15. Install R3, 47K ohm resistor [yellow-violet-orange], under R2.
16. Install Q1, 2N3904 [marked, oddly enough, 2N3904], under R3.