31. Insert U1, the micro-controller marked with a sticker labeled DCI1 into the socket. Orient the notched end as shown on the PC board silkscreen and Parts Layout Diagram (toward the relays). Before you push it down into the socket, check to be sure none of the pins are bent under or outside of the socket. When you’re sure the pins are where they belong, press the chip down so that it is seated flat within the socket. 32. Install C2, a .01µF ceramic capacitor (marked .01, 103 or 10 nF). Disc capacitors are not polarized so they can be installed in either direction. The reason we call them “disc” caps can be seen by the package style.
The capacitor itself is two conductive discs separated by a dielectric compound. 33. Install C1, a 470 pF disc capacitor (marked 470 or 471). This capacitor couples over a bit of the X1 clock signal from U3 to run the micro-controller. 34. Install C10, a .1µF ceramic capacitor (marked .1 or 104). Have you figured out what that 104 value stands for yet? Here’s the answer. Disc capacitors are typically marked with their value in picofarads, or pF (commonly pronounced “puff”), equal to a value of 1x10-12 Farad. A 104, or 100,000 pF disc cap (notice how 104 breaks up as a 1, 0, and then 4 more 0s to equal 100,000) has an equivalent value of 0.1 microfarad or 0.1 µF.
Mathematically speaking, 100,000 x 10-12 = 0.1 x10-6. That’s how we switch between the 104 and .1 values so easily. 35. Install R6, a 330K ohm resistor (orange-orange-yellow). 36. Install U3, the 18 pin DIP tone decoder chip marked HT9170B. Make absolutely sure it is mounted in the proper direction. The small semi-circle (or notch as commonly called) on the IC represents pin 1 and should be mounted in the same direction as in the Parts Layout Diagram. The ICs in this kit are not mounted in the same direction so look closely before soldering it in. 37. Install JMP1 using one of the scrap wire leads you saved from the earlier steps.
Form the wire into a staple like shape and insert it from the top side of the board in the holes shown on the silkscreen and the Parts Layout Diagram. Solder it in place so that it will act like an electronic bridge connecting the circuit traces over the top side of the circuit board. 38. Install JMP2 in the same fashion as the last step. 39. Install C8, a 22 pf ceramic capacitor (marked 22). 40. Install C7, another 22 pf ceramic capacitor (marked 22). 41. Install R21, a 10K ohm resistor (brown-black-orange). 42. Install X1, the 3.579 MHz crystal (silver can marked 3.579). Make sure it is flush to the board before soldering. 43.
Install R4, a 100K ohm resistor (brown-black-yellow). DCI1 • 15