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RRW1B • 11
12. Install U21, the PIC12C509A (marked RR). Make sure the notch indi-
cating pin one is in the same orientation as shown on the silkscreen and
Parts Layout Diagram. This is the “brains” of the RRW1B, generating your
38 kHz signal depending on the data seen from the receiver.
13. Install C26, a 0.1 uF ceramic capacitor (marked 104).
14. Install JMP1 using a spare piece of component lead formed into a sta-
ple like shape. Since this layout is on a single sided board, some routes
just couldn’t be performed without adding this jumper.
15. Install U20, the MIRCF001 IC (14-pin). Note the orientation of pin 1, it
is opposite of U21. Use the notch to align with the pin one indicator on the
IC itself. Make sure all 14 pins are through the holes before soldering.
16. Install R21, a 1M ohm resistor (brown-black-green) just above U20.
17. Install R20, a 100K ohm trimmer potentiometer (yellow top marked
104). This trimmer is used to set the squelch of the receiver so that con-
stant noise isn’t sent while data is not being received.
18. Install C25, a 1 uF electrolytic capacitor. Again check polarity before
soldering.
19. Install X20, the 3.3149 MHz crystal. This crystal is used as reference
by the receiver to set it to receive 433.42 MHz. Internal to this part there is
a Colpitts oscillator much like the one used in the RRW1A transmitter
board used to make the crystal oscillate.
20. Install C22, a 10 uF electrolytic capacitor. Again note polarity.
21. Install R26, a 22M ohm resistor (red-red-blue). Yes this resistor value
is very large. It is a “tweak” which prevents the data detect output from
swinging to the wrong direction when no signal is present and making it
look like it is always receiving a signal (a little quirk U20 tends to have).
22. Install C21, a 0.1 uF ceramic capacitor (marked 104).
23. Install C30, another 0.1 uF ceramic capacitor (marked 104).
24. Install C27, a 10 pF ceramic capacitor (marked 10 or 10K).
25. Install L20, a 33 nH four turn inductor. Be careful not to distort the
shape of the coil when installing it.
26. Install R24, a 100K ohm resistor (brown-black-yellow).
27. Install Q20, a 2SC2498 or C2570 UHF NPN transistor. This transistor
is used to help increase the reception range of your receiver by boosting
the signal seen at the antenna a bit more before going to the receiver IC.