Ramsey Electronics STC1 Instruction Manual - page 13
STC1
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38. Install C46, a 470pF ceramic capacitor (Marked 470 or 471).
39. Install C45, a 100pF ceramic capacitor (Marked 101).
40. Install C25, a .001uF ceramic capacitor (Marked .001 or 102).
41. Install C6, a .001uF ceramic capacitor (Marked .001 or 102).
42. Install X1, the 6.00MHz crystal (Metal can marked 6.000).
43. Install Q1, the 2N3904 type small signal transistor. Observe the correct
orientation of the flat side.
You have just completed the 6MHz oscillator section of the PC board. This
circuit is called a Colpitts oscillator, and is very good at producing the voltage
levels and frequency we need to see at the inputs of U6, the CMOS type ‘D’ flip-
flop. Also notice that this circuit’s accuracy is not important when it comes to
filtering audio, and can be off by as much as 10% with no problems at all, but
this oscillator will run at better than .01% accuracy without even aligning it!
Now we will begin installing the sound processing circuitry which allows us to
control bass, midrange, and highs.
44. Install C1, a 100pF ceramic capacitor (Marked 100 or 101).
45. Install C18, another 100pF ceramic capacitor (Marked 100 or 101).
46. Install C23, a 10uF electrolytic capacitor. Pay close attention to polarity!
47. Install C38, a .01uF ceramic capacitor (Marked .01, 10n, or 103).
48. Install C20, a .047uF or .05uF ceramic capacitor (Marked .047, 473,
.05, or 503).
49. Install C5, a 10uF electrolytic capacitor. Polarity!
50. Install C36, a 100uF electrolytic capacitor. Again pay close attention to
polarity. This is another capacitor that helps to “smooth” out the power
supply.
51. Install C2, a .047uF or .05uF ceramic capacitor (marked 473, .047, .05,
or 503).
52. Install R4, a 10K ohm resistor (brown-black-orange).
53. Install R9, a 3.3K ohm resistor (orange-orange-red).
54. Install R32, another 3.3K ohm resistor (orange-orange-red).
55. Install C7, a .0047uF or .005uF ceramic capacitor (marked .0047, 472,
.005, or 502).