Ramsey Electronics SCA1 User Manual - page 12
SCA1
•
12
13. Install R4, 220K ohm [red-red-yellow].
14. Install Q1, the 2N3904 transistor. The PC board drawing shows how the
flat side of each transistor points in relation to other parts. To install a
transistor, press its three leads in place as far as they go without forcing. The
wires may be spread as needed to hold it in place before soldering. Don’t
hesitate to use sufficient soldering heat to make good connections.
15. Install R2,10K ohm [brown-black-orange]. Be sure to save some of the
component leads that you clip. You’ll need them later to make jumper wires.
16. Install C7, .001 disc [marked .001 or 102].
Take some time now to re-check your solder connections. Be certain that there
are no solder bridges between components or foil runs. Make sure all component
leads are trimmed. Re-solder any connection which is less than perfect.
BUILDING THE VOLTAGE CONTROLLED OSCILLATOR
17. Install R3, 2.2K ohm [red-red-red].
18. Install C2, 10uf electrolytic capacitor. Electrolytic capacitors are polarized
and must be installed correctly. They are usually marked with a black stripe
and a (-) indicating their negative lead. PC boards will usually indicate the (+)
hole.
19. Install C21, another 10uf electrolytic capacitor. Observe correct polarity.
20. Install R5, 10K ohm [brown-black-orange].
21. Install R6, 10K ohm [brown- black-orange].
22. Install R7, 10K ohm [brown-black-orange].
23. Install U1, the LM565 PLL IC. Use care when inserting the IC into the
circuit board not to bend one of the pins so it doesn’t pass through the circuit
board. Note also that one end of the of the IC is marked by a dot, notch, or
band; this end must be oriented as shown on the PC board layout diagram.
24. Using a scrap lead, install a test point in the TP1 position. Usually, it is
best to bend the wire in a loop at the top so it is easy to connect to when a
test is required.