SP-1
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8
4. Solder all connections unless directed otherwise. Use enough
heat and solder flow for clean, shiny, completed connections.
Don't be afraid of any pen-style soldering iron having enough heat
to damage components.
5. Trim or "nip" excess wire lengths after soldering.
1. Install S1, the on-off switch, simply press it into position and solder all
six points. This switch is the equivalent of the telephone "hook"or handset
button. Incoming calls are answered by pressing S1.
2. Similarly, install S2, the Mute switch. This switch can turn off the
microphone circuit without breaking the phone connection, providing a
privacy or "hold" function.
3. Install R18, the volume control. It may have three of five soldering
points, with the optional outer two tabs offering additional mechanical
rigidity. Solder all points.
4. Examine J2, the modular telephone jack. Press its pins into their
correct PC board location. Notice that the outer support posts are plastic
and are not to be soldered. If you anticipate heavy use of this jack
(frequent cord changing, moving, etc.) use a dab of glue to secure J2
before soldering. Solder all 4 connections for modular jack J2. If you look
closely, you'll see that only two pins are actually used in the circuit.
5. Examine the subminiature jack (J1) supplied for speaker connection. It
fits into the PC board position easily. Notice that the tab nearest to the
edge of the board is connected to the common ground of the circuit. The
other two tabs are connected together to the SP1's speaker audio output.
You have a choice of installing J1 supplied or your own speaker wire,
depending on your intended application. Install J1 or a suitable length of
your own speaker wire.
6. Examine the audio transformers, T1 and T2. Notice the red marking on
one side of the top insulator on each unit. These marked sides must be
pointed toward the center of the board, as shown by the dark sides for T1
and T2 on the PC board drawing. For each transformer (they are identical
units), a total of six solder connections should be made. The outer 2 tabs
are soldered to common ground for mechanical rigidity. Install
transformers T1 and T2.
Completion of your SP1 requires installing over 20 "jumper wires," designed
JMP1, JMP2, etc. These simple wire bridges are formed from scrap bare wire
snipped from resistors, capacitors or diodes. Unless you have a handy supply
of bare, tinned wire, be sure to save all cuttings for these jumper wires.
Jumper wires allow a single-sided PC board to have the benefits of a double-
sided PC board without the extra cost.
7. A choice to make:
