Drawing 1: A single-channel
unit with its circuit side
Drawing 2 (below): The
component side is shown on
this single-channel unit.
Picture 2: A single-channel circuit
board’s component side—four paths
with 10 holes each with jumpers
Saw the board from the
prototyping perfboard material,
and make sure the saw teeth cut
from the circuit (copper) side first.
If cutting from the component
side, copper paths may be pulled
from the board.
I cut the boards by sawing
through the next set of holes
and then filing the edges smooth.
You can make seven boards at a
time from the 35 paths across the
Select and bevel one corner
as shown in Drawing 1. This will
give you an index mark to know
which end is up when you turn
the board over. You can put paint
or tape on the corner to serve as
an index marker if you wish.
Following Drawing 1, cut the
copper paths in seven places.
There is .06 inch of space
between holes. Try to remove
.015 to .02 inch of copper
centered between the holes. I use
it twice across the path in two places and then use the point
to pick the copper off the board between the cuts.
Using a permanent marker, mark the location for Pin 1 of
the 555 Timer IC on the component side of the board at the
hole indicated in Drawing 2.
Inspect the board to verify that the paths are completely cut
and a gap exists between the ends of the cut paths. The best
way is to hold the board up with the circuit side toward you in
front of a bright light.
Note that all jumpers, components, and wires are inserted
from the component side and soldered on the circuit side of
the board. Always wipe the old solder off of the soldering iron
tip before soldering each wire or component. I use a damp
cellulose sponge to wipe my soldering iron tip. Do not exceed
10 seconds on any one solder joint!
Cut to length, form, install, and solder two bare wire
jumpers as shown in Picture 2 and Drawing 2. After soldering
each component or wire, trim the excess length flush with the
solder on the board’s circuit
side (see Picture 2).
Cut to length two
insulated solid copper-wire
jumpers, strip both ends 1/4-
inch, then form, install, and
solder as shown in Picture
2 and Drawing 2. Form the
insulated wires around, not
across, the bare wires.
Warning: Before handling
any integrated circuit (IC)
or transistor, always touch a
grounded piece of metal to
reduce the chance of static
electricity damaging the IC
Proper IC orientation is
determined by the location
of the indexing notch in
the end of its case, which
is at the pin 1 end of the
package. Insert the 555
Timer IC on the component
side of the board with pin
1 in the proper hole. Start
one row of pins in their proper holes, then using the back side
of an X-Acto knife blade, press the other row of pins inward
to allow them to enter the correct row of holes. The spring
tension in the pins will hold the IC in position for soldering.
Verify that the pins are in the correct holes and that the
IC is down against the board or wires that pass under the IC.
Solder the IC pins on the circuit side of the board. Visually
inspect the board for solder bridges between paths.
Form the leads for each component as in Picture 3 and
install and solder as shown in Drawing 2. Install the 1N4148
or 1N914 diode with the black band located as indicated on
Drawing 2 and solder.
Cut a 1/4-inch length of heat-shrink sleeve and slide over one
lead of the 180K ohm resistor and against the resistor’s body.
38 Model Aviation JUNE 2015 www.ModelAviation.com