DECISION MAKER
INSTRUCTION
SHEET
Price - Stock No 120
Check your kit
- 1 - 390R
- 2 - 1K2
- 2 -33K
- 2 -100K
- 1 - IN4002 power diode
- 2 - LED
- 2 -0.1uF greencap
- 2 - BC548 PNP
- 1 - slide switch
- 1 - push button
- Battery Snap
- P.C.Board
- 2 - MOLEX PINS
- Solder
- Hook-up Wire
Schematic Diagram
PCB Layout
BC 548
- Identify the resistors by their colour bands and an
Ohm-meter. Bend the legs so they fit the hole spacings, push
the legs through from the plain side of
the PCB and bend the legs to hold them in place. They may be soldered now if
you like.
- All other components can be fitted but observe the following:
- polarity of the LEDs. The flat on the flange must be
as the drawing shows.
- polarity of the transistors. The flat on the body must be as
the drawing shows.
- polarity of the power diode. The band must be at the K end
as the drawing shows.
- the red wire of the battery snap is soldered to the +ve pole on the
PCB. Use the two molex pins for these two connections.
- Refer Soldering
Technique
3. Test the circuit using a 9volt battery.
TROUBLE SHOOTING
If the project doesn't work then check through the following:
Make a visual check for missed
joints, components in the wrong positions,
and polarity wrong. This must be a very careful check making
constant reference to the component placement chart and the circuit diagram.
If you are sure that everything is correct (and that
your battery is not flat) you must suspect
that components have been heat damaged. This is unlikely because they
must be really cooked to sustain damage. However,
start with the LEDs; take them out one at a time, test with a
Circuit Tester (Kit available). DO NOT test LEDs
with a full 9volts;they will blow instantly. Meter the
current as follows:
- 9volts - use 390ohms in series
- 3volts - use 100ohms in series
Replace each component
carefully after it is tested.
Next, move to the transistors.
Simple tests can be made with an ohm-meter. Simply compare its readings
between the poles with those of a new transistor, or replace them to see if
new ones solve the problem. The other components will
not be troublesome unless they have been treated very harshly.
A SOLDER SUCKER TOOL,(a small vacuum pump)
or some DESOLDERING BRAID will help in the process of removing
components from the circuit board.