Assembly Instructions

ASTABLE BLOK
PCB ASSEMBLY INSTRUCTIONS
Copyright EduTek Ltd – Rev. 2
Circuit Details
The circuit is shown below with a parts list of components.
Check through this list and identify each component.
Copyright EduTek Ltd
Label
R1
R2
R3
VR1
C1,2
Component Name
10KΩ resistor
4.7KΩ resistor
1.5KΩ resistor
100KΩ potentiometer
10uF electrolytic capacitor
No.
1
1
1
1
2
C3
C4
IC1
220nF polyester capacitor
10nF polyester capacitor
NE555 Timer IC
1
1
1
Miscellaneous
Push-on knob, green
8 pin DIL IC holder
3 way header plug
Jumper
2 way PCB terminal block
3 way PCB terminal block
Tinned copper wire
No.
1
1
2
1
2
1
5cm
ASSEMBLY
Below is the PCB with no components.
The markings show the number and outline of each component.
Before starting, check through the following:
• Ensure you have safety goggles and adequate ventilation.
• Use a soldering iron stand with a damp sponge to clean the iron tip regularly.
• Use some small Wire-cutters to remove excess wire and have some snipe-nose pliers.
Wire Links
There are 2 wire links to insert. You can form these from the tinned copper wire.
Cut the wire in half using wire-cutters and shape each piece using snipe -nose pliers, to fit the
holes as shown below.
Make two links using
the hole spacing on
the PCB as a guide.
Insert them into the PCB
bending the legs outward
slightly to keep them in place.
Resistors
There are 3 resistors, all are a different value. They must be inserted in
the correct place but can be inserted either way round. Bend the legs
near to the resistor body at 90 degrees to ease fitting into the PCB.
R1 = 10KΩ, (Brown, black, orange, gold)
R2 = 4.7KΩ, (Yellow, violet, red, gold)
R3 = 1.5KΩ, (Brown, green, red, gold)
IC Holder Socket
The IC holder allows easy insertion of the IC later on. It should be soldered with
the notch on the top facing upwards. This will match up with the IC later on.
To stop the IC holder falling out when you are soldering it, bend over two legs in
opposite corners. They are quite short so there is not much wire to bend. Take care
not to stab your finger.
Capacitors – non-polarised
There are 2 non-polarised capacitors, C3 and C4.
Because they have no polarity, they can be inserted either way round.
These capacitors
may also be
cream in colour.
C3 = 220nF, (marked as ‘.22’)
C4 = 10nF, (marked as ’10n’)
Terminal Connector Blocks
There are 2 sets of terminal blocks.
The 3-way fits on the right hand side with the openings facing outwards.
The 4-way is made from 2 x 2-way connectors and fits on the left facing outwards.
Slide one 2-way connector down the side
of the other so the grooves fit together.
Header Plug
The header plug enables different settings for the circuit.
The 3-way headers fit next to each other on the PCB.
Once soldered, you can fit the jumper vertically on any of the 3 settings.
Capacitors – polarised
There are 2 polarised capacitors, C1 and C2, both 10uF electrolytic type.
They have polarity and MUST be inserted the correct way round with the
longer wire inserted into the hole marked “+”.
There are 2 ways to identify the polarity of an electrolytic capacitor:
• The positive connection is the longest wire.
• The negative connection has a silver stripe above it on the casing of the capacitor.
Potentiometer
The potentiometer has 3 pins that insert into the PCB from above. The pads
underneath the PCB are enlarged so you can add plenty of solder when
soldering these pins.
Once soldered, set the
potentiometer halfway.
Then with the green
stripe facing upwards,
push the knob onto the
shaft of the
potentiometer.
Integrated Circuit – IC
Finally insert the IC with the notch facing upwards, to match the IC holder.
Take care that all the pins of the IC are properly located into the holder.