How to Use Breadd Board.....
BREAD BOARD....
A breadboard (protoboard) is a construction base for prototyping of
electronics. The term is commonly used to refer to solder fewer breadboards (plug
board).
Because the solderless breadboard does not require soldering, it is reusable.
This makes it easy to use for creating temporary prototypes and experimenting
with circuit design. Older breadboard types did not have this property. A
stripboard (veroboard) and similar prototyping printed circuit boards, which
are used to build permanent soldered prototypes or one-offs, cannot easily be
reused. A variety of electronic systems may be prototyped by using breadboards,
from small analog and digital circuits to complete central processing units
(CPUs).
Connections on Breadboard
Breadboards
have many tiny sockets (called 'holes') arranged on a 0.1" grid. The leads
of most components can be pushed straight into the holes. ICs are inserted
across the central gap with their notch or dot to the left.
Wire links can be made
with single-core plastic-coated wire of 0.6mm diameter (the standard size).
Stranded wire is not suitable because it will crumple when
pushed into a hole and it may damage the board if strands break off.
The diagram shows how
the breadboard holes are connected:
The top and bottom rows
are linked horizontally all the way across as shown by the red and black lines on the diagram. The power
supply is connected to these rows, + at the top and 0V (zero volts) at the
bottom.
I suggest using the
upper row of the bottom pair for 0V, then you can use the lower row for the
negative supply with circuits requiring a dual supply (e.g. +9V, 0V, -9V).
The other holes are
linked vertically in blocks of 5 with no link across the
centre as shown by the blue lines on the diagram. Notice how there is
separate blocks of connections to each pin of ICs.
Large Breadboards
On larger breadboards there may be a break halfway along the top and bottom
power supply rows. It is a good idea to link across the gap before you start to
build a circuit, otherwise you may forget and part of your circuit will have no
power!
Building a Circuit on Breadboard
Converting
a circuit diagram to a breadboard layout is not straightforward because the
arrangement of components on breadboard will look quite different from the
circuit diagram.
When putting parts on
breadboard you must concentrate on their connections, not their
positions on the circuit diagram. The IC (chip) is a good starting point so
place it in the centre of the breadboard and work round it pin by pin, putting
in all the connections and components for each pin in turn.
The best way to explain
this is by example, so the process of building this 555 timer circuit on
breadboard is listed step-by-step below.
The circuit is a
monostable which means it will turn on the LED for about 5 seconds when the
'trigger' button is pressed. The time period is determined by R1 and C1 and you
may wish to try changing their values. R1 should be in the range 1k
to 1M.
Time Period, T = 1.1 × R1 ×
C1
IC pin numbers
IC pins
are numbered anti-clockwise around the IC starting near the notch or dot. The
diagram shows the numbering for 8-pin and 14-pin ICs, but the principle is the
same for all sizes.
Components without suitable leads
Some components such as switches and variable resistors do
not have suitable leads of their own so you must solder some on yourself. Use single-core plastic-coated wire of 0.6mm diameter (the
standard size). Stranded wire is not suitable because it will crumple when
pushed into a hole and it may damage the board if strands break off.
Building the example circuit
Begin
by carefully insert the 555 IC in the centre of the breadboard with its notch
or dot to the left.
 |
| Monostable Circuit on Breadboard
|
Then deal with each pin
of the 555:
|
1.
Connect a wire (black)
to 0V.
|
2.
Connect the 10k resistor
to +9V.
Connect a push switch to 0V (you will need to solder leads onto the switch)
3.
Connect the 470 resistor
to an used block of 5 holes, then...
Connect an LED (any colour) from that block to 0V (short lead to 0V).
4.
Connect a wire (red) to
+9V.
5.
Connect the 0.01µF
capacitor to 0V.
You will probably find that its leads are too short to connect directly, so put
in a wire link to an unused block of holes and connect to that.
6.
Connect the 100µF
capacitor to 0V (+ lead to pin 6).
Connect a wire (blue) to pin 7.
7.
Connect 47k resistor to
+9V.
Check: there should be a wire already connected to pin 6.
8.
Connect a wire (red) to
+9V.
Finally...
- Check all the connections carefully.
- Check that parts are the correct way round (LED and
100µF capacitor).
- Check that no leads are touching (unless they connect to the same block).
- Connect the breadboard to a 9V supply and press the
push switch to test the circuit.
If your
circuit does not work disconnect (or switch off) the power supply and very
carefully re-check every connection against the circuit diagram.
