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Breadboard
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Breadboard is a good tool for
beginners to build and test circuits without need of soldering and a proper PCB
(Printed Circuit Board). It is also known as solder-less board. As the name
suggests, it is a board usually white in color (not mandatory) having huge
number of holes in it similar to porous edible bread. Every hole is having metallic
contact under it to connect with component’s leg inserted into it. Each hole
with connector is connected internally in a specific fashion to build a circuit
easily. This board comes in different size, small and big. Distance between
each hole is typically 0.1inches (2.54mm) which is suitable to plug most of the
electronic components including transistors and ICs which are designed with
same gap between their pins.
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Breadboard Internal Connection
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If we see the internal design,
there are two row at top and bottom, used as power supply rails. As shown in picture,
they can be marked with ‘Red’ and ‘Blue/Black’ color or may not be marked.
As
shown here, the horizontal rows are connected internally as marked by red and
blue boxes. Both rows are separate so that can be used as positive and negative
supply rail and do not short inside. There is a break in the middle of the
board, if we need to use the full length as power supply rail, we need to
connect jump wires or jumpers to connect complete top row. Same applies to the
bottom two rows also.
Similarly, each vertical rows
marked as ‘A’ to ‘E’ are internally connected (as shown by vertical red boxes) but
isolated with adjacent vertical row. Again there is a horizontal gap in the
middle of board, hence ‘E’ to ‘I’ are connected to each other but isolated with
adjacent vertical rows as in top half.
We also need jump wires
(sometimes called jumper wire) to connect some rows or columns with other as
per the circuit requirement. We get these jump wires in different colors to
differentiate each other. They can have male pins at both end or male at one
end and female header at other end and third type with female header on both
sides. Different types of wires are used at different places as per
requirement. Female headers are used mostly to connect components whose pin
distance doesn’t match with breadboard holes distance or they are bulky to be
connected directly to breadboard. Rest of the requirements is fulfilled by male
header wire at both sides.
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| LED Circuit |
Let us build our first circuit on
breadboard where we connect two cells, one resistor and one LED as we saw in
LED topic. To hold two cells together is series, we use a pencil cell holder
made of plastic. Both cells are connected in reverse, the negative side towards
the metal spring. Finally we get 3V at the output of this holder. We connect
positive wire to top row, so the top row acts as positive rail. Similarly, the
negative terminal is connected to second row acting as negative rail.
Now insert one leg of resistor to
any hole in top row and second leg of resistor in any vertical row. In the same
vertical row we insert anode of LED and cathode of LED to adjacent free
vertical row. This way the anode of LED is internally connected to resistor
terminal. To connect negative supply to cathode of LED use a jump wire from any
hole of vertical row in which cathode of LED is inserted and connect the other
end of jump wire to negative rail on top. This way, we could assemble the LED
circuit on a breadboard with soldering the components on any PCB.
Keep watching for next topic,
comments are most welcome to improve posts.
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