BREADBOARDS,
CIRCUITS, AND
COMPONENTS (…OH MY)
By Nicole Tobias
Breadboards
Image src: Sparkfun
Breadboards: History
Prior to the 1960s,
A technique called wire-wrap would have been utilized.
Wire wrap is a process that involves wrapping wires around
conductive posts attached to a perfboard (a.k.a. a protoboard).
Image src: Sparkfun via Wikipedia
Breadboards: What’s in the name?
• So why call these things breadboards?
Image src: Sparkfun
Breadboards: Why do we use them?
• These solderless units are great for:
• Making temporary circuits
• Prototyping
• Testing out new parts
Prototyping
is the process of testing out an idea by creating a preliminary model from
which other forms are developed or copied, and it is one of the most
common uses for breadboards
Image src: Sparkfun
Breadboards: Anatomy
Circuit Basics
• Electricity wants to flow from a higher voltage to a lower voltage
• every source of electricity has two sides (often called terminals)
A simple Circuit:
Voltage, Current, Resistance, and Ohm’s Law
Electrical Charge
• Electricity is the movement of electrons.
• The three basic principles:
• Voltage
• is the difference in charge between two points.
• Current
• is the rate at which charge is flowing.
• Resistance
• is a material’s tendency to resist the flow of charge (current).
Voltage, Current, Resistance, and Ohm’s Law
When describing voltage, current, and resistance, a common analogy is a
water tank. In this analogy, charge is represented by the water amount,
voltage is represented by the water pressure, and current is represented by
the water flow. So for this analogy, remember:
Water = Charge
Pressure = Voltage
Flow = Current
Consider a water tank at a certain
height above the ground. At the bottom
of this tank there is a hose.
The pressure at the end of the hose can
represent voltage. The water in the tank
represents charge. The more water in the
tank, the higher the charge, the more pressure
is measured at the end of the hose.
Voltage
Voltage is the amount of potential energy between two points on a
circuit.
• Measured in volts
• Denoted in equations as ‘V’
Current
Current is the amount of charge flowing through the circuit over a
period of time.
• Measured in Amperes (usually just referred to as “Amps”).
•
An ampere is defined as 6.241*1018 electrons (1 Coulomb) per second passing
through a point in a circuit. Amps are represented in equations by the letter “I”.
• The higher the pressure, the higher the flow
Resistance
• In electrical terms, this is represented by two circuits with equal
voltages and different resistances.
The circuit with the higher
resistance will allow less charge
to flow, meaning the circuit with
higher resistance has less current
flowing through it.
Ohm’s Law
• Ohm defines the unit of resistance of “1 Ohm” as the resistance
between two points in a conductor where the application of 1 volt
will push 1 ampere, or 6.241×1018 electrons.
• usually represented in schematics with the greek letter “Ω”
• The formula (Ohm’s Law):
𝑉 =𝐼 ∗𝑅
Where
• V = Voltage in volts
• I = Current in amps
• R = Resistance in ohms
Ohm’s Law Experiment
• http://www.us.kingbright.com/images/catalog/SPEC/WP7113LID.pdf
• You will need to get out the following things from your kit:
• An LED (red)
• Wires
• Power Supply packet
Hook up the Power-Barrel
in the following way:
Ohm’s Law Experiment (Cont.)
• Why is the following design bad?
Ohm’s Law Experiment (Cont.)
We need to determine the appropriate
sized resistor for the circuit…
Looking at the Datasheet our LED is:
• RED
• 2mA, or 0.002 Amps
Now let’s figure out the resistor…
Ohm’s Law Experiment (Cont.)
Use the Formula:
Therefore,
Using our values,
Solving for resistance,
𝑉 =𝐼 ∗𝑅
𝑉
𝑅=
𝐼
9𝑉
𝑅=
0.002𝐴
𝑅 = 4500Ω
*4.7k Ohms will be sufficient to use here
Success! We’ve chosen a resistor value that is high enough to keep the
current through the LED below its maximum rating, but low enough that
the current is sufficient to keep the LED nice and bright.
Ohm’s Law Experiment (Cont.)
*4.7k Ohms will be sufficient to use here
Breadboards: Supplying Power
<Pull out your kits and lets set up the power supplies.>
You will need:
1. 9v Battery
2. Barrel and Connecter
3. Wires
(1-3 probably already hooked up from the experiment)
4. Capacitors (100uF and 10 uF)
5. Regulator (3.3v)
Breadboards: Supplying Power
Breadboards: Supplying Power
*Note: Our regulars are for 3.3V instead of 5V. Just be aware of that in the following diagrams
Breadboards: Supply Power
• At this point we should probably discuss Polarity…
• This is something we have to consider with many of the
components that we will be working with.
Polarity
Polarity indicates whether a circuit component is symmetric or not.
• A non-polarized component – a part without polarity – can be
connected in any direction and still function the way it’s supposed
to function.
• A polarized component – a part with polarity – can only be
connected to a circuit in one direction.
• If a polarized component was connected to a circuit incorrectly,
• At best, it won’t work as intended.
• At worst, an incorrectly connected polarized component will smoke, spark, and
be one very dead part.
For our components, it is generally the case that the short lead is
ground and the long lead is power. We saw this earlier.
Breadboards: Supply Power
• Now we must add the Capacitors.
• http://www.youtube.com/watch?v=3b7mjukhTyQ
• A capacitor is a two-terminal, electrical component.
• Known for their ability to store energy; they’re like a fully electric
battery.
Breadboards: Supply Power
• At this point we should probably discuss Polarity…
Breadboards: Building your first circuit.
• The circuit goes as follows:
• There is a wire connecting the 3.3V power rail to one leg of an LED.
• The other leg of the LED is connected to a ? resistor. (figure this out)
• The resistor is then connected to a button.
• When the button is pushed, it connects the circuit to ground completing the
circuit and turning on the LED.
Breadboards: Building your first circuit.
• What resistor do we need?
3.3𝑉
𝑅=
0.002𝐴
Solving for resistance,
𝑅 = 1650Ω
Breadboards: Building your first circuit.
Yet another video…
• http://www.youtube.com/watch?v=k9jcHB9tWko
Let’s try some Logic Gates…
• Not
• AND
• OR
• NAND
• NOR
•…
“Normal” Circuit
Not Gate
AND Gate
OR Gate
NAND Gate
AND Gate (Chip) Example
Resistor Color Code Chart
What resistor is this?
• Look at the colors and use chart on previous slide…
Yellow = 4
Violet = 7
Brown = 1
Gold = (tol) +/- 5%
Formula =
first_second * 10^third
So, 47*10^1 = 470 Ohms with
a tolerance of +/- 5%
Data Sheets
• Transistors (2N3904)
• Regulator 3.3V
• Capacitors
• 10uf
• 100uf
• LEDs
• RED
• Yellow
• Green
• AND Gate Chip
• OR Gate Chip
• Atmega168 Chip
• Breadboard Intro
N555 .pdf