# Phys204 Lab10 Intro to circuits .pdf

### File information

Original filename: Phys204_Lab10_Intro to circuits.pdf

This PDF 1.5 document has been generated by TeX / MiKTeX pdfTeX-1.40.11, and has been sent on pdf-archive.com on 19/10/2016 at 00:49, from IP address 149.4.x.x. The current document download page has been viewed 348 times.
File size: 451 KB (6 pages).
Privacy: public file

Phys204_Lab10_Intro to circuits.pdf (PDF, 451 KB)

### Document preview

Phys 204
Lab 11: Intro to Digital Circuits

In this lab we are going to build basic circuits to demonstrate how digital circuits are
put together and developed.
One of the most important tools in this, and upcoming labs, is the breadboard. Breadboards are a way to prototype and experiment with circuit design without having to
solder components, which makes them convenient and reusable. Inside the breadboard
are metal connections that bridge rows or columns to establish an electrical connection
between components as follows:

Figure 1: Connections in a breadboard
The long rows on the top and bottom of the breadboard are usually reserved for positive
(red) and (negative) power connections. The columns in the middle are free to connect
components.

Resistors
We use resistors to regulate the voltage over certain components and don’t destroy them.
For example connecting a light-emitting diode (LED) directly to a 9V battery will cause
1

Phys 204: Lab 11

2

destroy the LED almost immediately because it cannot handle so much power. Therefore
we put a resistor in front of the LED to divide the voltage over the LED accordingly.
For most cases with LEDs a 1kΩ is sufficient.

Figure 2: Resistor code

Exercises
1. System.out.println(”Hello World!”);
The “Hello World” equivalent is a a simple circuit with a power supply, resistor and
LED. In all circuits we are going to use a 1kΩresistor.
Complete the following circuit:

Phys 204: Lab 11

3

2. Parallel circuits
The way breadboards are designed they make adding components in parallel simple and
convenient. For components to be connected in parallel the all the heads of the components (anodes) must be DIRECTLY connected to all the heads of the other components,
AND ALSO, their tails (cathodes) must all be connected DIRECTLY connected to each
other.
Complete the following circuit, first by adding one LED, then a second one to your
previous circuit:

Phys 204: Lab 11

4

3. Series circuits
To create a circuit in which components are connected in series, the head of one component must DIRECTLY connect to the tail of another, with nothing else in between.
Complete the following circuit, first by adding one LED to a circuit with one LED, then
add two, for a total of 3 LEDs, as shown in the diagram:

4. Series-parallel circuit
A series-parallel circuit involves components in which some are in series with each other,
and other are in parallel. Almost all circuits in everyday life fall into this category.
In the following example LED 1 and LED 2 are in series with each other because the
head of LED 1 is directly connected to the tail of LED 2. We will treat the resist before
the LED and the LED as one component for the purpose of simplicity. In the example
we can also see that LED 1 AND LED 2, which since we have said they are connected
in parallel we can treat them as one, say LED 1-2. Led 1-2 are in parallel connection
with LED 3 since the head of the LED 1-2 is directly connected to the head of LED 3,
AND, the tail of LED 1-2 is directly connected with the tail of LED 3.
Complete the following circuit:

Phys 204: Lab 11

5

Is there any difference in the brightness between LEDs 1, 2 or 3? Explain your answer.

5. Potentiometer
The potentiometer acts as a variable resistor, with resistance between two given values,
controlled using a dial.
Complete the following circuit:

What happens to the brightness of the LED as you turn the dial on the potentiometer?

Phys 204: Lab 11

6

6. RGB LED
The red-green-blue LED, inside there are 3 LEDs with a common cathode, therefore are
4 connections to the LED (anode for red, green and blue, common cathode).
Complete the following circuit:

What colour does the LED shine? What happens when you pull out one of the resistors.

Extra credit
the red, green and blue LEDs. Draw a circuit diagram of your circuit in your lab report.
What happens when you adjust the potentiometers?