Applied Electronics

Learn to understand the basics of electronics.

Electronics underpins the operation of many types of machinery used in horticultural practices. Lawn mowers to tractors and computer controlled irrigation to refrigeration of produce: equipment used by horticulturists uses electricity.

Lesson Structure

There are 8 lessons in this course:

1. Nature and Scope of Electronics Linear, Analogue and Digital Electronics??
2. Measuring Electricity
3. Passive components (resistors capacitors, inductors
4. Circuits
5. Other Components -Diodes, Transistors, Semi conductors, Integrated circuits, Switches, ???
6. Input and Output devices – Cameras, keyboards, speakers, lights, monitors???
7. Digital Electronics
8. Applications - Working with Electronics

Learn to Understand, Measure and Better Use Electricity

Multimeters – and how to use them

Multimeters can be an analogue or digital device that is used to measure the current, resistance and volts through electrical components. There are usually various settings on a multimeter that you can change the type of current measurement you desire to find.
Using a multimeter you can check a battery to make sure it is fully charged or how much charge is left, you can check resistance between a device, you can use one to also diagnose faults in electrical systems by checking for breaks in the current flow. 

There are different symbols you will see on a multimeter that are used to determine the type of application and system your measuring

• “V” represents Voltage or volts
• “A” represents amps
• “Ω” represents ohms

There are also the symbols for size of measurements:

• “µ” (micro unit) is One Millionth 
• “m”(milli) is one thousandth
• “k”(kilo) is one thousand
• “M”(mega) is one million
  
  

How to use a multimeter

Multimeters have a main unit with two wires that plug into it, COM(ground) and a “V” positive + wire that have small probes at their ends, black for COM and red for voltage. These probes are used to directly touch electrical components to check voltage, current, resistance and also continuity.

You will see on a multimeter a dial that can be turned to different settings. 
These relate to measuring either voltage, current or resistance, they all have different meanings and settings. 
When you see DCV or a “V” with a bar above it, this will measure a DC voltage, ACV or a “V” with a ~ squiggle above or next to it, this will measure AC Voltage.

Selecting the correct setting for the application is important to get a correct reading, understanding the results can help you determine information about the electrical device or circuit being measured.
Forming connections in a series or parallel
These are the two ways that you can measure the current. 
Depending on the type of circuit you connect the probes in either a series or parallel configuration. In a series circuit the current will be the same across each component, where as a parallel circuit will have the same voltage across each component. 
With series circuit each device or element will have the same current but may not have the same voltage
With parallel circuit each device or element will have the same voltage but may not have the same current.

Measuring voltage

With your two wires plugged into COM and “V or A”, first choose the correct voltage setting on the multimeter for the application that your trying to measure. If you are measuring something like a 12V battery, a setting of 200 would be too high; selecting 20 would give an accurate reading.
Take the red and black probes and touch them on the positive and negative corresponding electrical contacts. For example, for a light bulb, you would hold the red wire on the bottom of the bulb and the negative on the side of the bulb, or if the bulb is LED then on the red and black wires from the bulb. You will see on the output screen a value indicating how much voltage is flowing at that point to the circuit or from the power source.
If you were to measure the positive and negative terminals of the power source and then the output component and received a lower reading at the component or no value, then it could mean a break or weak current in the wires connecting the battery to the component.

Measuring current

First set your multimeter to the correct setting for the application.
Connect your probes in a series configuration to measure the current in your device. Basically meaning that the red probe will go to the positive end of the source power and the negative probe will go to the positive terminal of the component your measuring, the negative terminal of the component goes back into the power source negative terminal, which forms a loop of current.

Measuring resistance

The first thing to note is if the component you are trying to measure has a power source applied. If so, then you will need to disconnect the power source before testing resistance. Your multimeter can provide a small amount of power that will be used to make the measurement.
Turn the multimeter dial to the “Ω” symbol range.
If you know the resistance of what your trying to measure it makes it easier to test as you can turn the dial to measure the correct values.

ELECTRICITY IS FUNDAMENTAL TO MANY JOBS

Electricity is used everywhere; from machinery to computers and lighting to environmental control. Any workplace that uses a light, vehicle or computer of any kind will be using electricity, and by doing this course and better understanding how to apply electricity at work, you will be better able to work with electricity.