Learn tools of Electronics Invention
In this lesson we will learn tools to create electronics inventions. We will do this through a project to invent a measurement tool. As in all our inventing lessons we will learn through Minds On and Hands On activities.
Minds On Activities
The basic concepts of electronics, math of electronics. Also in the 21st century much of our electronics is embedded electronics meaning that much of the function is implemented in software so we will also be learning the code of electronics.
Hands On Activities
The project for this lesson is to Invent a piece of electrical test equipment, and improved digital voltmeter.
Not All Inventions Are New
Improvements to existing devices can be important inventions. Many devices list the patent numbers that protect their product. How does one device have so many patents you might ask. Well every improvement along the way gets patented. something simple like changing how the power cord connects to a device could be a great invention that solves a real problem. For some examples you can take a look at the site PatentlyApple here is a discussion of Apple patents etc.
So as we go through this lesson be thinking of ways to make an electronics measurement device better. Can you find an improvement that makes the device easier to use? More accurate? More compact? Less likely to break? ....
SCAMPER is a technique to invent based upon existing products. it is an acronym derived from:
- S = Substitute (playing basketball with a softball)
- C = Combine (toothbrush combined with a pencil to create a new product)
- A = Adapt (how would you eat your spaghetti without a utensil?)
- M = Magnify (how would your chair function if the legs were wider and longer?)
- P = Put to Other Uses (could your fork be used as a comb?)
- E = Eliminate (could you play tennis without a racket?)
- R = Rearrange (what if the laces of a shoe were placed on the bottom and not the top?)
here is a short video about SCAMPER.
Concepts of Electronics
Voltage is electrical potential energy. It can be compared to putting a ball on top of a hill. The ball is there and has energy but it is not doing anything until it rolls down the hill. The units used to measure voltage is the Volt which is the amount of energy per unit of electrical charge see this Khan Academy lesson on Electrical Units.
Current is the flow of electrical charge. This is like the balls rolling down the hill, now something is happening so this is how an electrical circuit can deliver power to a device. The more balls rolling down the hill the more current. Current is measured in Amperes or Amps which is just the amount of charge moving per second.
Resistance is how much a material or device resists the flow of electricity. The higher the resistance the less current that will flow at a particular voltage. Resistance is measured in Ohms which is Voltage divided by current or the number of volts that would drive a current of 1 ampere through the resistor.
Conductors are materials that have a low resistance and allow the flow of electricity. These are usually things like metal wires or metal parts. Things like salt water and some other liquids are also conductors.
Insulators are materials that have a high resistance and do not allow the flow of electricity. These are things like plastic, rubber, dry wood. Very pure water is also a good insulator, but add a little salt or acid and it quickly becomes a good conductor.
Electrical Circuit is the connection through conductors resistors and devices of a power source from a positive voltage to ground or zero voltage. A power source like a battery has a positive and negative side, or if it is a power supply it may have positive and ground. Ground (sometimes labeled as GND)is just another way of saying zero voltage. For current to flow we need to connect the positive side of the power source to the negative or ground. This will allow the balls to roll down the hill powering our devices. The amount of current that flows will be determined by the total resistance of the circuit.
Short Circuit is when the positive voltage is connected directly to the negative side or ground with a good conductor. This is Bad! it will allow a huge amount of current to flow possibly damaging the device or hurting you. so be careful when wiring your circuits to make sure the current is limited or used by your devices.
Math of Electronics
Ohms Law is the equation we use to determine the flow of current in a circuit. it is usually written as:
V = I * R
V is Voltage measured in Volts, I is the Current measured in Amps and R is the Resistance measured in Ohms.
From the equation you can see that there are 2 ways to increase the current in a circuit. Increase the Voltage or decrease the resistance.
Now that we know how electricity works we can better understand safety around electricity. We learned that electricity is about voltage, circuits and current. You do not want your body to become part of the circuit. Current through the circuit will affect devices in the circuit, you specifically do not want your heart to be one of the devices in the circuit. A very small current through the heart can kill you.
Fortunately for us our bodies are a high resistance that limits the amount of current that can flow, so when we are working with batteries of only a few volts there is no real danger of electrocution or even no danger of small shocks.
However, there is a real danger presented by the heat developed in the circuit specifically and accidental short circuit. In a short circuit a huge current can flow even at low voltages. The heat produced can burn you, melt plastic or start a fire. So always be aware of your circuit connections and use resistance to limit the current flow.
Higher voltage like what we have in the electrical outlets is enough to drive current through the human body so it is very dangerous. We should never work on any devices that are plugged into the wall and never make circuits that plug directly into the wall, leave that to the professionals.