Orange Unit: A Person-Centered Launch
1B: Introduction to Electronic Circuits
Background Knowledge Probe
Write a list of the electronics that you make use of on a regular basis.
- Who comes to mind as the designers of these?
- What parts, inside and outside the hood, were used to build each one? To use it?
- What have you done with any items that started to work less than optimally?
Technical Introduction
Example: A Single LED Circuit
An electrical is a path in which electrons flow from source to ground. The source is usually measured in (the force, expressed in volts) or (the flow, expressed in amps). A (expressed in ohms) controls the flow of this source.
When I water my garden from a rain barrel, a full barrel has more pressure than one that is almost empty. That full barrel is the equivalent of a higher voltage , for instance, one that is 240 volts. A barrel two-thirds of the way full may be more like a 120 volt power source, while a nearly empty rain barrel may be closer to a 5 volt power source.
If I have a spray nozzle hooked up to my rain barrel, I can often use a lever to increase or decrease the water’s flow. This is equivalent to the current of the power source. Some of my water hoses are 1/2″ thick, while some are 3/4″ thick. This is equivalent to bigger or smaller ohms of a resistor, respectively, since a thinner hose increases the resistance of the flow of water compared to the thicker hose.
As a side note, in electrical engineering, provides a basic equation I=V/R. This states that current (I) is equal to voltage (V) divided by resistance (R). And as all Trekkies know from their days with Jean-Luc Picard, resistance is not futile, it’s essential! Beyond this, don’t worry if you are ready to put aside these particular details.
are commonly used to draw out the path used by the electronic components to complete a circuit.
As an example, the Fritzing image above is a schematic with three electronic components:
- a battery
- a resistor
- a
The lines between are not electronic components, but rather are some form of conductive material like a metal wire that is used to carry the current from component to component. In the schematic, a positive current leaves the 9 volt battery and passes through a 560 ohm resistor before connecting to the positive charge of a 10mm white LED. From there, it passes through the negatively charged leg of the LED to the ground connection of the 9 volt battery, completing the circuit. Only when this circuit is fully and properly completed and the battery has sufficient charge to dispatch a current will the LED turn on. (Schematics and diagrams in this book were primarily created using the open source program Fritzing.)[1]
Schematics don’t tell us anything about how the circuit is actually built, and indeed the visuals for the different components needed are confusing artwork until their interpretation is provided. But with a little bit of practice, schematics become a unique conceptual information source. We