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The schematic symbol of an LED (Light Emitting Diode).

Very brief description of a resistor and the resistor's schematic symbol.

General description of a push button switch and button switch schematic symbol. The push button is a momentary switch that will only cause its leads to connect when held in a pushed condition.

Schematic of a push button connected to a microcontroller. One lead of the push button is connected to a general I/O pin of the microcontroller and the other lead is connected to either ground GND or power VCC. If it is connected to ground, the pin should be set high, if the lead is connected to VCC, the pin should be set low.

Schematic on paper of one button with hardware debouncing and two LEDs (Light Emitting Diodes) connected to an AVR microcontroller. The push button switch is connected to pin 1 on PORT B and the LEDs are connected to pin 0 and pin 2 on the same port. These are green LEDs so a 330ohm resistor is used to limit the current through the LED.

7 LEDs are connected to PORTB pins 0 to 6. The 7th pin has a push button. On PORTD 7 LED are connected to pins 0 to 6 and on the 7th pin a push button is connected to the AVR microcontroller.

The AC (Alternating Current) first goes through a transformer to step down the voltage from the mains power (110v or 220v). The sine wave after the transformer is now a much more narrow sine wave, only peaking at the voltages corresponding to the transformer.

Rectification - using 4 diodes, or a bridge rectifier (which is 4 rectifier diodes) the sine wave portion that is in the negative region can be flipped up (or folding up) to the positive region. At this point, the AC looks more like hills rather than a sine wave. This happens because the diodes only let the current flow in one direction. The diodes are positioned and oriented in a way that makes both negative and positive portions of the sine way happen only in the positive direction.

The waveform (bumps) now need to be smoothed to match more like a line (DC). Adding capacitors will charge up like a battery and release the energy slowly. This creates a smoothing effect for the bumpy waveform.

To get the current to a specific voltage level to be used in the circuit, a voltage regulator is used. If a high dropout voltage regulator is used, the voltage level before the voltage regulator must be higher than the regulated voltage plus the dropout amount.

The potentiometer is a device that increases or decreases resistance as a variable resistor. Potentiometers can also be used as a voltage divider. If the potentiometer is to be used as a variable resistor, the potentiometer is only wired using two of the leads, the wiper (usually the middle lead) and one of the other leads (depending on which direction you would like the resistance to increase or decrease).

As a voltage divider, the two outer leads are aired to each pole and the center lead would be the output of the new divided voltage.

The potentiometer generally have three leads, two outer leads that hold the total resistance, and the middle lead as the wiper.

The schematic symbol for a battery actually looks like the battery. A standard battery has a little round notch on one end (the plus side) as does the schematic symbol.

The ground (GND) symbol should be drawn pointing down (like it's pointing to the ground). The positive voltage is best draw pointing up. This is a best practice tidbit. just because this is a best practice, don't go through all of your schematics and fix these symbols (unless you make the schematic public).

A voltage divider is just two resistors of a specified value to create a proportion for a voltage output that exists between the two resistors.

A transistor is a device that can allow a high current to pass with a small current signal. A transistor can work two ways, either as an amplifier, or a switch. In this case, it will be used as a switch to apply current to a relay.

The transistor has three leads. The lead that serves as an input of a small current is called the base lead. When the base lead gets a small current, current can pass through the collector and emitter leads.

Using your favorite Schematic CAD software (Eagle is used in this video), print the traces and pads on the glossy side of toner transfer paper. Make sure the scale is set to 1 (or 100%).

Don't touch the glossy side of the paper. If you do, the toner will not transfer in the touched area. Cut the printed portion out and cut a piece of copper clad to the same size as the printed design.

Clean the copper on the PCB with a regular dish washing scrubbing pad and some dish washing soap. The author of this video does not recommend using sandpaper.

This is the area the all of the projects, libraries, scripts and ULPs are located. Mainly, it is used to open a project, schematic or board layout or to create a new project, schematic or board layout.

To create a new project, right click on Eagle under Projects and click on new -> project. You can also create new folders, and then create projects under these folders.

To create a new schematic for the project, right click on the proejct that was just created and click on new -> schematic. The schematic editor will be opened automatically.

You can also create a new board with this method, but it is best to use the command in the schematic to do this, so all of the components in the schematic will fall under this board layout.

Generally, to open a schematic, just double click on the schematic file.

Once you click on the add tool within the schematic editor, a full list of the libraries will be shown in a dialog box. If nothing appears, or if a library is missing, go to the main window and right click the main libraries and select use all, or go to the specific library you want to use and right click on that library and click use.

There is a very broad variety of parts in the library. You will need to drill down to the part you need. You can also use the search.

Once you pick on a part, it will sow the part on the screen and you will need to place the part somewhere on the screen. It will allow you to place this part to many places if you wish. Press escape to stop placing the part, or click on the move tool.

The library dialog box will appear again is the escape key was pressed. If you don't need another part, just click on cancel.

Some parts will allow you to move specific sub portions of the part.

to move many parts at once, you will need to use the group tool. You can draw a rectangle around the parts, or click a polygon around the parts to be more precise in the selecting. Then you need to right click and select move group. If move group is not an option, you will need to click on move, then escape and right click again and the move group will be available.

The delete tool is shaped like an X on the left icon menu. As you select items to delete, the item will either disappear, or it will be highlighted so that you can confirm that it is the correct one to delete. The reason it will highlight is that there may be other parts, wires or nets nearby.

The copy tool looks like two stick figures. The copy tool allows you to copy a part or other item on the schematic and place it in another area of the schematic. This will repeat until you press the move tool, or the escape key.

The copy tool will make a copy of the entire part even if it contains many sub parts.

The Name tool will allow you to name the part, or name the net, or other feature that may be on the schematic. The behavior of the name tool will vary with the thing you are naming. If you name a net for instance, and another net has the same name, the two next will be considered as a connection between the two nets.

The value tool will allow you to specify a particular value for the part. This can be any value that you feel will help you in identifying the part for use in the project. For example, if a capacitor is on the schematic, it might need a value like 22 pF to specify the capacitance.

EasyEDA is a free, zero- install, cloud-based EDA tool, designed to give electrical engineers, educators, engineering students and electronics hobbyists an Easier EDA Experience. It is easy to use circuit design, circuit simulator and PCB design that runs in your web browser. https://easyeda.com/
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