Electronics learning for hobbyists and students

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Page 2: More resistor/LED – Page 3: Capacitor intro

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Introduction to electronics

Studying electronics involves learning about circuits. Circuits are made up of one or more components, power source(s), and connectors, that have particular electrical, and other, properties.

Simple circuit powering an incandescent light bulb diretly from a battery illustrative diagram by electronzap electronzapdotcom
Simple circuit powering an incandescent light bulb diretly from a battery illustrative diagram by electronzap electronzapdotcom

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Light bulbs, not to be confused with LEDs, are simple components. They…

  • Convert a voltage into heat and visible light.

Therefore you apply the voltage that the light bulb is rated for, less voltage might be fine too, and you get light and heat from the light bulb. Too much voltage will burn it out.

You also need one or more conductive paths, connected in some way, so that electrical current can flow from one component to the others.

Continue reading below. Or watch the video below/visit this webpage https://electronzap.com/brief-switch-controlled-indicator-led-circuit/ which cover the LED circuit quicker.

Quick switch controlled LED circuit schematic to breadboard build

More modern lighting uses LEDs

LEDs produce light from electrical current more efficiently than light bulbs. They need a certain amount of voltage to conduct, but after that voltage current flows freely. Therefore, you need to make sure that current is limited somehow. Usually that is done with a resistor of high enough value.

Indicator LED Anode and Cathode schematic symbole illustrated diagram by electronzapdotcom of youtube and electronzap
Indicator LED Anode and Cathode schematic symbole illustrated diagram by electronzapdotcom of youtube and electronzap
  • Connect LEDs in the right direction/forward biased (anode more positive than cathode). They will not light up if connected backwards/reverse biased.
  • Limit current to no more than 20mA for most 3mm-5mm indicator LEDs. Can go as low as you want, LED just won’t be as bright.

Your first circuits will likely be built on an electronics breadboard. Under the plastic is rows of conductive connectors. Each side of the board typically has 2 separate conductive rows (red + and blue -) that usually run vertically the entire length of the board. The middle holes are connected 5 across and separated by a groove that usually runs down the entire length of the board.

Resistor protecting LED from 9V battery with battery snap on a breadboard drawing by Electronzap Electronzapdotcom
Resistor protecting LED from 9V battery with battery snap on a breadboard drawing by Electronzap Electronzapdotcom

Affiliate link ad. This is the breadboard I bought and use in my videos.

Continue reading below. Or check out the following video and/or webpage https://electronzap.com/002-diodes-especially-led-rectifier-forward-reverse-bias/ that covers the video in detail.

Electronics course 2 rectifier diode and LED forward and reverse biased explained with multimeter

Brief into to basic electrical properties

Although everyone wants to get right into building complex circuits that do amazing things, it is important to pay close attention to the electrical properties involved in order understand why, and to design circuits yourself.

  • Current: Charges flow through circuits. We can’t see current, we can only see the effects, or measure it with a meter. So, usually we visualize it as being like water flowing through pipes. The charges moving through an LED, for example, is what makes it light up.
  • Voltage: Electrical pressure. Again, we can’t see voltage, so it helps to imagine it as being like water pressure, but for electrical charges. You need a voltage to get current flowing based on a components electrical property. One side of a voltage is more positive, while the other side of a voltage is more negative. Batteries have a positive and negative terminal. Alternating current means the +/- polarities keep switching.
  • Resistance: An opposition to current flow. It takes twice as much voltage to get the same amount of current to flow through twice as much resistance. Twice the resistance gets 4 times as hot for a given current though, so it’s best to use as low of voltage as is practical.
  • Semiconductance: Conductance of a semiconductor component depends on any number of factors that must be learned.  Diodes for example, conduct current almost freely when one side (Anode) is more positive than the other (cathode), which is called being forward biased . They block current up to relatively high voltage when the Cathode is more positive than the Anode (reverse biased).
  • Voltage drop: The voltage needed to get a semiconductor to conduct, is taken away from the rest of the components.
  • Voltage division: Resistive components split up whatever voltage wasn’t dropped by semiconductors based on their percentage of the total resistance.
  • Power: The voltage and resulting current are converted into something. Mostly waste heat, but also light, spinning motor, sound, etc. depending on each component’s electrical properties.
  • Series components: Connected end to end.
  • Parallel: Both/all components have one terminal connected to the same point (node) at one side of the circuit, and another terminal connected to the same node of the other side of the circuit.

Simple LED circuit schematic

Instead of always drawing a pictorial like the one above, circuits are usually drawn as schematic diagrams.

Three common ways to draw a resistor protecting LED from 9V battery power supply schematic diagram by electronzap electronzapdotcom
Three common ways to draw a resistor protecting LED from 9V battery power supply schematic diagram by electronzap electronzapdotcom

The schematic symbol for the LED is the triangle with a bar on the pointed end, just like the rectifier diode, but also with arrows pointing away from the triangle symbol. The arrows can be thought of as the light that is emitted when current flows through it.

The LED is a type of diode (Light Emitting Diode). That means that it conducts current and lights up easily in one direction, while blocking current from common voltages (up to it’s breakdown voltage) in the other direction.

  • Forward biased (FB): Anode more positive than cathode. Diode/LED conducts easily once it’s forward voltage is reach.
  • Reverse biased (RB): Cathode more positive than anode. Diode/LED does not conduct at relatively high voltages. It’s breakdown voltage (when it starts conducting while RB) shouldn’t be exceeded for most diodes.

Continue reading below, or watch the following video! (video and diagram at 001 Resistive component multimeter voltage-current-resistance measurements )

Electronics course 1 Resistor component limiting current Ohms law and multimeter measurements

Resistor limiting current

LEDs need to have current limited through them or they will burn out. Usually the current should be limited to no more than 0.02A (20mA). The resistor is typically used to set the current through the LED or other components that need protection.

Current limiting resistor to protect LED basics diagram by electronzap electronzapdotcom
Current limiting resistor to protect LED basics diagram by electronzap electronzapdotcom
  • Ohms law for current: I=V/R
  • Ohms/power law for power (heat generated) by a component from a voltage and current: P=VI
Introduction to through hole 100 220 470 1K ohm resistor components color code electrical properties diagram for video by electronzap electronzapdotcom
Introduction to through hole 100 220 470 1K ohm resistor components color code electrical properties diagram for video by electronzap electronzapdotcom
Ohms law voltage current resistance circle graph diagram by electronzap electronzapdotcom
Ohms law voltage current resistance circle graph diagram by electronzap electronzapdotcom

One of the versions of the Ohms law formula (I = V/R ) explains what the current through a particular resistor will be based on the voltage across it. Current (I) equals voltage (V) across a resistor divided by the resistance of the resistor (R).

power

The (power) heat generated by the resistor is the voltage across the resistor times the current flowing through it (P=VI) and is given in units called watts (W).  The typically resistor is usually rated for 1/4W (0.250W).  That will make the resistor really hot though, and so it is recommended to always keep the wattage below half of the rated value as much as possible.

LED voltage drop

The LED, and other diodes, help the resistor limit current by reducing (dropping) some of the supply voltage from going across the resistor. Series (connected end to end electrically) components always split up/divide the supply voltage among them based on their voltage drop or their percentage of the total resistance after voltage drop are taken into account.

Diode LED component basic properties and schematic symbols diagram by Electronzap Electronzapdotcom
Diode LED component basic properties and schematic symbols diagram by Electronzap Electronzapdotcom

Page 2 – Electronics learning for hobbyists and students

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  • Information on this site is not guaranteed to be accurate. Always consult the manufacturer info/datasheet of parts you use. Research the proper safety precautions for everything you do.