Electronics learning for hobbyists and students

Learning electronics tutorials for beginners is the primary goal of this site.

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Introduction to electronics

Illustrated current through resistors diagram by electronzap electronzapdotcom
Illustrated current through resistors diagram by electronzap electronzapdotcom
  • Voltage = Electrical pressure. The force needed to move electric current. One side is more positive and the other side is more negative. Those 2 points have a voltage diffence. A 9 volt alkaline battery has about a 9 volt (depends on how charged it is) difference between it’s positive and negative terminal. Negative terminal is typically called the 0V reference point or ground. While a 9V battery’s positive terminal is considered to be at 9 volts. So there’s a 9V difference between 0 and 9V. -Unit: Volts -Symbol: V

    Normally open (off) push button switch illustrative diagram by electronzap electronzapdotcom
    Normally open (off) push button switch illustrative diagram by electronzap electronzapdotcom
  • Current = Moving charges. Traditionally imagined as being a positively charged fluid going from more + to more -, and called conventional current. We still talk about current through a circuit in this way. Electron flow is what actually moves through a circuit. Electrons flow from more negative to more positive, and when studying what electricity is actually doing at an atomic level, you must use electron flow. -Unit: Amperage (Amp) -Symbol: A or I. Remember that a capital i looks like a lowercase L in many fonts.

    Ohms law voltage current resistance circle graph diagram by electronzap electronzapdotcom
    Ohms law voltage current resistance circle graph diagram by electronzap electronzapdotcom
  • Resistance = The opposition to current flow. Resistive components allow a certain about of current through them, based on their resistance and the voltage across them – I = V/R. This mathematical relationship is called Ohms law. -Unit: Ohms -Symbol: Ω (greek letter omega) or R

Circuits

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 
  • Light bulbs generate heat from the electrical current flowing through them. That heat emits light. Voltage must be limited to their rated value.
  • LEDs emit photons more directly from the current flowing through them. A proper resistor must be used based on the voltage to protect the LED. LEDs are more efficient than light bulbs, and more commonly used now.
Five volts across a series push button switch and resistor diagram by electronzap
Five volts across a series push button switch and resistor diagram by electronzap

Voltage across a pushbutton switch and a series resistor electronics demonstration by electronzap YouTube video

Simple pushbutton switch controlled LED circuit schematic diagram by electronzap electronzapdotcom
Simple pushbutton switch controlled LED circuit schematic diagram by electronzap electronzapdotcom

In video below:

  • Breadboard with 5V applied at the power rails.
  • Normally open (NO) push button switch: It is off until you press it.
  • LED: current must be limited to 20mA or less.
  • Resistor: For 5V, the 220Ω resistor in series with LED limits current to less than 20mA and keeps the resistor heat generation under 1/8W, which is recommended for the commonly used 1/4W resistor. for 9V supply I use at least 470Ω and for 12V supply I use at least a 1,000Ω (1kΩ) resistor.

 

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
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 

Batteries can be used to power the breadboard. They need a holder for cylindrical batteries, or a snap for the 9V version. The wires from the holder/snap can be plugged into the supply rails. If the wires are stranded (a lot of thin wires) then they will need to be twisted together first.

Using LEDs to “see” polarity

Simple polarity indicator circuit schematic diagram by electronzap electronzapdotcom
Simple polarity indicator circuit schematic diagram by electronzap electronzapdotcom 

Since LEDs only light up in one direction (forward biased), they can be wired in parallel but in opposite directions of each other and then in series resistor. Applying a voltage in either direction will light up the forward biased LED only.

Quick power supply polarity indicator LEDs circuit schematic to breadboard build

More in depth material

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

Diagram used in that video is at 001 Resistive component multimeter voltage-current-resistance 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.