Electronics learning for hobbyists and students

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

Quickly familiarize yourself with the following topics. They will make more sense as you learn about more circuits.

This page is constantly being updated as I try to make it easier to understand. Some topics may be covered twice until I remove the less desirable version.

Basic electrical properties

Voltage pushes current through a circuit. The resistance and/or voltage drops, of the individual components limits the amount of current that flows.

Voltage:

9V battery typical 0V reference ground location diagram by electronzap electronzapdotcom
9V battery typical 0V reference ground location diagram by electronzap electronzapdotcom
  • Electric potential.
  • Unit: Volt
  • Symbol: V.
  • Tip: When you think of electricity flowing through circuits as being similar to water flowing through pipes (water analogy), voltage behaves much like water pressure.

An unused 9 volt (9V) battery provides approx. 9 volts. up to a certain amount of current for a certain amount of time. It’s voltage goes down mostly based on how much current it has provided over a period of time.

The voltage of a single cylindrical cell (still commonly referred to as a battery) depends on  it’s chemical make up.

Single cell battery common appearance and nominal voltage diagram by electronap electronzapdotcom
Single cell battery common appearance and nominal voltage diagram by electronzap electronzapdotcom

Connecting batteries in series adds up the voltage produced by each of them. You should connect them in series when they are at the same voltage and have the same mAh capacity.

Series batteries add up their voltage illustrative diagram by electronzap electronzapdotcom
Series batteries add up their voltage illustrative diagram by electronzap electronzapdotcom

An adjustable (bench) power supply provides a reliable voltage as long as it is plugged into the wall and too much current isn’t asked of it.

Current:

  • Electric charge flow.
  • Unit: Amp (usually milliamps in basic electronics). One amp (1A) is a coulomb of charge passing part of a circuit every second. 0.001A is the same as 1mA.
  • Symbol: I
  • Water analogy tip: Electric current through a circuit is similar to a liquid being pumped through a closed plumbing system.

It should help to imagine current as being a continuous flow of particles moving through each component, including the battery/power supply.

Current limiting resistor to protect LED basics diagram by electronzap electronzapdotcom
Current limiting resistor to protect LED basics diagram by electronzap electronzapdotcom

Connecting batteries in parallel adds up their amp hour (Ah)/milliamp hour (mAh). Ah/mAh is how much current they could provide if completely discharged in one hour. If you need a 2Ah battery but only have 1Ah batteries, then you can connect 2 of the 1Ah cells in parallel to create a 2Ah battery. Parallel cells need to be the same voltage when connected. Two 1.5V cells connected in parallel will still power a load at 1.5V but for twice as long or at twice the current if they have the same mAh..  

Eqaul value parallel batteries illustrative diagram by electronzap electronzapdotcom
Eqaul value parallel batteries illustrative diagram by electronzap electronzapdotcom

For basic electronics, you rarely drain a battery in one hour. You can use use a 1Ah (1,000mAh) battery to power a 0.1A circuit for 10 hours instead of providing 1 amp for one hour.

Resistance:

  • Opposition to current from a voltage.
  • Unit: Ohm.
  • Symbol: Ω (Greek letter omega). Very often resistance is in the thousands of ohms (kilohms – kΩ).
  • Water analogy: A small pipe making it harder for water to flow is similar to a high resistance circuit/component. A large pipe where lots of water flows almost freely is similar to highly conductive (low resistance) material/components.

Really cool looking resistor kit linked below. I would buy it if I didn’t have too many resistors already. It has lots of values and packaged really nicely. As an Amazon associate, I earn from qualifying purchases.


Resistor component 1K blue through hole schematics unit symbol diagram by electronzap electronzapdotcom
Resistor component 1K blue through hole schematics unit symbol diagram by electronzap electronzapdotcom

Resistive components are the most basic electrical component. They provide resistance to a voltage and thus limit current and/or divide a voltage.

For each volt across a 1 ohm (1Ω) resistor, 1 amp (1A) of current will flow through it, and it will produce one watt (1W) of power/heat.

Note: You want resistors that are rated to dissipate at least twice the wattage (heat) that it will be calculated to dissipate. Most resistors are rated for 1/4W (0.25W) because most circuits keep them below 1/8W (0.125)

  • 1V/1Ω = 1A of current
  • 1V x 1A = 1W of power (heat generated)

Each volt across a 1,000 ohm (1k) resistor allows 1 milliamp (1mA) of current to flow through it. It also produces 0.001 watt (1mW) of power/heat that it must dissipate.

  • 1V/1000Ω = 0.001A
  • 1V x 0.001A = 0.001W
Equal series resistors split up supply voltage evenly scheatic diagram by electronzap electronzapdotcom
Equal series resistors split up supply voltage evenly scheatic diagram by electronzap electronzapdotcom
  • Series components have the same amount of current flowing through them and they split/divide the supply voltage based on their voltage drop or resistance.

5V across 2 equal value resistors connected in series (see diagram) will mean that there will be an equivalent of twice the resistance of one of them (1,000Ω + 1,000Ω = 2,000Ω). Each of the 2 equal value resistors will have half of the supply voltage across them (divided). The current in amps flowing through the circuit will be the total voltage in volts divided by the total resistance in ohms (ohms law). The heat (power) in watts generated by each resistor will be the voltage (in volts) across it times the current (in amps) flowing through it.

Two equal value parallel resistors will conduct twice the current for a given voltage by providing half the equivalent resistance diagram by Electronzap Electronzapdotcom
Two equal value parallel resistors will conduct twice the current for a given voltage by providing half the equivalent resistance diagram by Electronzap Electronzapdotcom
  • Parallel components have the same voltage across them, and pass a different amount of current through each of them unless they are exactly the same (resistance and/or voltage drop) . The total current passing through them combines and flows through any series circuitry (including connections).
Current through a 1000 ohm resistor is 1mA per volt across the resistor
Current through a 1000 ohm resistor is 1mA per volt across the resistor
  • 5V/1,000Ω = 0.005A (5mA)
  • 0.005A + 0.005A = 0.01A (10mA) total current.

Putting 5 times the voltage across a particular resistance will result in 5 times as much current flowing through it and 25 (5 x 5 = 25) times the power/wattage that needs to be dissipated.

More basic electronics terminology:

Illustrated current through resistors diagram by electronzap electronzapdotcom
Illustrated current through resistors diagram by electronzap electronzapdotcom
      • Conductor: Electrical current flows easily. Low resistance.
      • Insulator: Current is blocked almost completely as long as too high of a voltage isn’t applied.
      • Resistor: A component that is made to provide a specific amount of resistance. Resistance is the opposition to current from a voltage. They mostly come in kits with a wide range of values of resistance and rated for 1/4W. Other wattage resistors are easy to buy if you search for them.
      • Semi conductor: Conductivity depends on certain factors specific to that particular component/material.

        Ohms law voltage current resistance circle graph diagram by electronzap electronzapdotcom
        Ohms law voltage current resistance circle graph diagram by electronzap electronzapdotcom
      • Ohms law: Mathematical formulas used to calculate the relationship between voltage, resistance and current. Formulas: I = V/R     V = I x R     R = V/I
      • Power: Work done (heat and/or light generated, motor speed, etc,): Unit: Watt. Symbol: P Formula: P = VI (electrical power is the voltage across the component(s) times the current through it/them).
      • Ground: There needs to be a difference in voltage between 2 points in order for the possibility of current to flow. Usually the negative side of a supply is declared to be the zero volt reference point ground. The positive side of the power supply is the voltage difference from zero volts. A 1.5V battery positive terminal is +1.5V in relationship to ground, while a 9V battery positive terminal is +9V in relationship to ground. Many circuits have multiple power supplies with different voltages, and all their negative terminals are connected directly together so that they share the same 0 volt reference point voltage (simply called ground).

This site is going to keep the movement of electricity simple.  You need to be familiar with the terms below. Usually you will imagine the movement of electricity as conventional current due to the universally established way we build circuits even to this day. 

  • Conventional current (or just current) : Early scientists could tell that electricity involved something that was either liquid like, being pumped and flowing through entire electrical circuits (current), or shifting from one point to another (static electricity). Not knowing exactly what was going on, it was assumed that electricity flowed from more positive to more negative and thus circuit schematics were designed to look like positive charges were moving from the positive side of the power supply, through the circuit, and back to the negative side of the power supply.
  • Electron flow: Relatively recently it was realized that atoms have negatively charged electrons spinning around positively charges protons. A battery actually moves electrons through it. They flow out of the negative terminal, through any load attached across the battery, and back into the positive side of the battery. Electrons are continuously shifting from one atom to another as long as there is conduction. This is how you will learn about electronics when studying the physics and chemistry of atoms.

 

Simple circuit: Low voltage lightbulb

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

The incandescent light bulb is a nice component to look at first. They are a specially made resistance based component that does something useful (emits light) when enough current is passed through it. You just have to apply the right voltage to it and it lights up. Too low of a voltage and it won’t like up much if at all, and too high of a voltage and the light bulb will burn out early.

Higher voltage incandescent lightbulbs explained:

For informational purposes only. Don’t build higher voltage circuits as they are dangerous. Only use high quality commercially made products as recommended by the manufacturer.

If you are familiar with household incandescent light bulbs…. (they are less common these days as they are being replaced by more energy efficient bulbs.)

      • In the US, household incandescent light bulbs are made to work with 120V alternating current (AC).
      • A 120W incandescent light bulb made for 120VAC will have 120Ω (ohms) of resistance and pass 1A of current while it is on. A couple power formula variations: 120V x 1A = 120W    0r    120W/120V = 1A
      • Alternative types of 120VAC lightbulbs are commonly being used these days. Their wattage rating is usually much lower than incandescent light bulbs even if they emit as much light (because they get less hot), and that is why they are more energy efficient.

Learning electronics topics and pages:

Resistor rectifier diode LED battery single pole single throw and push button switch schematic symbols by electronzap electronzapdotcom
Resistor rectifier diode LED battery single pole single throw and push button switch schematic symbols by electronzap electronzapdotcom

The vast majority of the time, electronic circuits are taught with schematic diagrams using schematic symbols for components. Above is a quick sample of schematic symbols, and below is the typical appearance of some of the most common components.

Common resistor diode capacitor component appearances diagram by electronzap electronzapdotcom electronics
Common resistor diode capacitor component appearances diagram by electronzap electronzapdotcom electronics

Through hole means that there are metal wire leads (pronounced like “leeds”) that can be inserted in holes. Surface mount components have metal areas that can be soldered directly to a surface of something, and are not covered on this site.

More current through a resistor examples:

The current will be the same through the resistor whether it also goes through a meter measuring current, or if it goes directly back to the voltage source (battery in this diagram).

Current through a resistor illustrated and schematic with calculations diagram by electronzap
Current through a resistor illustrated and schematic with calculations diagram by electronzap

9V/1,000Ω = 0.009A (9mA)

Putting a voltage directly across a resistor is the easiest circuit to calculate how much current is flowing by using the Ohm*s law I = V/R .  https://electronzap.com/current-through-a-resistor-learning-electronics-lesson-0001/ .

Current through an LED protected by a resistor from a voltage:

Again, current will be the same whether you connect the battery to resistor, resistor to LED and LED to battery, or if you open up one of those connections and insert a current measuring meter as shown in the diagram.

LED protected by a resistor circuit voltage resistance and current ohms law calculations diagram by electronzap
LED protected by a resistor circuit voltage resistance and current ohms law calculations diagram by electronzap

Diode/LED terminology is covered in more detail further down this page. 

Forward biased (FB) diodes/LEDs drop some voltage from reaching the current setting resistor. Red LEDs drop about 2V while forward biased. Therefore a 9V battery, with 2V dropped from the resistor, will mean there is 7V across the resistor, which sets the current through all the components in the circuit above. 7V/1,000Ω = 0/007A (7mA)

When forward biased (diode wired to conduct easily), the long lead (Anode) of an untrimmed indicator LED needs to head to the positive side of the battery, while the shorter lead (if untrimmed) cathode lead needs to head to the negative side of the battery to light up.

Page covering the diagram above https://electronzap.com/current-through-an-led-circuit-learning-electronics-lesson-0002/ for those who want these topics covered more quickly.

Incandescent light bulbs are relatively rare now as LEDs have mostly taken their place. While studying basic electronics, you will study a lot of circuits with 3 – 5mm indicator LEDs that need to be protected by a resistor. Incandescent light bulbs are resistors that are specially made to get hot enough to emit visible light. Light bulbs don’t need another component to protect them as long as you don’t apply a voltage higher than what they are rated for.

Pay attention to how every component and connection in a lot of simple circuits are connected end to end (series). The same amount of electric current flows has to flow through the entire series circuit at the same time. If you disconnect any part of a series circuit, there will be no current flow.


 


You can’t see voltage or current, so it is important to know how to measure them. Measuring current is done differently than measuring voltage. I show how to measure current further down this list of topics.

Measuring voltages of a simple circuit
Measuring voltages of a simple circuit

Resistance (R) based components limit the current (I) that flows through them based on the voltage (V) across them and their resistance. This is calculated using the Ohms law for current I=V/R .

Resistor component basic properties and schematic symbol diagram by Electronzap Electronzapdotcom
Resistor component basic properties and schematic symbol diagram by Electronzap Electronzapdotcom

Series (connected end to end electrically) components all pass the same amount of current. So if you know the current through any of them, then you know the current through all of them.


LEDs are a type of diode (current flows through one direction but not the other). They light up when current flows through them while forward biased (anode more positive than cathode) , and are therefore a simple way to have a visual for when current is flowing.

Rectifier diode and LED schematic symbols and common appearance with forward biased polarity diagram by electronzap electronzapdotcom
Rectifier diode and LED schematic symbols and common appearance with forward biased polarity diagram by electronzap electronzapdotcom

Make sure to limit current through an LED with a resistor, as is covered in the LED circuit link below. Also, being a diode, if you connect them reverse biased (cathode more positive than anode), then they will block current and not light up.


Lots of beginner circuits include an LED. It is important to know how to protect the LED with a resistor.

Push button switch controlled protected LED circuit schematic diagram by electronzap electronzapdotcom
Push button switch controlled protected LED circuit schematic diagram by electronzap electronzapdotcom
Measuring current with a multimeter schematic diagrams by electronzap
Measuring current with a multimeter schematic diagrams by electronzap

While designing your own circuits, you will need to know how hot resistors (and other components) will get. The power (P), aka. heat generation, of a resistance based component is the voltage (V) across it times the current (I)  flowing through it P =VI  . Most resistors are 1/4Watt (0.25W) but should be kept under 1/8W (0.125W).

1K and 100 ohm resistor current and wattage examples diagram by electronzap electronzapdotcom
1K and 100 ohm resistor current and wattage examples diagram by electronzap electronzapdotcom
Parallel resistors provide more current than one can provide alone schematic and pictorial diagram by electronzap
Parallel resistors provide more current than one can provide alone schematic and pictorial diagram by electronzap
Equal series resistors split up supply voltage evenly scheatic diagram by electronzap electronzapdotcom
Equal series resistors split up supply voltage evenly scheatic diagram by electronzap electronzapdotcom
Half and thirds fixed resistor voltage dividers schematic diagram by electronzap
Half and thirds fixed resistor voltage dividers schematic diagram by electronzap
Through hole resistor component color code diagram image by electronzap and electronzapdotcom
Through hole resistor component color code diagram image by electronzap and electronzapdotcom
Rectifier diode schematic symbol and common black plastic appearance diagram by electronzap electronzapdotcom
Rectifier diode schematic symbol and common black plastic appearance diagram by electronzap electronzapdotcom
Simple trimmer potentiometer trimpot component as voltage divider circuit fragment diagram by electronzap electronzapdotom
Simple trimmer potentiometer trimpot component as voltage divider circuit fragment diagram by electronzap electronzapdotom
Capacitor charge and discharge through resistor and LED circuit schematic diagram by electronzap electronzapdotcom
Capacitor charge and discharge through resistor and LED circuit schematic diagram by electronzap electronzapdotcom
Simple RC time constant charging capacitor at switch release circuit by electronzap electronzapdotcom
Simple RC time constant charging capacitor at switch release circuit by electronzap electronzapdotcom

 

Capacitor constant current voltage ramp diagram by Electronzap Electronzapdotcom
Capacitor constant current voltage ramp diagram by Electronzap Electronzapdotcom
Simple LM334 three terminal adjustable constant current source circuit schematic diagram by electronzap electronzapdotcom
Simple LM334 three terminal adjustable constant current source circuit schematic diagram by electronzap electronzapdotcom

555 timer is an integrated circuit (IC). Being an IC, it has complex circuitry combined in a single package with external pins/terminals to connect to other circuitry. You can easily make all kinds of fun circuits with just a 555 timer and the components covered above, so I think it’s a good component to learn next.

Transistors will probably be the most challenging components to learn. Understanding them will help you understand all of electronics much better, and help you the most in being creative while designing your own circuits.


Nice assortments of semiconductors. Amazon affiliate link ad.

Other topics:

These pages are still being compiled.

Always use datasheets to research components:

When you start using components with part numbers, make sure to do a google search for their datasheet. Information on this site is not guaranteed to be accurate. Always verify any electronics information you get by checking the manufacturer’s datasheet.

Unfortunately datasheet aren’t the easiest documents to understand. I am working on explaining how to make reading them easier.

List of Electronics topics:

There’s an almost endless number of exciting electronics topics that can be studied. Below is many of them. I plan to make a page for as many of them as possible. You should always do google searches of any topics that sound exciting.

 

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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.
      • As an Amazon affiliate, I earn from qualifying purchases.