Electronics learning for hobbyists and students

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

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Notice: I am starting over building this site. The old pages have been deleted so that I can focus on making better material.

Basic circuits

Keep in mind that incandescent light bulbs are really rare now (replaced with LEDs). They are however a simple component to understand.

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

Electronics involves combining components together to form circuits that do something useful. All circuits generally contain at least…

  • Power source – Provides voltage and current to a load.
  • Load – Does something useful with the voltage and current from the power source.
  • Connectors – Provide an electrically conductive path from the power supply, to the load, and back to the power supply.
  • Conductor – Passes current easily.
  • Insulator – Doesn’t pass current easily. Typically used to keep conductors separated.
Imagining current flow illustartions for push button switch a resistor components diagram by electronzap
Imagining current flow illustartions for push button switch a resistor components diagram by electronzap
Incandescent light bulb schematic symbols and simple circuit illustration diagram by electronzap
Incandescent light bulb schematic symbols and simple circuit illustration diagram by electronzap

When current flows through a light bulb, it’s filament heats up and it emits light.

More voltage means more current, and thus more heat for a resistive component such as a light bulb. Therefore don’t exceed the light bulb’s rated voltage.

Schematic symbol for a battery (shown later) is alternating short and long lines with gaps between them. Typically the recommended voltage is written next to the symbol.

Any direct current (DC) voltage source can be used to provide power to a DC load regardless of the power source symbol shown in the schematic. Just make sure it is the proper voltage.

Basic circuits using light bulb and LEDs explained for electronzap learning electronics lesson 0001

LED protected by a resistor:

LED protected by a resistor pictorial and schematic diagram
LED protected by a resistor pictorial and schematic diagram

Much more common these days is the LED protected from a power source with a resistor circuit.

  • Protective resistor must have high enough resistance to limit current below 20mA for most LEDs. It’s resistance must also be high enough that it doesn’t get too hot (wattage) for the voltage being applied.

Most resistors are rated to dissipate a maximum of 1/4W (0.25W) of power. It is still recommended to stay below 1/8W (0.125W).

1,000 ohms (1K) is good for protecting an LED from 12V, 470Ω is good for protecting an LED from 9V and 220Ω is good for protecting an LED from 5V. Higher resistance can be used. The LED just won’t be as bright.

Battery basics:

Batteries are a cheaper voltage source than a plug in power supply, but they need to be replaced often, or recharged if rechargeable.

Battery cell voltage basics for alkaline and rechargeable lithium ion chemistries diagram by electronzap
Battery cell voltage basics for alkaline and rechargeable lithium ion chemistries diagram by electronzap

A cell combines the chemistry needed to provide a voltage. The nominal voltage will depend on the chemistry involved.

  • Alkaline has a nominal cell voltage of 1.5V. The actual voltage ends up being 1.6V while brand new (they usually aren’t recharged), and somewhere close to 1V when fully discharged.
  • Lithium ion (li ion) cells usually have a nominal voltage of 3.6V, which ends up being 4.2V when fully charged and 3V when fully discharged. Stay within that voltage range to prevent dangerous damage.
  • Series cells: Connecting cells end to end (positive of one cell to negative of another cell) adds up the voltage of each cell when taken from the 2 far ends.
  • Parallel cells: Connecting the positive end of each cell to each other, as well as connecting the negatives ends to each other, provides the same voltage as one cell, but adds up how much total current can be provided to a load. Make sure Batteries have the same voltage (no more than about 0.1V difference) before connecting in parallel.

Battery holders that connect the cells in series or parallel for you are common.

A 9V alkaline battery has the chemistry of six 1.5V cells contained in one package.

“9 volt” lithium ion rechargeable batteries can only be charged to 8.4V because they are made up of two 3.6V cells (4.2V cells when fully charged). I prefer to call them almost 9V batteries.

Always use a proper battery charger for the chemistry involved, unless you learned how to charge them yourself.

Diode/LED polarity

Diode LED schematic symbols and forward reverse biased polarity basics illustrated by electronzap
Diode LED schematic symbols and forward reverse biased polarity basics illustrated by electronzap

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  • LED must be inserted in the right direction to light up (forward biased). That is when the Anode (longer lead) is more positive, and the Cathode (shorter lead) is more negative. That assumes that the Anode lead has not been trimmed. Leads (pronounced as “leeds”) are the metal wires coming out of through hole components. Many LEDs also have a flat edge on the cathode side.

Other types of diodes have a band painted on the cathode side of the component.

  • Schematic diagrams are drawings of circuits where symbols are used to identify components and their connections, instead of using drawings or pictures of actual components.

Using Ohms law for calculating current and multimeter measurements learning electronics lesson 0003



I really like the kit above for learning basic electronics and Arduino. This is an affiliate link ad, so I earn from qualifying purchases, which helps me devote time to improving this site.

(protective) resistor setting current

Resistors set current through them (and series components) based on the voltage across them and their resistance.  Current (in Amps – I) through a resistance is the voltage (in volts – V) across the resistance divided by the resistance (in ohms – Ω). That is the Ohms law formula I = V/R .



Really nice looking resistor kit for those beginning studying electronics. Affiliate link ad.

Current through a resistor illustrated and schematic with calculations diagram by electronzap
Current through a resistor illustrated and schematic with calculations diagram by electronzap
  • 1V/1,000Ω = 0.001A (1mA – one milliamp)
  • 10V/1,000Ω = 0.01A (10mA – ten milliamps)

A resistor heats up when it passes current. They are rated for wattage instead of current. Larger resistors can dissipate heat better, and thus have a higher wattage rating than smaller resistors. W=IV

  • 1V/0.001A = 0.001W
  • 10V/0.01A = 0.1W

When you buy resistors, they generally all come in the same size (wattage) even though they have different resistance values.

Most commonly sold are 1/4 watt resistors. Therefore it is generally assumed that you are using 1/4W resistors unless another wattage resistor is indicated.

Wattage and power calculations for resistive components learning electronics lesson 0004


Power supply used in my videos. Affiliate link ad.


Nice assortments of semiconductors. Amazon affiliate link ad.

 

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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.
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