Electronic components

Circuits are made up of electronic components. At first, there may seem to be an overwhelming number of components to learn about, but there’s actually only a handful of simple ones that are in almost every circuit. The rest can be quickly studied as you come across them. Here’s some of the assorted component kits that I have and like.

Information not guaranteed to be accurate. Always consult with the manufacturer datasheet of any part you use.

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Basic components

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

Resistors are the most common component.

  • Limits current (I) from a voltage. I = V/R
  • Divides voltage based on it’s percentage of the total series resistance after semiconductor voltage drops are taken into account.
  • Gets hot easily. Make sure the resistors you use are rated for twice the wattage (P) that they are expected to continuously have to dissipate. P = VI
  • Through hole resistors use colored stripes/band to indicate their resistance value and tolerance (percent they may differ from their rated value.
  • Ω (omega) symbol used to indicate the value of resistance.
  • Resistor component

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
  • LEDs (most common type of diode)

The LED is a really nice component for beginning electronics because they light up.

  • Diode: LED stands for light emitting diode. It conducts easily when a relatively low voltage is applied in one direction (forward biased) and blocks current when voltage (within limits) is applied in the wrong direction (reverse biased). It’s not a replacement for other types of diodes though.
  • Forward biased: LEDs start conducting and lighting up when the Anode is more positive than the Cathode by approx. 1.5-3V depending on the particular LED.
  • Reverse biased: LEDs don’t conduct current when the Cathode is more positive than the Anode, up to it’s breakdown voltage (which might only be about 12V). Exceeding the breakdown voltage will burn out the LED.
  • Current limit: The way to protect an LED is to limit it’s current. Usually a resistor is used, that is high enough value to limit the current below 20mA for most LEDs used in basic electronics. The supply voltage, minus the LED forward voltage drop will be across the resistor, which then sets the voltage based on it’s resistance.

Brief switch controlled indicator LED circuit

Brief polarity indicator LEDs circuit


Normally open (off) push button switch illustrative diagram by electronzap electronzapdotcom
Normally open (off) push button switch illustrative diagram by electronzap electronzapdotcom
  • Switch (normally open push button is common)

Switches make and break electrical connections in a number of ways.

The push button switch has a button, that when pressed, usually closes (turns on) the circuit and allows current to flow.

Those normally open (NO) push button switches are commonly included in electronics kits and I use them often in my videos. This site doesn’t really look at any other switch types other than relays.


Capacitor component common appearances schematic symbols and basic uses diagram by electronzap electronzapdotcom
Capacitor component common appearances schematic symbols and basic uses diagram by electronzap electronzapdotcom
  • Capacitors

Capacitors store energy through an imbalance of charges on it’s plates that is provided by a voltage source. They can briefly power a load from that stored charge.

  • Polarized: Can only be charged in one direction. Usually the negative side is indicated, and it needs to be connected to the more negative side of the power supply while being charged. Mostly larger value capacitors.
  • Non polarized: Doesn’t matter which side is more positive or negative than the other.
  • Farad (F): The amount of charge it takes to change the voltage of the capacitor. 1F takes one coulomb of charge to change the capacitor voltage by 1V.
  • RC time constant (τ): Using a resistor to limit current charging/discharging a capacitor results in a very rapid voltage change at first, and a slow voltage change towards the final voltage. Multiplying the capacitance (C) in farads by the resistance (R) in ohms gives the RC time constant. τ = RC . It takes 5 time constants to fully charge or discharge a capacitor through a resistor.
  • Voltage ramp: A steady current results in a steady voltage change, resembling a ramp when graphed.
  • Timing. Since capacitor voltage change takes a calculable amount of time (unless shorted), you can make circuits, or use manufactured integrated circuits, that respond to that amount of time.

Brief capacitor charge and discharge through LEDs circuit

Brief capacitor charging RC time constant demonstration circuit

Brief capacitor discharge RC time constant circuit

Brief charging capacitor voltage ramp circuit using LM334 current source

Brief discharging capacitor voltage ramp using LM334 current source


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
  • Diodes (rectifier)

Rectifier diodes are made especially to conduct current in one direction only.

  • Forward biased: Rectifier diodes conduct current fully once it’s anode is more positive than it’s cathode by it’s forward voltage (about 0.7V for silicon diodes). That voltage is lost to/dropped from the rest of the series circuitry.
  • Reverse biased: The rectifier diode will block a certain amount of voltage while reverse biased, depending it’s part number. About 50V for the commonly used 1N4001. Exceeding that will lead to breakdown, and likely a destroyed  rectifier diode.
  • Maximum current. Depends on the part number. 1N4001 has a rated maximum forward current of about 1A.

  • Inductors

2N3904 NPN BJT pin layout schematic symbol and current paths diagram by electronzap electronzapdotcom
2N3904 NPN BJT pin layout schematic symbol and current paths diagram by electronzap electronzapdotcom
  • Transistors (bipolar junction transistors)

Transistors are 3 terminal devices. How well current flows through 2 of the terminals depends on the voltage and/or current at the third terminal.

Bipolar junction transistors (BJTs) are the most commonly used transistors for hobbyists/beginner learning electronics. NPN is more common than PNP.

Other part numbers have other pin layouts. So far though, I found that if it begins with 2N and is a BJT, that it has the pin layout shown.

NPN BJTs:

  • Collector is wired more positive than emitter. Their conduction is normally off.
  • Base getting more positive than emitter by about 0.6V allows base to emitter current to flow.
  • Base to emitter (B-E) current allows a multiple amount of current to flow from collector to emitter. The exact multiple amount is called gain/Beta/Hfe, but that amount is unpredictable. It is mostly important that the particular transistor being used have more gain than you need.

Quick NPN BJT switch circuit – Bipolar Junction Transistor

Brief NPN BJT timed off fade circuit- RC time constant

Brief NPN BJT current source controlled by trimpot voltage divider circuit

Brief NPN BJT emitter follower set by trimpot using 2N3904 bipolar junction transistor

2N3906 pin layout and voltage direction diagram by electronzap electronzapdotcom
2N3906 pin layout and voltage direction diagram by electronzap electronzapdotcom

PNP BJTs:

  • Collector more negative than emitter. Normally not conductive.
  • Base getting more negative than emitter by about 0.6V allows current conduction from emitter to base.
  • E-B current conduction allows a multiple amount of + to – current to flow from emitter to collector depending on it’s gain. Again, use a transistor that will definitely have more gain than you will need.

2N3906 PNP bipolar junction transistor BJT schematic symbol and pin layout diagram by electronzap electronzapdotcom
2N3906 PNP bipolar junction transistor BJT schematic symbol and pin layout diagram by electronzap electronzapdotcom

Brief PNP BJT switch circuit – Bipolar Junction Transistor

Brief PNP BJT timed fade off switch – 2N3906 bipolar junction transistor

Brief PNP BJT current source set by trimpot circuit – 2N3906 bipolar junction transistor

Brief PNP BJT emitter follower common collector – 2N3906 bipolar junction transistor

Integrated circuits

The minimum chemistry needed to make components barely takes up any space. Therefore they are usually combined into a single component called an integrated circuit (IC). The through hole versions of ICs have pin like terminals for making connections to other components needed to interact with it, and the power supply.

  • 555 timer
  • Single supply op amp – LM358
  • Dual supply op amp – (LM/µA)741
  • 7400 and 4000 series ICs- Many different circuit options depending on the last 2 or 3 part numbers following the 74xx… or 40xx…. . And also, the letters used (HC and LS are most commonly known).

variations/other components

Modules

These are circuit boards that typically have integrated circuits and/or larger components, and the needed supporting components already connected together. They are commonly used with arduino or other boards that can read info from them, tell them to turn on/off, and/or other interactions. You need to do some programming to prepare the board to interact with the particular module, but arduino (I don’t know about others) has tons of sample programs available that might do all you need, or that can modified as needed.

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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.