• Skip to main content
  • Skip to primary sidebar

Homemade Circuit Projects

Need circuit help? Post them in the comments! I've answered over 50,000!

Blog | Categories | About | Contact | Calculators-online
You are here: Home / Electronics Theory / Diodes: Working, How to Use, Applications

Diodes: Working, How to Use, Applications

Last Updated on January 3, 2024 by Swagatam 2 Comments

It's John Ambrose Fleming (1849-1945), a British engineer, who invented the first diode in 1904, in the form of an electron tube. Later, with the development of semiconductor technology, the diode became a dipole consisting of two substrates: one, rich in free electrons, and of type N, the other deficient in electrons, and of type P.

Table of Contents
  • General Working
  • Direct current behavior - Single diode
  • Diodes connected in series
  • Diodes connected in parallel

The diode only allows current to flow in the P-N direction. The doped P part is called the anode, while the cathode corresponds to the doped N part.

General Working

When inserted into a circuit, a diode is in a blocking state if the cathode potential is higher than that of the anode.

However, if the potential is reversed, it can be observed that current only begins to flow if the potential value is greater than a threshold voltage. For typical silicon diodes, this threshold voltage is around 0.6 volts. It is 0.3 volts for germanium diodes and can reach up to 3 volts for light-emitting diodes (LEDs).

This voltage remains almost constant for all current levels crossing the junction, as long as they do not exceed the nominal value for which the diode was designed.

Related Post:
  • What is Hysteresis in Electronic Circuits

By hydraulic analogy as shown below , the operation of a diode can be compared to a pipeline in which a ball check valve only allows a flow of liquid in the direction where pressure pushes the ball down by compressing a spring.

warning message: electricity is dangerous, proceed with caution

The "threshold pressure" is the pressure required to neutralize the action of the spring pushing the ball onto its seat.

Direct current behavior - Single diode

Consider a direct current source with a potential of U supplying a circuit consisting of a resistance R in series with a diode D. For a current to be established, it is necessary to satisfy the condition:

U > UD

A potential UD is measured across the diode. In the case of a silicon diode, UD = 0.6 V.

Related Post:
  • Exploring Current Mirror Circuits with Practical Designs

The potential difference across R is given by UR = U - 0.6 V, and the current I is determined by applying Ohm's law: I = UR / R.

The diode D dissipates power P = 0.6 x I.

If the value of I exceeds the nominal limit of the diode, the temperature of the diode increases significantly, which can lead to its destruction.

Diodes connected in series

The establishment of a current is subject to the condition U > 1.8 V (since 3 silicon diodes are connected in series, each having a threshold voltage of 0.6 V). Indeed, the threshold voltages are added in this type of connection.

As explained previously, the value of the potential difference across R can be calculated by applying the relationship:

Related Post:
  • How Thyristors (SCR) Work – Tutorial

UR = U - 1.8 V

Similarly, for the current I = UR / R, and the total power P dissipated in the three diodes is 1.8 x I. If the diodes have the same characteristics, the power dissipated by each diode will be one third of the total power.

Connecting diodes in series allows for a fixed potential, which is a multiple of the threshold potential of the diodes, to be obtained. This potential can be used as a reference in certain applications where the current is variable.

Diodes connected in parallel

In practice, a parallel connection of diodes is not useful. Simply because, the current I will flow through the diode with the lowest threshold potential (forward voltage drop). This will result in almost no current flowing in the other parallel diodes.

This implies that one of the diodes would be conducting and allowing the entire current to flow through it, while the other diodes would remain turned OFF. It should be noted that even identical diodes have different manufacturing tolerances, so there will always be differences in the threshold potential.

Related Post:
  • Understanding SG3525 IC Pinouts

You'll also like:

  • 1.  Simple Buck-Boost Converter Circuits Explained
  • 2.  How to Compare IGBTs with MOSFETs
  • 3.  How to Connect Resistors in Series and Parallel
  • 4.  What is Constant Current Source – Facts Explained
  • 5.  How to Make Logic Gates using Transistors
  • 6.  How to Configure Resistors, Capacitors and Transistors in Electronic Circuits

Filed Under: Electronics Theory Tagged With: Applications, Diodes, Working

About Swagatam

I am an electronics engineer and doing practical hands-on work from more than 15 years now. Building real circuits, testing them and also making PCB layouts by myself. I really love doing all these things like inventing something new, designing electronics and also helping other people like hobby guys who want to make their own cool circuits at home.

And that is the main reason why I started this website homemade-circuits.com, to share different types of circuit ideas..

If you are having any kind of doubt or question related to circuits then just write down your question in the comment box below, I am like always checking, so I guarantee I will reply you for sure!

Previous Post: « IC 7805 Switching Regulator Circuit
Next Post: BC636 Transistor Datasheet [45 V 1 Amp PNP Transistor] »

Reader Interactions

Comments

  1. suat kaleli says

    June 2, 2023 at 11:57 am

    Hi Swagatam;

    I think for instant 1n4001 allows the current up to 1 ampere. However, if they were used 4 pcs of them in a rectifier bridge so that means this rectifier capacity is 2 amperes or what?
    My other question is that it is possible to use flyback or shotky diodes to make bridge rectifier?

    Best Wishes

    Reply
    • Swagatam says

      June 2, 2023 at 12:07 pm

      Hi Suat,
      1 amp is the maximum current handing capacity for 1N4001—1N4007 diodes, but they can start heating up even at 400 mA.
      The maximum current handling capacity of a bridge rectifier using 1N4001–1N4007 diodes will be 1 amp only, not 2 amps.

      Yes, shottky diodes can be used for making bridge rectifiers.

      Reply

Need Help? Please Leave a Comment! We value your input—Kindly keep it relevant to the above topic! Cancel reply

Your email address will not be published. Required fields are marked *

Primary Sidebar

circuit simulator image

Subscribe to get New Circuits in your Email



Categories

  • Arduino Projects (89)
  • Audio and Amplifier Projects (132)
  • Automation Projects (17)
  • Automobile Electronics (101)
  • Battery Charger Circuits (83)
  • Datasheets and Components (106)
  • Electronics Theory (143)
  • Free Energy (37)
  • Games and Sports Projects (11)
  • Grid and 3-Phase (19)
  • Health related Projects (25)
  • Home Electrical Circuits (12)
  • Indicator Circuits (14)
  • Inverter Circuits (88)
  • Lamps and Lights (142)
  • Meters and Testers (69)
  • Mini Projects (46)
  • Motor Controller (64)
  • Oscillator Circuits (28)
  • Pets and Pests (15)
  • Power Supply Circuits (108)
  • Remote Control Circuits (50)
  • Security and Alarm (64)
  • Sensors and Detectors (102)
  • Solar Controller Circuits (59)
  • Temperature Controllers (42)
  • Timer and Delay Relay (49)
  • Transmitter Circuits (29)
  • Voltage Control and Protection (40)
  • Water Controller (36)



Other Links

  • Privacy Policy
  • Cookie Policy
  • Disclaimer
  • Copyright
  • Videos
  • Sitemap

People also Search

555 Circuits | 741 Circuits | LM324 Circuits | LM338 Circuits | 4017 Circuits | Ultrasonic Projects | SMPS Projects | Christmas Projects | MOSFETs | Radio Circuits | Laser Circuits | PIR Projects |



Social Profiles

  • Twitter
  • YouTube
  • Instagram
  • Pinterest
  • My Facebook-Page
  • Quora
  • Stack Exchange
  • Linkedin


  • Recent Comments

    • Swagatam on 3 High Power SG3525 Pure Sine wave Inverter Circuits
    • Swagatam on Crystal Radio Sets with Amplifier Circuit
    • Alexander on 3 High Power SG3525 Pure Sine wave Inverter Circuits
    • Swagatam on 5V, 12V Buck Converter Circuit SMPS 220V
    • Swagatam on Crystal Radio Sets with Amplifier Circuit

    © 2025 · Swagatam Innovations