Diodes are electric components that conduct current very easily in one direction (forward biased), while blocking lot of voltage, and thus current, in the other direction (reverse biased).

In basic electronics, you will mostly learn about.

Rectifier diodes: Made to only let current flow relatively easily in one direction (forward biased), while blocking a lot of voltage, and thus current, in the other direction (reverse biased).

LEDs (light emitting diodes): Emit like while conducting current while forward biased.

Become a Patron!

Basics

Forward biased: Anode (+) while cathode (-)

Reverse biased: Cathode (+) while Anode (-)

Anode is the side without a stripe for most diodes and has a longer lead for indicator LEDs, if the leads haven’t been trimmed.

Cathode side has a band/stripe that is usually gray (for black plastic body) or black (for glass body) diodes. The LED cathode has a shorter lead if untrimmed, and often a flattened edge along the rim.

To donate via Paypal! https://www.paypal.com/paypalme/electronzap

YouTube video covering this topic in much more detail

It is preferred that the blue link is clicked. Video will open in a new tab.

Electronics course 2 rectifier diode and LED forward and reverse biased explained with multimeter



To donate via GoFundMe! https://www.gofundme.com/f/help-fund-learning-electronics-tutorials

Some notes related to the video above.

Forward voltage – the small amount of voltage that a diode drops from the circuit while forward biased (approx. 0.7V for the most common silicon diodes). You need to exceed that voltage in order for the diode to start conducting while forward biased.

Indicator LEDs are usually rated for a maximum of 20mA of current while forward biased. Red LEDs have a forward voltage of about 2V while blue or green LEDs have a forward voltage of about 3V. Typically a resistor is used to limit that current.

Breakdown voltage – How much voltage the diode is rated to block while reverse biased. Exceeding that voltage will allow current to flow, and will likely destroy the diode with the exception of some specially made diodes, such as the zener diode which can safely pass some current while reverse biased.

1N4001 rectifier diodes are commonly included with electronics kits. Being silicon based, they have a forward voltage of about 0.7V. While reverse biased they should be able to block at least 50V. They are rated for a maximum current of 1A while forward biased. As always, check component datasheets for the most accurate specs.

The power supply voltage is split up among series components. Whatever voltage a diode drops is less voltage that is across any other series components.





Nice looking LED kit. Good to have a lot of LEDs because it’s relatively easy to damage them, or to want to use a lot of them in various projects.

Other topics:



One of my favorite portable power banks, this one has a better display than my version.

Home page