Flyback Diode - Inductive Kickback and Supression

in electronics •  10 months ago

Flyback Diodes

I posted this on YT awhile back. There are some students talking in the background, but once I get going the audios is better.

This videos shows the schematic and demonstrates the operation of a flyback diode with an oscilloscope. The flyback diode will suppress the inductive kickback from the relay when switched into the circuit.


A function generator drives a NPN bipolar junction transistor (BJT) and the frequency is increased to help trigger the scope and demonstrate the application. When the switch for the fly-back diode is open the relay can be heard with the reverse magnetic field applied from the inductance.

When the switch is closed, the flyback diode is in the circuit and the inductor can discharge through the diode with around 700mV max, while without the diode this relay coil peaked at over 100V. Keep in mind the peak occurs when turning the relay off.

K is the reference designater for Relay, and Q is for transistor. This transistor is a switch that is saturated to sink current to the relay coil to energize relay. In other words the NPN 2N3904 provides the ground (current sink). The relay coil is connected to +12V. When energized the coil creates an electromagnetic field to toggle the contacts and control the LEDs.

When energized the relay contacts toggle and the NO (normality open) contacts close, and the NC (normally closed) contacts open. LEDs are used to demonstrate the NO and NC relay contacts.

Authors get paid when people like you upvote their post.
If you enjoyed what you read here, create your account today and start earning FREE STEEM!
Sort Order:  

This post has a real potential to earn on steemit under the education tag and with a little bit of work and citations could get votes from steemstem. I realize you are a little newer so you may not know much but here are some things that might peak your interest: Steemstem Helpful Guidelines and Being A Steemstem Member

This post doesn't quite meet qualifications for being crated though but it definitely is a good post. Before you ask, there is no requirement fee to becoming a person curated by steemstem, just write any STEM related post and we will reward you, assuming you have the minimum requirements (such as citing sources, credit images, and continue with this quality)

We thank @nitesh9 and @rocking-dave for the creation and rights to use the steemSTEM images and gifs presented throughout this post


Thank you for the kind words. After looking at your guidelines, I will make the next one better. This is a re-post of work I did a while back. While the content is all mine, it is not polished. --Thanks again for the feedback!


No worries, I looked at your post and thought it was good just it doesn't quite meet guidelines, I hope to see posts from you in the future!