This contest has ended and the winners have been announced. Thank you to everyone who joined in on the challenge fun!

Be sure to check out all the other amazing projects that joined this challenge.

Introduction:

One second. Sixty of them in a minute, 31 million in a year, and maybe two-and-a-half billion of them in your lifetime. Turn the second over on its head and you’ve got the pace of a relaxed human heartbeat. 

For this challenge, we want you to design a device where something happens once per second. How accurately you pace the beat, how absurd the display, or how diabolical the mechanism behind it all, we want to see it. Let your creativity run wild, as long as something happens at that most fundamental of all frequencies.

The top three entrants will receive a $150 shopping spree courtesy of DigiKey, this challenge's sponsor!

Honorable Mention Categories:

• Timelords: How precisely can you get that heartbeat? This category is for those who prefer to see a lot of zeroes after the decimal point. 
• Ridiculous: This category is for the least likely thing to do once per second. Accuracy is great, but absurdity is king here. Have Rube Goldberg dreams? Now you get to live them out.
• Clockwork: It’s hard to mention time without thinking of timepieces. This category is for the clockmakers among you. If your clock ticks at a rate of one hertz, and you’re willing to show us the mechanism, you’re in.
• Could Have Used a 555: We knew you were going to say it anyway, so we made it an honorable mention category. If your One Hertz project gets its timing from the venerable triple-five, it belongs here.

How to Enter

Document your project on Hackaday.io. Share images or videos of your project and tell the story of how you designed and built it in the description of your project.

Once you have published your project, look in the left sidebar for the "Submit project to..." menu to enter it in the One Hertz Challenge:

Rules:

• All entries must do something once per second: exactly what, how precisely, and by what means – that’s the game.
• We want to learn from you. Document your project as well as you can so that we can follow along. Claims of insane accuracy will need solid backup, but that’s half the fun.

• All entrants must agree to have the design published on Hackaday.

• Employees and contractors of DigiKey, Supply Frame, Siemens, Arduino, and their immediate family members are ineligible to win, but are still encouraged to enter.
• Rules and categories are subject to change, and judges' decisions are final

Important Reminder: Previously created projects may be submitted to the contest, but they must be updated within the timeframe of this contest. Previously created projects submitted with no updates will be disqualified.

Deadline to submit your project: Tuesday, August 19, 2025 09:00 am Pacific 

To get started, start a project on hackaday.io and upload your project.

Examples

Need some inspiration? Here are some projects to check out that should get your ideas flowing:

• Certainly one of the most absurd one-hertz projects we’ve ever seen was [Sprite_tm]’s entry into 2017’s Flashing Light prize where he pinged servers all around the world to blink a light at about one hertz. 
• Need to brush up on your 555? Check out our “Brief History” of this little timer. 
• Want a head start on your accuracy project? Consider GPS, and build from there. Or maybe rubidium is more your style.
• We don’t need to tell you that Hackaday likes creative clocks. But we have a special place in our hearts for [ekaggrat singh kalsi]’s lovely mechanical displays. Unfortunately, none of them display the seconds! Will you rise to the challenge?

A big thanks to Joe Kim for the amazing art!

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