flasher

8 Articles

2025 One Hertz Challenge: Using Industrial Relays To Make A Flasher

August 10, 2025 by 8 Comments

These days, if you want to flash some LEDs, you’d probably grab a microcontroller. Maybe you’d go a little more old-school, and grab a 555. However, [Jacob] is even more hardcore than that, as evidenced by this chunky electromechanical flasher build.

[Jacob] goes into great detail on his ancillary write-up, describing how the simple building blocks used by industrial control engineers can be used to make a flasher circuit that cycles once per second. Basically, two relays are paired with two 0.5-second delay timers. The two relays tag each other on and off on delay as their timers start and expire, with the lamp turned on and off in turn.

We’ve had lots of other great entries to our One Hertz Challenge, too — from clocks to not-clocks. There’s still time to get an entry in — the deadline for submission is Tuesday, August 19 at 9:00AM Pacific time. Good luck out there!

2025 Hackaday One Hertz Challenge

2025 One Hertz Challenge: Blinking An LED The Very Old Fashioned Way

August 5, 2025 by 10 Comments

Making an LED blink is usually achieved by interrupting its power supply, This can be achieved through any number of oscillator circuits, or even by means of a mechanical system and a switch. For the 2025 One Hertz Challenge though, [jeremy.geppert] has eschewed such means. Instead his LED is always on, and is made to flash by interrupting its light beam with a gap once a second.

This mechanical solution is achieved via a disk with a hole in it, rotating once a second. This is driven from a gear mounted on a 4.8 RPM geared synchronous motor, and the hack lies in getting those gears right. They’re laser cut from ply, from an SVG generated using an online gear designer. The large gear sits on the motor and the small gear on the back of the disk, which is mounted on a bearing. When powered up it spins at 60 RPM, and the LED flashes thus once a second.

We like this entry for its lateral thinking simplicity. The awesome 2025 One Hertz Challenge is still ongoing, so there is still plenty of time for you to join the fun!

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Lamp Flashing Module Is Perfect For Automotive Use

October 1, 2022 by 17 Comments

Modern cars tend to have quite advanced lighting systems, all integrated under the control of the car’s computer. Back in the day, though, things like brake lights and indicators were all done with analog electronics. If your classic car needs a good old-fashioned flasher module, you might find this build from [DIY Guy Chris] useful.

It’s an all-analog build, with no need for microcontrollers or other advanced modern contrivances. Instead, a little bipolar PNP transistor and a beefier NPN MOSFET as an oscillator, charging and discharging a capacitor to create the desired flashing behavior. Changing the size of the main capacitor changes the flash rate. The MOSFET is chosen as running 12 volt bulbs requires a decent amount of current. The design as drawn is intended to run up to eight typical automotive bulbs, such as you might find in indicator lamps. However, [Chris] demonstrates the circuit with just four.

Flasher circuits were in regular use well into the 1990s. The original Mazda Miata has a very similar circuit tucked up under the dashboard to run the turn signals. These circuits can be hard to find for old cars, so building your own may be a useful workaround if you’re finding parts hard to come by. Video after the break.

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ESP32 Turned Handy SWD Flasher For NRF52 Chips

July 1, 2021 by 9 Comments

Got an nRF52 or nRF51 device you need to flash? Got an ESP32 laying around collecting dust? If so, then firmware hacking extraordinaire [Aaron Christophel] has the open source code you need. His new project allows the affordable WiFi-enabled microcontroller to read and write to the internal flash of Nordic nRF52 series chips via their SWD interface. As long as you’ve got some jumper wires and a web browser, you’re good to go.