See Them Knocking with a Doorbell Alert
Imagine you’re in the middle of an intense workout, running through a virtual forest on your treadmill, completely lost in the rhythm of your music. Suddenly, the doorbell rings—but with your headphones on and the noise of the treadmill drowning everything out, you don’t even realize it until later when you find a “we’ll try again” notice for your missed delivery.
That’s where Antonio’s clever DIY solution comes in. Using a pair of 555 timers, he created a system that listens for the doorbell and activates a giant 20 mm red LED to flash and alert him. One 555 is set up in astable mode to control the flashing rate, while the other is in monostable mode to manage how long the light stays on. Power for this setup comes from the 9V doorbell line, conveniently wired through an existing Ethernet jack.
Now, every time the doorbell rings, Antonio has 60 seconds of bright, flashing red light to stop the treadmill and make it to the door. When he’s not exercising, he can conserve power using a simple on/off switch, making this an efficient and practical solution to an otherwise common problem.

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