Snail mail notification system

[Mime] lives on one of the upper levels of an apartment complex. The mailboxes, being located at the ground floor can be somewhat inconvenient to check regularly. [Mime] decided to rig up a device to let him know when his mailbox had been accessed. He started with a wireless doorbell, thinking he could use the door side button inside his mailbox as a trigger with only some slight modification. On the receiver side, he wanted an LED to flash, letting him know that it was time to check his mail. One simple circuit and a self blinking LED later and the whole setup was finished. Great job [Mime]

Replacing the driver board in an old-school door chime

[Dan Kouba's] parents replaced their doorbell button with one that lights up and found that the chime wouldn’t stop sounding after the button was pushed. These lighted buttons use an incandescent bulb in parallel with the button (a piece of hardware we’ve hacked in the past). It draws a small amount of current which isn’t enough to trigger the chime, but it is just enough that the chime unit reacts as if the button press never stopped. His parents asked what he could do about this and after some investigation he build a replacement board for the chime unit based around an ATtiny26L. The board monitors the voltage drop across a resistor in the doorbell circuit. When the comparator on the AVR detects a rise in the voltage drop across the resistor it rings the chimes, actuating the solenoids with a set of PNP transistors. [Dan] sent us all of the details which you can check out after the break.

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Doorbell combo lock can open your garage door

Sometimes I get enough away from writing about other people’s accomplishments long enough to actually do my own hacks. Most recently I developed a combination lock that opens the garage door. The idea isn’t original, it is based on [Alan Parekh's] button code project, but I did develop my own hardware and software. A four digit code is entered by pressing the button a number of times for the first digit, and waiting for a flash of an LED inside before moving on to the next digit. If the correct code is entered the door opens.

My version centers around an ATtiny13. I originally downloaded [Alan's] code in hopes that I could port the PIC firmware over pretty easily. Unfortunately it was written in BASIC so I just took what I knew about the interface and wrote my own program. I developed on an ATmega168 so that I would have no trouble running out of programming space, and was able to optimize my code down to 964 bytes to fit on the tiny13.

The hardware is quite simple. I purchased a lighted doorbell from Home Depot and swapped out the light bulb for an LED. I choose this because the doorbell mounts in a 5/8″ hole in the trim of the garage door and is easily overlooked. I’m quite happy with the results, and if you want to play around with the idea, you can easily build the circuit on a breadboard and use another LED for the load rather than including a relay. Hit the link at the top of this post for the schematic, code, and build images.

Lunkenheimer steam whistle, doorbell

We’re going to straight out agree with [Pete] on how surprisingly quiet doorbells are now a days, and if we had it our way we would put his Lunkenheimer train whistle doorbell in every home*. The setup he uses is surprisingly simple, opting for a pre-built wireless doorbell that signals a microcontroller which in turn drives a relay and solenoid. While he does include a video, we felt it didn’t quite show the intensity of these whistles.

*HaD is not responsible for hearing loss and subsequent melted brains.

Antique phone doorbell

doorbell

[Bryan] sent in this cool doorbell he made out of an antique phone. After seeing similar phones for $150 to $399, he picked one up on ebay for $10. After some cleaning and polishing, it was looking fantastic, but fairly useless. At this point, he broke it open and started hacking to turn it into a wireless doorbell. He picked up a cheap wireless doorbell and proceeded to gut it. The transmitter side got an aesthetic overhaul, a big fancy button and nice LED in a 50′s style  were added. The receiver side got hacked up as well. It was incapable of pushing the required voltage to ring the phone’s bell, so he had to do some searching for a better circuit. Since his knowledge of electronics was limited, he was looking for something that could be plugged in and work without much modification. Eventually, he found the Silvercom AG1170-s5. At $7, he swiped it up quick. It may be a bit of overkill, but he’s using an arduino to trigger the whole thing when it receives the signal. You can download the Arduino sketch on the site.