Never Miss A Doorbell With This Notifier

[PatH] tells us that he tragically missed a craft beer delivery to his home, and vowed never to let this happen again. His problem was that he’d missed the doorbell, resulting in one of those annoying notes from the delivery guy. His solution? An ESP8266-driven doorbell detector, that both sends him an SMS and records each doorbell press to a Google Sheet.

The doorbell detection is surprising but simple and non-intrusive, instead of running a GPIO line through some kind of interface to the button itself he’s added a reed switch to his ESP8266 board and used that to detect the magnetic field of the bell solenoids. It’s a convenient method, but one that only works with an old-style bell.

When the bell rings the magnetic field triggers the reed switch, and in turn the sketch running on the ESP calls out to IFTTT which triggers both an SMS and a write to a Google Sheets document that records each doorbell activation.

The ESP8266 seems to be a popular choice with doorbell automatprs probably because of its built-in networking and low price, but it’s not the only option. This optocoupler-sensed effort for example uses a Particle Xenon.

A Battery Sipping Cellular Mailbox Notifier

Like many of us, [Zak Kemble] has an indeterminate number of tiny packages coming his way from all over the globe at any given time. Unfortunately, the somewhat unpredictable nature of the postal service where he lives meant he found himself making a lot of wasted trips out to the mailbox to see if any overseas treasures had arrived for him. To solve the problem, he decided to build an Internet-connected mailbox notification system that could work within some fairly specific parameters.

For one thing, the mailbox is too distant to connect directly to it over WiFi. [Zak] mentions that 433 MHz might have been an option, but he decided to skip that entirely and just connect it to the cellular network with an A9G GPRS/GSM module from A.I. Thinker. This device actually has its own SDK that allows you to create a custom firmware for it, but unfortunately the high energy consumption of the radio meant it would chew through batteries too quickly unless it had a little extra help.

Not wanting to have to change the batteries every couple months, [Zak] added a ATtiny402 to handle the notifier’s power management needs. By using a P-MOSFET to completely cut power to the A9G, the notifier can save an incredible amount of energy by only activating the cellular connection once it actually needs to send a notification; which in this case takes the form of an HTTP request that eventually works its way to a Telegram group chat.

To cut a long story short, testing seems to indicate that the notifier can fire off approximately 800 requests before needing its 10440 lithium battery recharged. Given how often [Zak] usually receives mail, he says that should last him around five years.

The A9G module, the ATtiny402, a BME280 environmental sensor (because, why not?), the battery, and all the ancillary support hardware are on a very professional looking PCB. That goes into a relatively rugged enclosure that’s designed to keep the electronics from shorting out on the mailbox’s metal case as well as keeping any particularly weighty parcels from crushing it.

If you’ve got the freedom so mount whatever you want outside, then you can certainly build a more technically impressive mailbox. But considering the limitations [Zak] had to work around, we think he did an excellent job.

An Optocoupler Doorbell Notifier

Over the years we’ve seen several attempts at adding Internet connectivity to the lowly wired doorbell. Generally, these projects aim to piggyback on the existing wiring, bells, and buttons rather than replace them entirely. Which invariably means at some point the AC wiring is going to need to interface with a DC microcontroller. This is often where things get interesting, as it seems everyone has a different idea on how best to bridge these two systems.

That’s the point where [Ben Brooks] found himself not so long ago. While researching the best way to tap into the 20 VAC pumping through his doorbells, he found a forum post where somebody was experimenting with optocouplers. As is unfortunately so often the case, the forum thread never really had a conclusion, and it wasn’t clear if the original poster ever figured it out.

DIY optocouplers wrapped in electrical tape

[Ben] liked the idea though, so he thought he would give it a shot. But before investing in real optocouplers, he created his own DIY versions to use as a proof of concept. He put a standard LED and photoresistor together with a bit of black tape, and connected the LED to the doorbell line with a resistor. Running the LED on 60 Hz AC meant it was flickering rapidly, but for the purposes of detecting if there was voltage on the line, it worked perfectly.

Wanting something slightly more professional for the final product, [Ben] eventually evolved his proof of concept to include a pair of 4N35s, a custom PCB, and a 3D printed enclosure. Powered by a Particle Xenon, the device uses IFTTT to fire off smartphone notifications and blink the lights in the house whenever somebody pushes the bell.

If you’re still wondering why it’s so tricky to connect a microcontroller up to your door bell, a quick look at some of the similar projects we’ve covered should give you a pretty good idea of how annoying these systems can be to modernize.

A Wearable Space Station Notifier

If you don’t live in northern Europe, Alaska, or the extreme southern part of South America, there’s a 400-ton, $150 Billion space station flying over your head several times a day. It’s the International Space Station, and it’s the most complex and expensive construction project of all time. Look up at the right time, and you can see a point of light rising in the sky, brighter than any star, darting across to the opposite horizon.

ISS-Above is a simple tool that will tell you when you’ll be able to see the ISS passing overhead next, and the creator of the project, [Liam Kennedy] has a new crowdfunding project to turn this space station notifier into a wearable. It’s called the Pulsar, and with the help of an RFduino and a real time clock, it will alert you to an upcoming station pass with a bit of wearable electronics.

ISS
Viewing the ISS at the most recent Hackaday Pasadena Meetup.

The ISS-Above is a great device to keep tabs on the six astronauts currently orbiting our globe, but if you want to see the space station rise over the horizon… well, lugging a Raspi and an HDMI monitor outside isn’t the best solution. The Pulsar is a tiny wearable board with a ring of LEDs programmed with 50 future passes of the space station. When the station is overhead, the LEDs light up, and a bright object appears over the western horizon.

[Liam] brought his Pulsar to the most recent Hackaday Pasadena meetup, and as his wearable LEDs lit up, the ISS appeared right on cue. The evening was only tainted by a crazy lady who decided to argue the existence of the International Space Station.

Video below.

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Android Doorbell Notifier

Breadboarded circuit to detect when doorbell rings

It’s always unfortunate to find a FedEx tag on your door saying you missed a delivery; especially when you were home the whole time. After having this problem a few times [Lee] decided to rig up a doorbell notifier for his Android phone.

[Lee]’s doorbell uses a 10 VAC supply to ring a chime. To reduce modifications to the doorbell, he added an integrated rectifier and a PNP transistor. The rectifier drives the transistor when the bell rings, and pulls a line to ground.

An old Netgear router running OpenWRT senses this on a GPIO pin. Hotplugd is used to run a script when the button push is detected.

The software is discussed in a separate post. The router runs a simple UDP server written in C. The phone polls this server periodically using SL4A: a Python scripting layer for the Android platform. To put it all together, hotplugd sends a UNIX signal to the UDP server when the doorbell is pushed. Once the phone polls the server a notification will appear, and [Lee] can pick up his package without delay.

Mood Lamp/notifier Uses Neat Modular PCB Design

mood-lamp-with-modular-electronics

Not only does this mood lamp which [J. Sutton] built look great, but we love the modular design he adopted when building the circuit boards.

If you’re building something that is going to sit on your desk for some time it just has to look good. We think that he achieved that, using a small block of oak as the base, and a cloudy white cube of unknown origin as a diffuser. Notice that the different colors are not mixed. There’s a baffle inside the diffuser that keeps them separate as early testing showed any combination of intensities was resulting in nearly the same shade of color.

The part we really like is the modular design of his circuit boards. The project is based around a Teensy++ 2.0 board. He first built a PCB baseboard which feature two SIL sockets to accept the legs of the Teensy. There is a third SIL socket which accepts some long legs from the LED host board, letting it perch on top of the Teensy.

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Mailbox Notifier Texts When The Letter Carrier Arrives

mailbox-notifier

[Felix Rusu’s] mailbox is on the other side of the street and he’s got a pretty big front yard. This means checking for mail is not just a pop your head out of the door type of activity. This becomes especially noticeable during the winter months when he has to bundle up and trudge through the snow to see if his letter carrier has been there yet. But he’s made pointless trips a thing of the past by building a notifier that monitors the mailbox for him.

He’s using a Moteino, which is an Arduino clone of his own making. It’s tiny and features an RF module on the underside of the board which takes care of communicating with a base station inside the house. The module seen above rolls the microcontroller board up along with a 9V battery and a hall effect sensor which can tell if the mailbox door is open or closed. When the Arduino detects a change to that sensor it pushes some data back to the base station which then relays the info to a computer or Raspberry Pi in order to send him a text message. All of this is shown off in the video after the break.

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