Old-school Rotary Phone Gets GSM Upgrade

Sometimes, the answer to, “Why would you bother with a project like that?” is just as simple as, “Because it’s cool.” We suspect that was the motivation behind [Dirk-Jan]’s project to make portable versions of classic rotary telephones.

On style points alone, [Dirk-Jan] scores big. The mid-1950s vintage Belgian RTT model 56 phone has wonderful lines in its Bakelite case and handset and a really cool flip-up bail to carry it around, making it a great choice for a portable. The guts of the phone were replaced with a SIM900 GSM module coupled with a PIC microcontroller and an H-bridge to drive the ringer solenoids, along with a Li-ion battery and charger to keep it totally wireless – except for the original handset cord, of course. The video after the break show the phone in action both making and receiving calls; there’s something pleasing on a very basic level about the sound of a dial tone and the gentle ringing of the bell. And it may be slow, but a rotary dial has plenty of tactile appeal too.

Rotary-to-cell conversions are a popular “just because” project, like this conversion designed to allow an angry slam-down of the handset. The orange Siemens phone in that project is nice and all, but we really favor the ’50s look for a portable.

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Too Hot For Fido? Get Alerted!

Meet project Oro, the temperature monitoring watchdog. Err… the watchdog monitoring temperature probe. Well, it’s both actually!

[Richard Deininger] built the project after having the AC system go down in his company’s server room. That environmental cooling is imperative if you don’t want your server hardware turned to slag. The idea is a separate piece of hardware that monitors the room temperature and will alert the on-call staff if it climbs too high. He was successful, and showing the hacked hardware around the office came up with a second idea: a temperature sensor for your car to ensure it’s not too hot for your dog.

Anyone who has a canine friend living with them knows you don’t utter the word “ride” out loud lest a barking, whimpering, whining frenzy ensue. But jingle those keys and they’ll be at the door in no time. During the summer you can still take them with you for short errands thanks to the peace of mind [Richard’s] build provides. It’s simply an Arduino, DHT22 temp/humidity probe, and a SIM900 GSM modem. Set your temperature threshold and you’ll get an alert if temperatures are climbing to unsafe levels for Fido.

While you have your tools out, we recommend building auto-watering and auto-feeding systems for the family pets. What’s that? You hate domesticated animals? There’s a hack you can use to chase them from your yard.