We don’t blame the manufacturer of this GSM to Landline converter box for not designing the thing from the ground-up. After all, quantities of scale have made dumb-cellphones available for next to nothing. But you have to admit that it’s interesting to see a fully populated cellphone board creatively soldered into a consumer product. It would be commonplace if made in your basement rather than being sold in a store.
[Anton] was using the box to add his analog house phones to the cell network. The signal strength at home is pretty low and this box offers an external antenna for better reception. He cracked open the case expecting to see a GSM modem and was surprised to see the cellphone board. It includes a battery backup, and has been soldered directly to the cables which interface with the main PCB using some SIL connectors. Those solder joints were done by hand directly to the pins of the SIM card slot and as well as all of the other important connection points.
Here’s a challenge tailored to our community if we’ve ever seen one. You know those delightful unsolicited prerecorded calls you get from time to time? They might be political, but they also come from companies trying to sell you vinyl siding, or promising improvements in your business. Well they’re against the law in many cases, and complaints to the Federal Trade Commission have been piling up. So now the FTC is offering a $50,000 bounty to anyone who can find a way to block the calls.
It’s called the Robocall Challenge and you’ve got until January 17th, 2013 to get your entry submitted. The great thing is, this doesn’t need to be a fully working solution. Your entry may be: “proposed technical solutions or functional solutions and proofs of concept “. Even better, you retain ownership of the solution even if you win. This type of recognition will surely have telco related companies beating a path to your door.
Of course if you do have a solution, we’d love to hear about it too!
[Thanks Filespace via WCPO]
This pile of hardware marries telecommunications hardware from distinctly different generations. [Andrew D. Farquharson] wanted the retro look and operation of a rotary phone, with the convenience of a modern cordless. He combined the two technologies to achieve his goal.
The first problem was to find a way to translate the rotary inputs to something he could use. There are already a bunch of projects that use rotary hardware so he didn’t have to reinvent the wheel. He followed this guide to connecting Arduino to a rotary phone.
The next step was to interface with his cordless phone. He ditched the case and soldered rainbow ribbon cable to the entire button matrix. An opto-isolator is used to protect the Arduino while making each connection. Finally, he patched into the mechanism which monitors the cradle to see if the handset has been picked up. It sounds like his code lets you enter the number on the dial, then pick up the handset to actual transmit it through the cordless phone.
In case you haven’t noticed from my many comments on the subject, I drive a VW bus. It is a 1976 Westfalia camper with sage green paint and green plaid upholstery. I absolutely love it and so does the rest of my family. We go for drives in the country as well as camping regularly. We have found that the kids have a hard time communicating with us while we’re going higher speeds. These things aren’t the quietest automobiles in the world. Pushing this bread loaf shaped hunk of steel down the road with an engine that might top out at 75hp results in wind noise, engine noise, and of course, vibration.
I decided to employ a really old hack to put two functional telephones in the bus so my kids can talk to my wife (or whoever the passenger is) without screaming quite so loud. This hack is extremely easy, fairly cheap, and can be done in just a few minutes. The result is a functional intercom that you could use pretty much anywhere!
Continue reading “Using old phones as an intercom in your VW bus (or anywhere else)”
When [Bobo1on1] upgraded his Internet connection from ADSL to Fiber he ran into an issue of actually getting that speed to his desktop computer though his LAN setup. Before he had been using a telephone extension wire which ran from where the DSL entered the house, through a splitter, to his computer where the modem was located. Now that the router used by the fiber system is located at teh entry point, he has no easy way to run Ethernet cable to his computer room. Wifi is predictably slower than the 50mbit WAN connection, and he was unable to use the telephone cable as Ethernet directly.
The solution turns out to be a pair of TP-Link home plug adapters. These are designed to use your home’s mains wiring for data transfer. But [Bob] rigged it up so that they can push 224 mbits/sec over the telephone wire. Since you can’t run mains voltage through the telephone wire he had to hack a method to separate power for the devices from the data I/O. This was done with an external power supply and some passive components for filtering. The drawback is that this is half-duplex so up/down communications cannot happen at the same time.
On his blog, [Kenneth Finnegan] recently showed off a replica of a fun toy he used to play with as a kid, a telephone intercom system. The setup is pretty simple, requiring little more than a pair of analog phones, a battery, and a resistor.
The phones are connected to one another using a standard telephone cable, but [Kenneth] uses a 9v battery to introduce a small bias current into the loop, allowing the speakers at either end to hear one another. He also added a small LED into the circuit so that there is a visual indication as to when both handsets are off hook.
The setup is very simple at the moment, though [Kenneth] does have some ideas in mind to enhance his intercom system. He hopes to tweak the remote phone to ring when the local phone is picked up, among other things.
Telephone technology is nothing new, but for just a few dollars (or less) your kids can be entertained for hours as [Kenneth] was way back when.
Continue reading to see a short video overview of the phone system, and be sure to share your ideas for enhancing it in the comments section.
Continue reading “This toy intercom system is way better than a pair of tin cans and some string”
If you’ve ever wondered about the best way to detect dial and DTMF tones from a phone line, [Debraj] is your man.
[Debraj] built a DTMF detector using the Goertzel algorithm. Normally, when we think about detecting tones, we pull FFT out of our bag of tricks. The Goertzel algorithm isn’t as computationally complex as FFT and can be implemented on even the smallest microcontrollers.
For the build, the first thing to solder is a nice audio transformer and some protection diodes. The ring tone from a phone line goes from +35 V to -35 V – a bit more than a microcontroller could handle. A PIC18F4520 dev board was used as the brain of the system with all the code is available on [Debraj]’s site.
Although implementations of the Goertzel algorithm are a little uncommon, [Debraj] has seen a few interesting projects using this technique. [Debraj]’s build could easily be modified into a guitar tuner with a few changes in the code, for example.
This project was built as the command and control for a home automation system and from the video after the break, we can’t wait for [Debraj] to get annoyed at the phrase, “To turn on the kitchen lights, please press 1…”
Continue reading “Detecting DTMF tones from scratch”