Taufeeq's Geek Pages
written specially for
CREATIVE COMMONS LICENSE
All electronic diagrams, articles, softwares including source code and concept designs by Taufeeq Elahi Diju are licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License. Based on a work at www.taufeeq.com
Please read the license before utilizing the material given in this document in your own work.
What is my HyperPhone ?
HyperPhone is a hack performed on a regular phone to make a quick dialer for it. A system that sends appropriate tones for a specific number to the exchange when a button is pushed. Many such projects have been done in the past but this one adds some more features to the original idea of one touch phone dialing for landlines.
Why did I build it ?
My grandmother has severe eyesight problem and cannot read numbers on the telephone keypad properly, and also, due to old age cannot remember all the long mobile numbers of family members. So, the idea was to build a simple to use phone with minimum number of buttons on its front, also they should be glowing so that she could find them easily in dim light/dark.
What will I provide here on this page ?
Here you will find get A - Z detailed plan for building one of your "HyperPhone" if you like the idea or need for someone disabled/senior citizen. I will provide pictures of construction, components used, full schematic of the circuit that I designed and also the source code and the hex file for microcontroller. More over, I will be glad to help anyone building it or anything similar to it anytime through email. info[at]taufeeq.com Please don't hesitate to fire an email if any assistance is needed.
Hooking yourself into the telephone line...
Well the basic idea is, you press a button, and a microcontroller operates a DTMF ( dual tone multiple frequency ) IC to send tones to your local exchange. when the sequence of tones is successfully sent, your call is dialed - thats so simple. In other words, instead of dialing numbers on the telephone keypad with you hand, a microcontroller will be used to send the tones using a tone generating IC. There are many circuits available on the internet that show how to send DTMF tones on your landline. ( Interface between the DTMF IC and your telehone service line ). I have tried many but it did not work for me. So i decided to solve the riddle in a different way. here is what i did : I hacked open an old telephone set that was trashed in my store room and connected a 1:1 transformer to its microphone connections and connecting the DTMF IC to other end of this isolation transformer. If you are not following me, dont worry, you will understand it eventually when i describe the circuit.
Here we go...
In the image above you can see an old plastic body of some device that i am modifying with my solder iron for housing the buttons and cradle.
To create glowing buttons, i borrowed the idea from one of Hack-a-day entries (thanks!). In the original idea given on hack-a-day, an LED was placed on top of two microstates. But here, I changed the flavor of the recipe by taking a faily big microswitch as you can see above in slide 1, and instead of an LED, i used a square 1 cm x 1 cm two color backlight. This backlight that i used has three legs ( as seen in slide 2 ) The middle leg of the backlight is common 5 volts, and legs 1 and 3 are hence for ground. The backlight can provide red and yellow light depending on which ground ( Leg 1 or leg 3 ) you connect to the ground. grounding of legs 1 and 3 will be done by using a simple NPN transistor in switching mode. More on how the backlight is wired will be discussed later. In slide 3, you can see i am using a kind of superglue to join the backlight and the micro switch. This specific bonding agent that i have used gets very hard when dry and nearly impossible to break. There must be similar bonding tubes available in your country as well, so you better know what to use. ( here its called Magic Depoxy , please note in many countries "Epoxies" are available from hardware stores which sell nails, screwes hindges etc - you can use Epoxy too). In slide 4, you can see how the final dried unit looks like - a bi color glowing button.
In the above four slides you can see that i am modifying an old receiver of a telephone and connecting a thin metal rod ( U shaped ) to it. this will be used to hand the receiver on the set. This is ofcourse the old style of telephones what used to exist in the times of ghram bell, but its the most convenient system for cradle operation for people with poor vision. the large hook U shaped collar provides ease in hanging it on the hook. (the hook on the custom designed telephone set will press the limit switch to operate cradle.) So, when you hang this receiver on the hook, the hook move down due to weight and presses the small limit switch. In slide 3 you can see that i have put a shrinkable seleve on the U shaped rod so that it looks better in black color. This receiver did not work well in the end as it had some problems in its microphone, so i had to repeat the whole processes of opening it and placing this U-shaped collar to that one. This specific receiver was a bit small and i liked it more, but eventually had to go with a larger sized that you will see in pictures in a short while.
In the above slides you can see that i am joining two limit swtiches together with the same epoxy tubes and then putting a small connecting rod on top of them. So when i push the rod, both are activated. I really did not need two buttons, but the limit swtiches i had with me at the time of building did not have a strong spring inside them. So, if you have a bigger limit switches that needs more force to press, its okay to use just one.
Okay then, in the above slide 1, what you can see is the circuit of a land line telephone. And in slide 2 you can see the zoomed image of the cradle button. it is the button that gets pressed when you put the receiver on your telephone set. In slide 3, you can see that i have removed this cradle button and it leaves 6 solder holes behind. I have labeled them A, B, C, D, E and F. I have removed the cradle switch because i am going to pack this whole circuit in a box at the end of the day, and what i will need the cradle not in that box, but on the wall ! ( inside the black casing - the very first slides on this page.). So, the microswtich that we just prepared will go into that black casing, and when the receiver is hanged on a hook, it presses the microswtich. the microswtich is connected to the microcontroller and the controller operates two relays. these two relays will actually operate the cradle. How we will use relays with these marked solder holes, it will be shown later.
In the above slide 1, you can see that i have made a hole in the casing. In slide 2, I have fixed the limit switch just infront of the hole i made earlier with epoxy. and In slide 3 you see a hook that i put through the hole. Its done in a way that when something in suspended on the hook, it will press the limit swtich inside. Slide 4 shows the back of the casing. Behind the pieces of vero baord, you can see there is a nail. this nail is the turning point for the hook's shaft.
Above in slide 1, you can see how the two bi-color switches look after i put them inside the casing. Slide 2 shows the backside of the casing and how i used epoxy to fix them in there. slide 3 shows how a 1:1 isolation transformer looks like. ( just for reference if you have never used it in any project.) and in slide 4, i have wired the cradle solder points to my two relays. Dont worry, i will explain how those ABCDEF points will be connected to relays.
In the above slide 1, you can see, its time to join the two parts of the casing. In slide 2, you can see, its up!. In slide 3, i have done all the wiring for cradle, two microswtiches, and the two bi color backlights. In slide 4, you can see, its a general purpose microcontroller board that i had built for another project. The header pins are the input/output pins. In Slide 5, i built a small DTMF circuit that will be run by microcontroller. And finally in slide 6, you can see how i put a 12 volt DC power supply, microcontroller board, DTMF board and the telephone circuit along with relays inside a metal box.
In the above three snaps you can see how it looks in my grandma's room. The above button dials a call on my dads mobile, and the lower dials calls on my moms mobile!
Simply pick the receiver, press the glowing button, and talk!
Video available on YouTube. I did not have a proper DV Cam, so there is no sound, and the mobile screen will not be clear.
Lets have the technical stuff - show me how to build HyperPhone electronics ! >>>