cellphone to tinker with

Discussion in 'General Electronics Chat' started by jarwulf, Oct 17, 2013.

  1. jarwulf

    Thread Starter Member

    Jul 7, 2013
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    I'm a beginner who is very interested in making an oldstyle rotary cellphone. I'm wondering if converting a contemporary cellphone would be the easiest way to do this or maybe, just throwing this out there, working with something like a raspberry pi


    If a regular cellphone was easiest I was looking for suggestions on an ideal cellphone to purchase for a conversion. I assume that the oldstyle one piece feature phones with basic text functionality consisting of a simple screen and keypad would be easier than a flip phone or a smartphone or an iphone style device so I'm looking for something like that. I also would like something that has as much info as possible on its internals and how to modify it. Also something that was popular so they'd be easy to buy and cheap to purchase for experimentation.

    Thanks.
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Rotary Cell Phone?
    The only portable phone I knew of that was rotary was not Cell technology, but point to point radio transmission?
    The technology of rotary phone is to count a number of pulses on the return of the dial, the cell phone uses tone recognition for each number.
    Max.
     
  3. crutschow

    Expert

    Mar 14, 2008
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    I think we have a little time warp here. ;) There has never been a rotary dial cell phone, only rotary dial land-line phones up until the 1980's or so. To use a rotary dial with a cell phone you would need to convert the number of pulses to the appropriate DTMF frequencies for that number. That could be done with a microprocessor and a DTMF chip. Then you would need to input the DTMF tone to the cell phone to make the call. Sounds like a reasonably complex task.
     
  4. Sensacell

    Well-Known Member

    Jun 19, 2012
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    Super cool project idea!

    Use a micro controller to count the dial pulses from an old-school rotary phone, then interface the micro controller to trigger the buttons on the cell phone.

    You could embed the whole thing into the case of the old phone, lots of room in there!

    Extra credit: Make the original bell ring when you receive calls!

    Hang around in public places and make calls on your wireless rotary phone= massive geek cred.
     
    Last edited: Oct 18, 2013
    #12 and PackratKing like this.
  5. PackratKing

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    Jul 13, 2008
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    ROFLMAO... Thanx for the good laugh !!
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    There was a 'Portable' dial phone available in the 80's that was the size of a small suitcase, Radio transmission back to the Telephone company, I am not sure if it was AM or FM?
    Probably AM.
    I had to take a trip up to a Gold Mine in the Canadian North to check some equipment and we took one along, the reception was rather spotty and depended on the time of day!
    Max.
     
  7. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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  8. Sensacell

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    Jun 19, 2012
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  9. MaxHeadRoom

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    I have an operating rotary phone in my garage, I have had to teach the Grand kids how to use it!
    Max.
     
  10. jarwulf

    Thread Starter Member

    Jul 7, 2013
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    As a start I would appreciate some suggestions on mobile phones that would be ideal to tinker with ie simple as possible, widespread, cheap, with tons of documentations and howtos so I could learn my way around it. Just a basic phone with maybe some text capabilities and sim card. Or are all the old mobile phones similar enough that it doesn't matter?
     
  11. crutschow

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    Interesting. Of course those were radiophones with one land transmitter in each area that had a very limited number of possible users, since not more than one phone could use a channel at a time. That's quite different from a modern cellphone network.
     
  12. #12

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    Nov 30, 2010
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    I have a pulse dialer that still works. I wonder how the phone company interprets the dial pulses. Probably nothing simple or we would try to copy it.:D
     
  13. MaxHeadRoom

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    They count them on the dial return at the governed rate, this is why you have to remove your dial finger at the end of the stroke, otherwise a double number can be counted if a delay is introduced.
    Max.
     
  14. #12

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    Nov 30, 2010
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    Yeabut...what do they count the pulses with?

    I didn't say I have a rotary phone. I have a pulse dialer. Push the button, it pulses x number of times. The wondering is about the phone network having some simple way to interpret pulses, long after DTMF became standard. Dedicated chip? An app for that? A trivial part of a huge networking chip?
     
  15. MaxHeadRoom

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    Up until the 80's the old stepper relay exchanges could be found in small private exchanges in building and plants.
    The pulse would ratchet the contacts up and then the next string would step it across, the pretty noisy to be in one.
    http://strowger-net.telefoonmuseum.com/tel_tech_sxs.html
    I have a working dial phone so I assume they also have a detection of some kind as I use the same line as the DTMF phones.
    Max.
     
  16. crutschow

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    It wouldn't be hard to add a pulse counting option to the processor that, I assume, handles all the call processing and routing. It it detects a pulse, then it counts those. It it detects a DTMF tone then it decodes that. I have an old rotary dial telephone and it still works to dial out on my local phone line.
     
  17. Sensacell

    Well-Known Member

    Jun 19, 2012
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    I think you will find using cheap cell phones to be difficult:
    No documentation, microscopic connectors with no available mates, etc.

    Manufacturers of consumer electronics have zero incentive to release any technical documentation.

    An OEM cellular module will be your ticket.

    http://www.roundsolutions.com/techdocs/ds/AarLogic-T60N-4_Manual.pdf
     
  18. jarwulf

    Thread Starter Member

    Jul 7, 2013
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    A rough list of parts I may need

    Candlestick rotary phone: probably replica. Real ones are too expensive. Most replicas are touchtones and it seems too complicated to attach a dial to one. A few replicas have actual dials though $40+. Maybe a modern 'replica' could be a tone phone and save me some trouble? How could I tell?

    Cellular module: Unfortunately most of the instructional material for various modules shows people connecting it to a computer and leaving it at that. I'll have to figure out how to integrate it into an actual phone. $60
    +
    Breakout board?: $60
    +
    antenna: $15

    or

    secondhand mobile phone: $???


    DMTF converter: There are some ready made ones but these seem mostly geared to converting landlines to landlines and are like this http://www.dialgizmo.com/ $40

    Key hurdle: Would it be possible to somehow connect the dial to the module with the converter?

    Secondary Hurdle: How would you power the whole thing? The converter looks like it gets its power from the phone socket.
     
    Last edited: Oct 22, 2013
  19. jarwulf

    Thread Starter Member

    Jul 7, 2013
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    Would it be feasible to connect a rotary phone to a cellular module via the DTMF type device above? Or is there a better way?
     
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