phone ?

Discussion in 'General Electronics Chat' started by Mathematics!, Dec 15, 2009.

  1. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
    1,022
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    Ok , I had an old corded phone.
    So I had the brilliant idea of connecting the green/red wires to the main 120VAC 60hz house outlet.

    Since 90vac ring is only 30vac away from the house and 60hz is only 3 times that of 20hz ring....

    It worked fine until I picked up the phone and then it started smoking....
    It is still useable but doesn't work very well.

    what I am curious about is what destroyed it would it have over heated if I left the phone on the hook eventually or was it completely from the fact that the phone went of the hook that killed it? (never did factor in the current which for phones would be typically in the mA where as wall amps is probably much greater ...but it didn't seem to effect it until I picked up the phone)

    Also I built a timer 555 circuit that outputs a 20hz square wave.
    It uses a 9volt battery so I am wondering how I can add-on to the
    output so I can ring the phone by attaching it to the green and red wires of the phone.

    I would think I have to increase the output voltage to 90volts from the 4.5volts it is at now for the output....

    Can I do this with a homemade transformer from a coil of wires?
    Also this is plusating dc is this ok to use or do I have to create an inverter circuit.....dun
    I would think the transformer should work with pulsating dc because it is still a change in current which induces a changing magnetic field.....

    But the question is can the phone ring with pulsating square waves or must it be ac sine waves?


    Any suggestions are welcome.
    I beleive this is called an orange box in the phreaker community?
    Thanks again
     
    Last edited: Dec 15, 2009
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Do you understand that busily messing around with line voltages can not only kill you, but cause other problems, like fires? How close to killing yourself did you come when disconnecting that old telephone? Was the already thin insulation awfully hot and gummy?

    I suppose we need to add this to the rest of the safety rules - Never, under any circumstances, attach anything to a source of AC power that is not intended to operated by the AC line.

    We do not discuss illegal actions or devices. This is not something to pursue on AAC.
     
  3. BMorse

    Senior Member

    Sep 26, 2009
    2,675
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    :eek:! HSB!!

    I think you need to take some basic lessons in safety and common sense before you delve further into this as a hobby.... before you or someone else gets hurt or looses their home....:cool:
     
  4. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
    1,022
    4
    First of all I was fully am aware of the risks.
    I used the circuit breaker to disconnect / reconnect the phone.
    So I was pretty much safe. (for the most part)

    Second the telephone wire was not at all hot.
    Maybe a little warm at best.

    Ok , hacking stuff does not get talked about on this fourm. I understand that sorry and I will try not to talk about this hacking stuff anymore on this forum.

    But we could at least talk about the timer 555 20Hz circuit and how I can bump it up to 90vac 20hz instead of 4.5volts pulsating dc 20hz for the output? And if I need to convert it to a sinewave and how?
     
  5. S_lannan

    Active Member

    Jun 20, 2007
    247
    2
    i lol`d hard.
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
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  7. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
    1,022
    4
    Anybody on this question

    what do I have to do to convert the output of my circuit into 90vac , 20hz sinewave???

    Thanks for your comments
     
  8. lmartinez

    Active Member

    Mar 8, 2009
    224
    6
    It can be accomplished with the appropriate circuit modifications.:)
     
  9. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
    47
    A breaker will not help much. A Ground Fault Detector will help some. Why not keep the voltage under 50 or 25 v for a while?
     
  10. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You really need to stick to circuits that are under about 45v.

    For quite a while.

    You might know math, but you seem to have a very limited concept of how dangerous your experiment was.
     
  11. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
    1,022
    4
    Well it will protect me from current over 15 amps :)


    yes , but I am looking for a simple add on to my output not something I have to build with a 100 components and have to send away for parts something quick and easy...

    Just want to know what I have to add to the output to make it 90vac 20hz.
     
  12. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Do yourself a favor.

    Download LTSpice from Linear Technology's site.

    Google is your friend.

    Then join the LTSpice group on Yahoo.

    You understand math better than I ever will.

    As of this moment, I understand electricity/electronics quite a bit better than you do.

    Electricity and electronics is all mathematics.

    Extrapolating from what I have just said, you will eventually understand electricity and electronics much better than I do.

    We are just trying to keep you from killing yourself in the meantime.
     
  13. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    Darwinism never sleeps. :D
     
  14. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    If you stepup the 4.5V from your 555 oscillator to 90V then the 100mA max output current will be reduced to 4.5/90 x 100mA= 5mA which is probably not enough current to ring a phone. Also, the output voltage of a 555 oscillator drops when it is loaded so the voltage will probably be too low.

    A 90V square-wave has double the average power of a 90V sine-wave so the bell might be over-heated. But the peak voltage of a 90V sine-wave is 127V so a 90V square-wave might not have enough voltage to ring the bell.

    When a phone goes off-hook then the telco stops the ringing immediately. Yours didn't. So its parts that are designed to operate at a low current on low voltage DC got blasted with 120VAC. An off-hook phone has no more than 9VDC across its wires. You can hold 9VDC in your hand and won't feel it. Don't try holding 120VAC in your hand and don't apply it to an off-hook phone.
     
  15. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,696
    904
    You can drive a low-side, N-channel mosfet with your 555. Just use a common ground and a mosfet appropriately rated with a separate 90V DC supply. You can easily get 1 A of current supply.

    John
     
  16. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    As a lead tech for Collins I saw a tech on my line get knocked on his ass from 48VDC, I asked if he was OK, he said he was, and I started laughing. He never did forgive me for that.
     
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