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Telephone circuit advice

Discussion in 'Electronic Basics' started by Diefenbaker, Dec 14, 2004.

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  1. Diefenbaker

    Diefenbaker Guest

    Im looking at building the Smart Phone Light at

    It looks relatively easy for a novice. My question is regarding the +5v
    coming off or perhaps better said going to the IC3 (A) Pin 16.
    Does this mean that I should use an AC/DC adaptor to apply DC +5 volts here.
    And does the negative of this go to the Ground symbol at the bottom.

  2. CFoley1064

    CFoley1064 Guest

    Subject: Telephone circuit advice
    Hi. It does mean you'll need an external power source. Since you've got TTL,
    you'll need a well-regulated 5VDC +/- 0.25V supply for this to work.

    If you've got a little room, get a 9 to 12VDC wall wart, a 7805CT regulator and
    a couple of 10uF, 25V electrolytic caps and do something like this (view in
    fixed font or M$ Notepad):

    | |
    | 1|____|3 |
    | 2| |
    +| | +| 5VDC OUT
    9VDC IN --- | ---
    --- | ---
    | | |
    | | |
    | | |
    | | |
    created by Andy´s ASCII-Circuit v1.24.140803 Beta

    Pin numbers on the 7805 are looking from the front (plastic side) of the TO-220
    package, pins down, from left to right. These parts will be available at any
    hobbyist source.

    This will give you the regulated 5VDC you need.

    And, oh yes. The negative side goes to the GND symbol at the bottom.

    Good luck
  3. Diefenbaker

    Diefenbaker Guest

    I'm the first guy called when the alarm goes off for the company. I hate
    fumbling around in the dark.
    Im sure I could buy somthing like this, for less than it will cost to make.
    But what would be the fun in that?

    If anyone could answer the following question as well...
    I have tried to buy (C1) 1.u 400v Capacitor. But my local guys dont have
    anything like this. Could I use something else. I did see 1u 250v but 400v
    seems a little excessive, acept for spikes I suppose but I think everything
    would go if it got that high.

    Secondly Im asuming that the +1000 could be a 16v cap.

    Finally the Relay I guess needs to be 5v relay. The diagram smudges the
    number. But asuming that the voltage there is 5v DC.

  4. Diefenbaker

    Diefenbaker Guest

    Hey Chris thanks for the answer.

    Specially on the view in notepad. Do you know how many times Ive looked at
    diagrams in news groups and thought why so people put them in cause I dont
    know what font and spacing they used. Its given me a whole new perspecive on
    some of the diagrams I have seen and passed up because I could not figure
    out how they went together. What A fool Ive been.

  5. Jamie

    Jamie Guest

    it means you should be using a regulated source or a source that is
    rather stable around 5 volts to power up the circuit.
    would this be used to detour some one into thinking your home if
    the phone rings? or simply an auto night lamp when the phone rings
    to see your way to the phone?
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