Need Adaptor Circuit

Discussion in 'The Projects Forum' started by naveed, Sep 18, 2009.

  1. naveed

    Thread Starter Active Member

    Mar 12, 2008
    42
    0
    I am using ADSL modem which uses an adaptor for power.

    OEM AC adaptor
    Model No: AA-091ABN
    Input: 230V~50Hz 95mA
    Output: 9V~1A

    I want to give the power to my modem by a 12V DC battery. Anyone can plz tell me the circuit?

    I also want to use the battery while charging. Actually here(in pakistan),
    load shedding is a serious problem.
     
  2. JDT

    Well-Known Member

    Feb 12, 2009
    658
    85
    Use a 3-terminal low-dropout regulator on a heatsink.

    See:- http://www.national.com/ds/LM/LM2940.pdf

    This data sheet has a typical circuit on the first page. And you can get a 9V version - LM2940CT-9.0
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Getting parts in Pakistan might be a problem.

    Attached is a simple linear regulator that just requires a power NPN Darlington with a heat sink, a 10v Zener diode, a 1k resistor and a capacitor on the output. The capacitor can be 0.1uF to 10uF; I used a larger one due to the load being a DC motor.

    If you don't have any 10v Zeners available, you could use a couple of lower-voltage Zeners in series.

    A "true" regulator IC would be much better, like an LM317, LM350 or LM338. The low dropout regulators like JDT mentioned would be even better, but you may have a hard time finding them.
     
  4. naveed

    Thread Starter Active Member

    Mar 12, 2008
    42
    0
    I am very thankful to you giving time for me!

    But I need some more help. Actually I am beginner in electronics and some questions arise in my mind regarding this circuit.

    What is M1 in the circuit?
    V1 is the voltage I have to give to the circuit? If yes then it must be DC?
    Output is across C1?
    What are A and B mentioned in the circuit?
     
  5. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    You state in your first post the adaptor is 9 Volts AC.
    Does the modem need 9 Volts AC?
    What kind of moden is it?

    Greetings,
    Bertus
     
  6. naveed

    Thread Starter Active Member

    Mar 12, 2008
    42
    0
    It is an external ADSL modem. ZTE zxdsl 831
    And it is written on the adapor for output: 9v~1A

    I think it is AC voltage for output. But I don't know how to check.
     
  7. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    Strange in the manual is written in chapter 5 18 Volts AC 9 Watts.
    See attachment.

    Greetings,
    Bertus
     
  8. naveed

    Thread Starter Active Member

    Mar 12, 2008
    42
    0
    No, I was asking about the circuit posted by SgtWookie.

    Dear, SgtWookie! where are you? Please help me.
     
  9. naveed

    Thread Starter Active Member

    Mar 12, 2008
    42
    0
    I think I am asking stupid question. I shouldn't.
    But bertus says
    when you do ask questions, you may look stupid.
    When you do NOT ask questions, you will STAY stupid.
    I don't want to be stupid.
     
  10. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Sorry, I didn't see your questions until just now.

    That is an electric motor. The schematic was from helping someone else months ago, I just used it because it was available. Your project would not have a motor.

    Yes, sort of. V1 is shown as a voltage with ripple on it, just to illustrate that noise on the input will not be on the output. V1 should be 11v up to perhaps 18v DC.
    Yes.
    Look at the simulated oscilloscope display on the bottom.
    B is the input voltage. You can see that it has an AC voltage on a DC level.
    A is the regulated output voltage.
     
  11. naveed

    Thread Starter Active Member

    Mar 12, 2008
    42
    0
    I am very very very thankful to you SgtWookie and this form.

    Thanks a lot.
     
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