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Auto-switching device

  1. Jul 3, 2010 #1
    how to make auto-switching device using transistor??
  2. jcsd
  3. Jul 3, 2010 #2
    Please describe what you want to switch
  4. Jul 3, 2010 #3
    i want make simpler key

    Attached Files:

    Last edited by a moderator: Apr 25, 2017
  5. Jul 3, 2010 #4
    I don't know what you mean by a 'simpler key'.
    Do you want to replace the switch with a transistor?

    Please tell us what the circuit is for, and where those outputs go.
  6. Jul 3, 2010 #5
    ys i want to replace the switch by transistor and i want a way to make the transistor base currents vary from zero into some value so the transistor will act as auto switch and then i can convert the input dc voltage into ac and the transformer work..
  7. Jul 3, 2010 #6
    Tf I have read this correctly, you want to use the circuit as the centre of a DC to AC converter. Is that correct?
  8. Jul 3, 2010 #7
    yes ...
  9. Jul 3, 2010 #8
    When you control a current by using a transistor, the transistor gets hor just as a resistor would if it were soaking up the power. So to operate the transistor in a half-on mode makes the transistor get hot and lots of power gets wasted.
    Usually, people wanting to produce AC power from this kind of circuit do not use the "half-on" mode of the transistor. They switch the transistor fully on and fully off, and rely on filtering to clean up the resulting mess.
  10. Jul 3, 2010 #9
    You can most easily drive the new transistor from an opto-coupler or pulse transformer.
    There will be no need to filter the output from the new transistor, in fact you want about as unfiltered an output as you can get. The current from your new transistor is a tickler for the power transistors; it initiates a cycle of current in the high power part of the circuit.
    I think it likely that the load will be critical for the operation of this circuit since feedback from the load enters the power driver circuit.
  11. Jul 3, 2010 #10
    thnx for info. do you know simple way to convert the dc into ac without transistors??link me the way if you know
  12. Jul 3, 2010 #11
    Anything that actually works has to be simple on some level, but the question is too broad for a short answer.
    Good men have spent their lives on power supply design; the results of their efforts are not to be summed up in a few words as a 'done deal'.

    I suggest that if you are really interested in learning a bit more you'd probably find the study of electronics rewarding.
    Depending on what you want to design, electronics design work can be reasonably easy, and it is very satisfying to implement one's ideas in the real world!
  13. Jul 3, 2010 #12
    see that vedio .... that is what iam taking about... how can he convert the dc into ac by using the transistor ... my idea is the transistor he use doesnt reverse the dc current in the transformer it only pass the current in two oppesit direction I1 and I2 as shown on my attach. paper ,and those currents still cannot operate the transformer coz they still dc currents,,, pls if any one can help ????????

    Attached Files:

    Last edited by a moderator: Sep 25, 2014
  14. Jul 5, 2010 #13
    I looked at the video, and although I could not hear the sound and can't comment on all the details, I can see that the heart of this device is the transformer.
    A transformer is an inductor, which produces an large output voltage when input current is changed quickly. When switching the transformer on and off, current changes rapidly and a high voltage can appear for a short time.
    Please take care with this sort of thing, it is the kind of thing people are often careless with but there is always the chance of causing a heart attack, even in a healthy person.
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