Use of signal generator for inverter

Discussion in 'General Electronics Chat' started by apurvmj, Nov 7, 2015.

  1. apurvmj

    Thread Starter New Member

    Sep 28, 2012
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    Hi all,
    Coming straight to the point
    In inverter, we normally use AC signal, generated by various means and the same is amplifed to feed the primary of center tap transformer of inverter. So we need center tap transformer at the primary side.
    Can we use function generator to produce sine wave to be used in inverter. But in function generator we have one ground and one signal wire. So how can we feed the signal to center tap transformer.
    I hope I have made the question clear.
    Thanks
    :)
     
  2. crutschow

    Expert

    Mar 14, 2008
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    If you are referring to a DC to AC power inverter than the usual way to generate a sine wave output is to provide a sine-wave modulated PWM signal to the primary.
     
  3. tcmtech

    Well-Known Member

    Nov 4, 2013
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    A signal generator followed by a large audio amplifier followed by a transformer will make for a fairly decent power inverter but why bother when properly designed and built one can be bought for cheap and broken ones that could be fixed can be had for almost free.
     
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  4. Brownout

    Well-Known Member

    Jan 10, 2012
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    The signal from the function gen can be half-wave rectified into a positive half and negative half wave. Each can be connected to the end connections of the xfmr, with ground connected to the center tap. This would result in a workable, but terribly inefficient inverter.
     
  5. ian field

    Distinguished Member

    Oct 27, 2012
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    Even the professional kit UPS boxes ruin the battery if they're not called upon to supply power fairly often.

    There used to be a computer breakers yard in the next town, there was regularly a line of UPS units waiting for someone to process the recoverable metals.

    Most of them would have been good as new with replacement batteries - but SLA batteries don't leave much change out of the price of a new UPS.
     
  6. tcmtech

    Well-Known Member

    Nov 4, 2013
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    And that relates to what exactly? o_O

    Definitely another good source for basic power inverters on the cheap. I think I have at least 10 old UPS units laying around now that I got for nothing due to the batteries going bad. :D
     
  7. tcmtech

    Well-Known Member

    Nov 4, 2013
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    What? o_O

    Got a schematic to back that claim up being I think there are considerably far more parts involved than just a bridge rectifier and a transformer?
     
  8. Brownout

    Well-Known Member

    Jan 10, 2012
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    It's basic electronics

    interter.JPG
     
  9. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Um... Yea. Okay.... :oops:

    I'll let someone else break it down for you. :rolleyes:
     
  10. Brownout

    Well-Known Member

    Jan 10, 2012
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    I just did.
     
    Last edited: Nov 7, 2015
  11. Lestraveled

    Well-Known Member

    May 19, 2014
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    I get it. The circuit is a little glitchy, but it will work if the output is floated.
     
  12. ScottWang

    Moderator

    Aug 23, 2012
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    I think you should adding the ID of member in your replied, it will more easy to identify who you've replied to.
     
  13. Brownout

    Well-Known Member

    Jan 10, 2012
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    Indeed. An improvement would be to replace the outside pair of diodes with a transistor pair biased to minimize the crossover flatband.
     
    Last edited: Nov 8, 2015
  14. tcmtech

    Well-Known Member

    Nov 4, 2013
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    I was referring to brownouts circuit that adds four diodes to a transformer circuit to break up a AC signal into its two halves just to have the transformer put it back together again for no reason. :rolleyes:

    As he has it drawn he is taking an AC signal (of which the transformer would handle just fine as is and is converting it into a pulsating DC signal at twice the original AC signals frequency) and is pulling it out of both the upper and lower halves of the center tapped winding in alternating half cycles to get the original AC signal back out so it can be transformed.
     
  15. ScottWang

    Moderator

    Aug 23, 2012
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    You already have 3 posts in this thread had replied but without any ID of members, see #6, #7, #14(replied me), that's why I pointed out.

    And In other two threads in #12, #28, are you get used to it?
     
  16. Brownout

    Well-Known Member

    Jan 10, 2012
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    Which is exactly what the OP asked and I described in my first post. You falsely claimed it would take "far more parts."
     
    Last edited: Nov 8, 2015
  17. apurvmj

    Thread Starter New Member

    Sep 28, 2012
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    0
    Hi friends,
    With respect to power inverter
    I would like to know the difference between signal fed to center tap transformer and by that of signal generator.
    Coz with the signal generator you would not require center tap transformer. Am I right.
    PWM method is fairly complex than signal generator for sine wave generator, so why isn't it a favorite method of generating sine wave?
    This would help me understanding how electricity works.
    Thanks.
     
  18. Brownout

    Well-Known Member

    Jan 10, 2012
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    Transforming a signal by using the center tap produces twice the voltage at the transformer secondary output compared to using the primary end connections only. However, just because you have a center tap on the transformer primary, you don't have to use it. You may connect the sig gen directly transformer, either between center tap and primary end connectors (not recommended), or just between the end connectors. But using a sine wave is inefficient. It's more common to use PWM due to much higher efficiency.
     
    Last edited: Nov 8, 2015
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  19. ian field

    Distinguished Member

    Oct 27, 2012
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    Quite a few chemistries lose their ability to hold a charge if they're only ever float charged.

    All the SLA batteries I've examined from scrapped UPS units, were bone dry and heavily sulphated.

    In many cases I've found automotive batteries that have been stored on a maintenance charger are a little weak on return to a vehicle, but pick up after a few charge/discharge cycles and free use of the electric starter.

    The TS could get a perfectly good UPS inverter from anywhere that handles computer scrap - fit a new battery and its good as new.
     
  20. tcmtech

    Well-Known Member

    Nov 4, 2013
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    So what exactly is your end goal in this? If you are thinking that by sending the signal directly out of a common signal generator through a transformer will give you some form of usable AC power you are greatly mislead.

    As for the center tapped transformer all it is exactly what its name implies. A transformer with a tap at the midpoint of one of its windings. Nothing magical or mysterious about how it works.

    Now relating to brownouts schematic I see no advantage to that design other than to take a simple concept and add more parts to make it less efficient.

    Basically without you defining what it is you are intending to do or learn to understand all we can do is speculate on things and offer little to no reasonable advice towards designing anything in particular.
     
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