555 timer inverter

Discussion in 'The Projects Forum' started by jayashree95, Jul 8, 2010.

  1. jayashree95

    Thread Starter New Member

    Jul 8, 2010
    5
    0
    I am using 555 timer circuit for 12V to 220V AC inverter and circuit u can find in the attachment but iam not getting 220V at the secondary of filament transformer. Currently i am getting 100V AC please suggest me improvements in the circuit or some other simple circuit.
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    This has come up in another thread, same schematic. A conventional 555 drops 1.4 volts from Vcc when it is fully on, plus you have another 0.7V loss across each Base Emitter junction. Basically the design isn't very good, it is lossy to the extreme. What is the transformer rated for specifically? Volts on both sides is needed.

    When I get a chance I'll look up that other thread and post the link, if someone doesn't beat me to it.
     
  3. jayashree95

    Thread Starter New Member

    Jul 8, 2010
    5
    0
    ok fine the max drop will be around 2.5V but i am getting transistor output as 12V peak to peak right then i should get exact AC voltage. Transformer specification is 0-12V at the primary and 0-220V at the secondary and current rating is 1A. can u suggest me for boosting the voltage at the transistor output. Please reply its urgent...
     
  4. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    If your power supply is 12V (an assumption on my part) you will get 9.5V to the transformer. It will also be a square wave, the inductor and capacitor will not cut it (indeed, they will reduce it further). 9.5VP-P is 4.2V RMS (square wave), and with an approx. convertion of X20 (slightly less) it will be 85V RMS. Sound familiar? Like I said, the design sucks.
     
  5. jayashree95

    Thread Starter New Member

    Jul 8, 2010
    5
    0
    so i have to do to increase the AC voltage to 230V..please suggest me something..
     
  6. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    Measure your dc voltage with a load on the transformer. You could be overloading the dc side, as Bill said the design isn't very good and getting 1 amp on the ac side will require several amps on the dc side. The load can be a incandescant light bulb, that'll give you an idea of how much the voltage will drop.
     
  7. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    One of several issues is you are confusing RMS (which what any meter will read) and P-P from the battery. There are ways to do this, but what are you trying to power? As inverters go this design has major issues in multiples. Without more advanced circuitry you simply will not be able to approach a sine wave, and we don't know if this is a problem or not without more input from you. It is interesting to note we are going pretty much down the same bath as the other thread, this was not one of Mr. Roon's better designs.

    Here is the other thread.

    555 timer inverter

    It even has the same title, and is very recent. Interesting.

    Basically you're going to have to come clean to get much more in the way of help. I know of ways to double the RMS voltage, as well as squeezing a lot more efficiency out of the power supply drivers, but you are dealing with high voltage (which will likely not have much in the way of power no matter what), and frankly you seem to be a bit of a beginner.

    What I think I know is you have a 12VDC power supply, you want 220VAC out. You aren't completely familiar with with the differences and relationships between P-P, RMS, and the relationship between RMS and waveforms (square and sine waves).

    What we need to be able to help is what your output load is, and the currents you expect to get out of this. This will tell us if this basic concept (the design is frankly unusable) will even come close to doing what you want. Square wave inverters are common (almost the norm), but they are noisy to electronics in the extreme. When I started with electronics they were one of the first circuits I learned.

    Have you seen these?

    Bill's Index

    The 555 Projects
     
    Last edited: Jul 8, 2010
  8. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    It is interesting to see that there is a great deal of interest in inverters from locations with unreliable power distribution.

    Among several other problems with these devices is the amazing load on a battery they cause. With a step up to 220 VAC from a 12 volt battery, you need a transformer and battery that can handle on the order of 100 amps in order to give a 5 amp capability at the output. Batteries of that capacity and transformers wound for those currents are scarce. That is for a 1000 watt output.

    That is a best-case situation, too. The output will be driven from a square wave input for minimum losses in the switching. If you need a sine wave output, the loss on the driver side becomes huge. A commercial inverter may be expensive, but is still probably cheaper than something built locally. Parts are amazingly expensive unless purchased in quantity.
     
  9. jayashree95

    Thread Starter New Member

    Jul 8, 2010
    5
    0
    load at the transformer output will be maximum of 100ma.. i want the voltage at the secondary of transformer should be 230V thats it. please suggest me improvements for the circuit which ever i have used and the same thing is attached
     
  10. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    You still haven't told us what you are going to do with it. You want help, you provide information.
     
  11. soda

    Active Member

    Dec 7, 2008
    174
    13
    This is a diagram i got from, i think Tony. Remove the secondary winding of a microwave Owen transformer and then use 10amp magnet wire and wind it 12 times on to the secondary. I didn't try it myself but why don't you.
     
  12. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    It still has the same problems. Line voltages do not use square waves. There are some applications this can work, but not many.

    It also has an added problem with frequency stability. The oscillator is also part of the power generation circuitry. Many cases this matters too. Line frequency is surprisingly accurate, somewhere around 0.1% or so.

    If we are given information we can make meaningful judgments, but not until we have facts.

    The above drawing does have one thing the other concept didn't, it was designed for high current.
     
  13. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
  14. soda

    Active Member

    Dec 7, 2008
    174
    13
    Smile, ok sgtwookie now i at least know not to use the diagram
     
Loading...