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555 IC not amplifying enough

Discussion in 'General Electronics Discussion' started by Electro132, Jun 20, 2016.

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  1. Electro132

    Electro132

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    3
    Feb 12, 2013
    Hi,

    I am doing a combined circuit involving a 9v battery, a 555 IC oscillator (with timing input of 1K + 1 nF cap, 100K pot for pulse width modulation) and a charging / discharging circuit using a 2200 uF 25V cap with a 10 ohm resistor for charging and a 100 ohm for discharging. When i measured the output of the 555 i got 2.43 - 5.03 V (using the pot) and between 134 - 173 mA. With the cap i got 191 mA for output and between 6 - 7v across the cap. When i tried to combine these two so i can amplify the output signal, it would reduce the signal to almost nothing. I would like to know how and why this is happening as i am pretty sure voltage would increase the amplification of an oscillator without altering the freq.
     

    Attached Files:

  2. Herschel Peeler

    Herschel Peeler

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    65
    Feb 21, 2016
    The 555 looks like a good circuit. I'm not sure what you are trying to accomplish with the rest of the circuit. What do you mean "amplify"?
     
  3. Electro132

    Electro132

    261
    3
    Feb 12, 2013
    Well i looked at some tutorial graphs and it showed that the higher the voltage level the more amplified it is not causing the freq to change. So i wanted to see if i could do it but i have had no luck so far. However it is also possible to change the duty cycle (which is why i have the 100K pot) but that would only mean i can change the amount of time it takes to turn on and off for the duration of the time interval. So all in all, i was having some sausages with onions and a bun earlier today when the positive line from the cap kept bugging me. I don't know but it seems that i have to find a way to connect the positive line to the 555 output to increase it from 134 - 173 mA to at least 200 mA for study purposes.
     
  4. Herschel Peeler

    Herschel Peeler

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    Feb 21, 2016
    So when the output of the 555 goes low what is supposed to happen?
     
  5. Electro132

    Electro132

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    Feb 12, 2013
    the 555 starts to charge up again and is ready for the next time interval. i looked at the op amp 741 and it seems to boost it a little which is quite disappointing as i attached the 555 output to an inverting DC amplfier, I thought it would amplify the output but it only reduced it.
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    I think the issue is that a 555 is an oscillator, not an amplifier.

    Failing to see it amplify is kinda expected.

    Perhaps what you want is not actually amplification. I have tried to understand what you actually require, but I'm not at all certain I understand.
     
  7. Herschel Peeler

    Herschel Peeler

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    65
    Feb 21, 2016
    I think what he is trying for is a strong output pulse from the discharging of the capacitor at the output, but when the output of the 555 goes low it kills that.
     
  8. Herschel Peeler

    Herschel Peeler

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    Feb 21, 2016
    Design 778 discharge pulse.PNG
    Maybe something like this for the output. I haven't tried it yet. A lot depends on what timing you want. The capacitor charges while the output of the 555 is low and discharges when the output goes high. So the 555 timing should be appropriate.
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Perhaps a statement from @Electro132 telling us what he wants to do rather than a description of how he is trying to do it would help us?
     
  10. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
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    May 8, 2012
    This really sucks. At my age my doctor wants me to have general checkups every six months. Since I hate those lectures about cutting back on alcohol and carbs I dry myself up three weeks prior to my visits. With that fact in mind I think I'd do better understanding this thread ....before I fasted! o_O:confused:

    Chris
     
  11. Electro132

    Electro132

    261
    3
    Feb 12, 2013
    HI sorry for the delay. Ok so what i am trying to do is break a wine glass using an oscillator and capacitor charge/discharge circuit but I found that an op amp was better. This should be achievable with just an oscillator and op amp. I managed to fix the oscillator's output to produce pulses, placed it into the op amp and then found out that the voltage dropped for some reason. The same with the capacitor when i pressed the button for discharging. Isn't that funny? I think i'm on the right track but i just don't understand why the op amp is producing smaller voltages than its input.

    I thought it should of been the other way. The other thing was, i was thinking the other day about whether it is the amount of the supply voltage i am putting in that's causing it since the saying goes 'you only get out what you put in'. So i'm thinking if the 555 oscillator's output is already near the equivalent of the maximum voltage being supplied then that must be the reason why the op amp's output had become smaller. So i'm guessing that if i were to reduce the 55 oscillator's output somewhat, then the op amp can 'breathe' and be able to increase. What do you guys think? I don't know, i'm just guessing here.
     
  12. AnalogKid

    AnalogKid

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    Jun 10, 2015
    First, the component values in post #1 are off by about 100-to-1. I'm surprised the chip does anything. Read the datasheet.

    Second, you have not mentioned a speaker anywhere. Without one, a 555 circuit will not shatter glass because glass is not a conductor. With one, a 555 circuit will not shatter glass because it cannot make enough energy.

    Without a schematic of the opamp circuit, no real help is possible.

    ak
     
  13. Herschel Peeler

    Herschel Peeler

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    Feb 21, 2016
    LM555 at 9 V (200 mA out) is only 1.8 Watts. What kind of power level and frequency do you think you need? Maybe120 to 150 dB at around high C? My attempts to convert dB to equivalent Watts fails me. Maybe one of these engineers here can help. My math says 120 dB comes to about 2,000 Watts.
    High C (C10) is around 16 KHz? That frequency is within the range of a tweeter, but the wattage I calculate can't be right. Better be a good tweeter to get high wattage out up there. Of course specific frequency depends on the quality of the glass.
     
    Last edited: Aug 13, 2016
  14. duke37

    duke37

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    Jan 9, 2011
    The 555 will not be able to supply much current and a 741 much less. A simple transistor or fet as an amplifier can push the current up to 1A or more.

    You probably do not need much power to shatter the glass. Chose a glass (expensive) that will ring when stroked around the rim then set the oscillator to this frequency. The amplitude should build up until the glass is overstressed. I do not think you will have any success off resonance, use a hammer instead.
    The difficulty will be to link the transducer to the glass for efficient power transfer.
     
  15. davenn

    davenn Moderator

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    Sep 5, 2009
    and addition to the above good comments, the 555 produces a square wave output, where an Osc. with a sine wave output would be more effective



    Dave
     
  16. duke37

    duke37

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    Jan 9, 2011
    A square wave has a little more fundamental than a sine wave of the same peak amplitude so should be more effective. It is also is easier to produce.

    The main problem would seem to be getting the right frequency. It may be possible to include the glass into a feedback oscillator but coupling would be difficult.

    Trevor
     
  17. davenn

    davenn Moderator

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    I strongly suggest that you are likely to get a resonant sine wave to shatter the glass long before a square wave of the same amplitude
    because the square wave is full of harmonics not directly resonant to that of the glass, therefore is lots of wasted power ;)

    sounds like a good physics experiment in the making there :)


    D
     
    Last edited: Aug 15, 2016
    CDRIVE likes this.
  18. duke37

    duke37

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    Jan 9, 2011
    I would do it if I were not shattered.:D
     
    CDRIVE and davenn like this.
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