NE555 Timers

Discussion in 'General Electronics Chat' started by MusicTech, Apr 4, 2008.

  1. MusicTech

    Thread Starter Active Member

    Apr 4, 2008
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    Hello, I am new here, and even newer to electronics.

    I really need some help catching up to where I want to be, I have a big question that will probably be easy for most, if not all of you.

    I am big into music technology (hence my sn) and I have been looking all over for a good definition of an ne555 timer, as they are used frequently. Everything I have found has either been way over my head or really geared towards a layman who has no interest in electronics, but ust wants a basic idea of what an ne555 is. So, with all that aside, can someone please explain to me, from easy terms to intermediate, to even very complex, what an ne555 does exactly, (I mean it's kind of abovious it times things, but how) and how to work, and practically, how it affects sound when working with AC and other sound waves.
     
  2. Wendy

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    Mar 24, 2008
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    A 555 has all the componts built into it to either a> make a monostable pulse, in other words, a pulse of specific length from a trigger, or b> make a very stable ocsillator or tone generator. With very few parts it can make a tone generator that isn't quite so stable, but very simple. Since it's output is basically digitial it is also great for digital projects of all types. It can also flash LEDs in several different ways, in either mode.

    With a little more circuitry it can be a function generator, modulate a square wave with something like audio, demodulate, and more. It has the right mix of parts to be very useful.
     
  3. mik3

    Senior Member

    Feb 4, 2008
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    Check this websites:

    http://www.uoguelph.ca/~antoon/gadgets/555/555.html

    http://www.tel.uva.es/personales/tri/tutorial.htm

    or type 555 tutorials or just 555 in google to find more
     
  4. MusicTech

    Thread Starter Active Member

    Apr 4, 2008
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    Yeah, I hear that some of those words thrown around a lot, what is a trigger exactly in this context, and what do you mean by a specific length from, like certain number of waves away from what.

    Also how does it actually modulate, and what is a function generator.

    I am sorry to sound so basic, but I admit I can be very slow on picking things up at times.

    How expensive are they if you buy them at, not mass but.. enough like 20 or so. Do you think the best thing to do is take one apart and do some analysis by myself. Or would you say that they are based too much on a nanoscale? (I assume they are, I know how tiny they are, especially considering al the components inside.)
     
  5. MusicTech

    Thread Starter Active Member

    Apr 4, 2008
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    oh, and thank you for the websites, they weren't there as I was typing
     
  6. mik3

    Senior Member

    Feb 4, 2008
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    You have to spend hours searching the internet to find something you like. I spent lots of hours studying in the internet to achieve the level of knowledge on electronics i have now.
     
  7. MusicTech

    Thread Starter Active Member

    Apr 4, 2008
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    I believe you. I know what it's like spending hours seemingly finding nothing. It's funny because usually it's only one sentence that takes hours and days and weeks of research all come together and make sense, at least that's what I find.
     
  8. Wendy

    Moderator

    Mar 24, 2008
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    A function generator is something a musician might appriciate, it makes waveforms of differing shapes. This affect the sound of the note being played even though they are on the same key. For example, square waves (555 staple waveform) has been compared to bagpipes.

    Lets say you wanted to have a light stay on for 1 minute after you push the button, the button is the trigger, and the 555 is the timer.
     
  9. MusicTech

    Thread Starter Active Member

    Apr 4, 2008
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    But, I am sure, having knowledge of programming there isn't a little switch that you set to 1 minute and that's that. so how would you tell it to stay on for one minute. If this is a ridiculously long answer and you don't want to explain, I understand.
     
  10. Wendy

    Moderator

    Mar 24, 2008
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    Circuits aren't programed unless their digital, then not in most cases. A 555 is designed with it's components for what you want. Take this circuit...

    [​IMG]

    You'll note the equation below. It will tell you what the circuit will do for particular values. In the case of musical notes, I'm sure you could find a chart somewhere that would match a frequency to a note.

    Math is the cornerstone of electronics.

    I fudged on those circuits, and put in a variable resistor, which allows the user to change the note (or flash rate) to whatever they want.

    The real key to understanding electronics is reading. The eBook here at this site isn't finished, but the basics are all there.
     
  11. MusicTech

    Thread Starter Active Member

    Apr 4, 2008
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    So, if I understand correctly, you buy a timer, already having knowledge of how long it times for. So you could even get a timer that functions as "on" indefinitely, that is until it is pressed again. I don't know if you are interested, but here's a site for the musical values:

    http://www.intmath.com/Trigonometric-graphs/music.php

    basically 440*2^(n/12) whereas n is one half step above or below A440. You have probably at very least dabbled in music at one point in your career to help you appreciate this, but st in case not, there are the 12 half steps accepted in our Western music per octave, and then judging by that equation, that 13th note, 12 above the last will raise 2 to the 1, which of course will double 440. i am sorry, that was a bit ridiculous, I am sure without a doubt you know how to use exponents... I am good at math, but I know you are exponentially better, pardon the pun
     
  12. Wendy

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    About the math, you might be surprised. I am a tradesman, I know what I need to know.

    A timer times, if it is on forever then it isn't timing very well. :D

    There are other circuits and chips that will toggle on a button press. But I think you're getting the idea. It is the component you connect outside the chip, and how you connect them, that dictates function.
     
  13. SgtWookie

    Expert

    Jul 17, 2007
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    It might help you to look at some datasheets for various 555 timers. There are block diagrams of how they function internally.

    Note that there are many different "flavors" of 555-type timers. The basic two types are bipolar and CMOS. The bipolar versions can source (output) or sink (act as ground) for up to 200mA of current. The CMOS versions are far more limited in their output current, but are very useful in battery-powered devices. There are also some very low-powered CMOS versions like the TLC555. They are far more power-economical than even the standard CMOS versions, but as a result are very limited as to how much current they can source or sink.

    A 556 is a dual 555.
    A 558 is a quad 555. You don't see a lot of these being used, but could be quite useful for creating sound effects.
     
  14. MusicTech

    Thread Starter Active Member

    Apr 4, 2008
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    hmm very interesting... so can you get a ne555 that outputs DC? I mean if you were to light an LED with AC, wouldn't it flicker really really fast, unless you're using something ridiculously slow of course.
     
  15. Wendy

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    Mar 24, 2008
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    If the rate of change was once every 2 seconds, then it wouldn't flicker. The schematic I posted with 2 LEDs was just such a circuit. The 555 has a max freq of about 200Khz, but the low end is up to the designer.
     
  16. SgtWookie

    Expert

    Jul 17, 2007
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    One of the reasons the 555 has been so popular is the extremely broad range of output times. You can even cascade them to get VERY long delays (days, even) - however, the accuracy suffers with really long or really short delays due to fluctuations in the power supply and things like capacitor leakage, parasitic inductance, and other phenomena. If you keep your timing limits for a single 555 somewhere between an hour and 100kHz, it's unlikely you'll run into those kinds of things.
     
  17. MusicTech

    Thread Starter Active Member

    Apr 4, 2008
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    ok, thanks for the tip
     
  18. tronics

    Member

    Apr 16, 2008
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    ok ilove 555,s and there are 100,s of uses. i will give you the 3 main uses in basic terms.

    1. ASTABLE-to give aoutput square wave at a frequency of choice, ie a 5khz square wave signal

    2. MONOSTABLE-to give a high out when triggerd for a set time,ie you hit a switch and it gives a flat dc voltage out for 1 millisecond or up to 2 hours,set by resisotrs and caps.

    3. BISTABLE- This is called a JK flip flop, the output is high or low and changes when the input is triggering it.

    hope this helps
     
  19. MusicTech

    Thread Starter Active Member

    Apr 4, 2008
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    it does. indeed. Have you done any of these projects?
     
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