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555's are terrible, no they're not, yes they are, no they're not

Discussion in 'General Electronics Discussion' started by Arouse1973, Dec 22, 2013.

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  1. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    edit: This thread extracted from here: https://www.electronicspoint.com/electronics-newbie-controlling-led-illumination-t266361.html

    555 timers are rubbish and should be banned any crediable engineer would not use them. You could try a constant current charging a capacitor as part of an osc circuit this gives you a linear ramp which you could pick off and use this as a pwm control. This would give you good control over the leds output. Just a thought.
    Adam
     
    Last edited by a moderator: Dec 23, 2013
  2. Six_Shooter

    Six_Shooter

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    555 timers are the basics of many electronic projects, and a great stepping stone for people new to electronics as the OP says he is. Many things can be done with that one simple IC, to disregard them them as useful or a learning tool is very poor attitude to have.

    There are about a thousand ways this project could be accomplished, timers, microcontrollers, discrete circuits (that would likely take on the form similar to a 555 in the end anyway).

    If I were doing something like this I would likely start with a microcontroller of choice (PIC, Atmel, etc.) then using PWM dim the LED in known steps and likely print this value to an LCD or an SD card with external triggers to make a record of when things are happening, such as when the patient notices a lack of light, press a button to stop the dimming or record that PWM value, which can then be converted to lumens, based on using other tools, but that's just me.
     
  3. davenn

    davenn Moderator

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    that comment gets my full support !!
    they are a fantastic little chip with 1001 uses in electronics

    Dave
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    No.

    Yes.

    Yes.
     
  5. kcoer

    kcoer

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    Lol arouse, your right. He should have bought a 100$ intel i5 chip to control these LED's. A lot more efficient then these ancient 555's. 555's have no use for modern electronically projects.
     
  6. iimagine

    iimagine

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    Oct 23, 2013
    I agree

    I disagree. People who are new to electronics should learn how basic electronic components work. Introducing 555 to them from start is a bad idea, because then, from that moment on, 555 is like a super chip to them. There is absolutely nothing great about
    555. I have seen so many ppl use these 555s to built a PWM. That is just wrong!
     
  7. davenn

    davenn Moderator

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    then you have been sadly misled :(

    Dave
     
  8. Arouse1973

    Arouse1973 Adam

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    iimagine is bang on the mark. I have mentored university student. What's the first chip they want to rule the world with. Yep 555 timer. They have no place in modern electronic design, they are fine for the hobbyist but if we teach these new guys to use them for everything then if they choose a career in electronics then they will want to use them. Many production design have failed due to the quirky nature of the reset circuitry of the timer with false triggering and weird double output pulses you get sometimes. a lot of manufactures in the car alarm industry moved away from them 20 years ago because of the problem associated with false triggering of their alarm circuits.
    Anyway this is just my opinion and no doubt many of you have reliable working circuits using them, then try and make 10,000 production units and see what happens. Just Google the issues and you see what I mean.
    Adam
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    If you're arguing that people should use appropriate hardware, then I'm with you.

    If you're arguing that a 555 is not appropriate for anything then I'm not.
     
  10. Arouse1973

    Arouse1973 Adam

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    For hobbies fine Steve, but in my opinion they shouldn't be used for production designs they can create more problems than it's worth. Please read extract from EDN.
    My apologies Chris, for not realizing there are other people in the world that think analog is fun. I will have to pass on doing a design entry, my experience with the 555 is that it is the hobbyist’s friend and the engineer’s nightmare. Indeed, having analog fun in my own curmudgeonly way, I wrote up a few 555 contests entries, several from personal experience. My contest submittals would be:
    1.Use a 555 timer for power-on-reset that you find out does not really work because the 555 is, at its heart, a digital chip, and then the entire design cannot be shipped and all the bosses hate you.
    2.Use the 555 with high-value resistors to learn that leakages change the oscillator period.
    3.Use the 555 as a one-shot that mysteriously latches up and never works if power is applied gradually.
    4.Use a 555 timer in a battery-powered product as a voltage sensor since the frequency varies with power supply voltage.
    5.Use a 555 with low-value capacitors so stray capacitance and board variance gives you an out-of-spec output frequency.
    6.Use the 555 timer as a temperature sensor, since its frequency goes all over the place depending on ambient temperature.
    7.Use a CMOS 555 to learn how input transients can latch and blow up the part.

    just a few minor issues don't you think. These problems were discovered by design engineers like myself and have learned the hard way. Guess what they stopped using them.
    Thanks
    Adam
     
  11. davenn

    davenn Moderator

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    LOL Adam, you make me laugh so much

    dont blame the chip if you are unable to impliment its use properly and using it within its limitations, like any chip has

    that's just the old saying of " a poor workman always blames his tools"

    I use the 555 in a couple of commercial products I produce and have never had any hassles. For one product, out of the some 500 out in use, there has never been a return for misoperation of a 555. Actually only 2 board failures have ever occurred, a set of 3 BC337 transistors driving an external LED display. And that was only cuz the custoner wasnt using the product within its guidelines!!

    cheers
    Dave
     
  12. Arouse1973

    Arouse1973 Adam

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    Merry Christmas Dave:)
     
  13. davenn

    davenn Moderator

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    and to u buddy :)
     
  14. brevor

    brevor

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    Last edited: Dec 24, 2013
  15. BobK

    BobK

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    Hey, I am a hobbyist hacker and I made a servo controller with a 555 30 years ago, when I knew practically nothing, and it I designed it myself, and it worked. It would have been a stretch for me at that time to do it any other way. Now, however, almost anything that could use a 555, I would use a microcontroller, but that is a different kind of obsession.

    Bob
     
    Last edited: Dec 24, 2013
  16. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
  17. Arouse1973

    Arouse1973 Adam

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    Yes agree times have changed. But some people can't manage change.
    Merry xmas Bob
     
  18. iimagine

    iimagine

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    Oct 23, 2013
    Merry Xmas to all!

    I'm not saying that 555s are bad...

    A typical 555's internal contains 2 comparators, a flip-flop and a push-pull output. What is so great about this?

    As for 1001 uses of the 555:

    1. To flash an LED, only 2 transistors and a few extra components are needed to create an extremely efficient circuit! But yet, 555s are preferred.

    2. For timing circuit, only RC and a CMOS inverter are needed to create an extremely efficient circuit! But yet, 555s are preferred.

    3. For PWM, a quad opamp/comparator IC and a few components are needed to create an extremely reliable and efficient circuit! But yet, 555s were forced.

    4. For osc...

    Just my 2 cents :)
     
  19. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    I'm quite happy to agree that there are many cases where there is a better solution to using a 555.

    What I can't accept (until you,or someone else proves it) is that there is *always* a better solution (and this is *always* in the broadest sense -- cheaper, easier, simpler, more understandable, etc.)

    Perhaps instead of being continuously negative, you can keep your eye out for each and ever y mention of the use of a 555 and simply suggest a better option.

    That would provide positive input and would benefit all of us far more than rhetoric.
     
  20. Arouse1973

    Arouse1973 Adam

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    I agree with this Steve.
    Merry xmas
    Adam
     
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