Learned Something New Today

Discussion in 'General Electronics Chat' started by Metalmann, Sep 14, 2013.

  1. Metalmann

    Thread Starter Active Member

    Dec 8, 2012
    Found this statement today,:

    "The 555 is not suited for battery applications and it is not really suited for combining with some types of CMOS circuitry. The 555 is a very noisy chip and has a very nasty internal feature called "crow-bar effect" that can put a lot of noise on the power rails of a circuit."

    I thought the 555 was good for almost all circuits?:confused:

    Even battery circuits?

    Link to statement:

    Last edited: Sep 14, 2013
  2. wayneh


    Sep 9, 2010
    Your link is inaccurate and pulls up ads. Not cool.
  3. DerStrom8

    Well-Known Member

    Feb 20, 2011
    Well THERE'S your problem! It's talkingelectronics! Remember colin55? The idiotic dimwit who used to visit this forum and spread his bile and filth among younger, naive members who didn't know better than to believe him? That's his site. IGNORE IT! Most of the stuff on that site is total crap, and is not to be trusted. Same with his rubbish here on the forum (and over at ETO).
    Last edited: Sep 14, 2013
    PackratKing, strantor and shortbus like this.
  4. strantor

    AAC Fanatic!

    Oct 3, 2010
    I only had a small exposure to Colin during the brief period that I frequented ETO, but I was there long enough to come away with the opinion that he is a bag of douche.
  5. DerStrom8

    Well-Known Member

    Feb 20, 2011
    Indeed, and he seems to be long gone. At the time I left, he hadn't posted for several months, if not a year.
  6. MrChips


    Oct 2, 2009
    There is some truth to that.
    Replace your NE555 circuits with TLC555 or LMC555 if you wish lower power consumption and less noise on the power supply.
    #12 likes this.
  7. ronv

    AAC Fanatic!

    Nov 12, 2008
    I didn't see the exact article, but the 555 has a totem pole output that draws a lot of current when it switches. I suppose this is worse if say you are using a 9 volt battery with high internal resistance. Most of the datasheets recommend decoupling the supply close to the device.
    Yes, he does get some strange ones.
  8. mbohuntr

    Senior Member

    Apr 6, 2009
    I'm not sure about noise, but I have been having more success using diodes on the output since I discovered they can sink current as well as source it. This seems to take out some of the glitches from my circuits...
    PackratKing and #12 like this.
  9. #12


    Nov 30, 2010
    Oops. I spelled that with 2 L's. Fixing list...
  10. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    The same principles apply to TTL circuits. I wonder if the person mentioned recommends not using TTL with battery power for the same reasons.
  11. ian field

    AAC Fanatic!

    Oct 27, 2012
    This doesn't happen with the CMOS 555, but its O/P drive capability doesn't hold a candle to the bipolar part.
  12. bountyhunter

    Well-Known Member

    Sep 7, 2009
    I remember building an alarm circuit with a 555 which would cycle on and off when tripped. I breadboarded in my lab (bedroom) and was watching my little B+W TV which used a rabbit ear antenna:

    Each time the 555 switched states, the picture on the TV would completely fuzz out. They can make some serious noise unless well decoupled.