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Timer 555 voltage

Discussion in 'General Electronics Discussion' started by colum, Apr 28, 2020.

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  1. colum

    colum

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    4
    Jul 25, 2013
    I want to apply two 9 volt batteries to a 555 timer supply to make 18 volts but according to instructions a 555 timer calls for 15 volts max..Other than using one battery for the timer..What is the best way to reduce the voltage to less than 15...Thanks....colum
     
  2. bertus

    bertus Moderator

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    655
    Nov 8, 2019
    Hello,

    What do you have in mind?
    Why do you need 18 Volts?
    The NE555 will also work on 9 Volts.
    When you want to reduce the voltage from 18 Volts to 15 Volts , you could use a LM7815.

    Bertus
     
  3. Alec_t

    Alec_t

    2,939
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    Jul 7, 2015
    It's not good practice to run components at their maximum rated voltage if you want them to have a long and happy life, so why use 15V?
     
  4. Audioguru

    Audioguru

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    698
    Sep 24, 2016
    Two 9V batteries will quickly drop the voltage too low for an LM7815 voltage regulator to work. Then the voltage keeps dropping.
     
  5. colum

    colum

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    4
    Jul 25, 2013
    Thanks for the replies..As advised I will use one battery for the 555 and an other supply for the rest of the circuit..colum
     
  6. Bluejets

    Bluejets

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    Oct 5, 2014
    You could use the one battery and a buck converter but you still have not said why you need the high voltage.
     
  7. colum

    colum

    155
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    Jul 25, 2013
    Thanks Bluejets..I want to drive a transistor with a higher voltage output independently of the 555 ct
    I like to experiment and it really doesn't bother me if I fail I just try again.
    I do appreciate help from these forums otherwise there would be far more fails and with Radio Shack gone parts are much harder to get...Thanks...colum
     
  8. bertus

    bertus Moderator

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    Nov 8, 2019
    Hello,

    Can you post a schematic of your project?
    That way we can see if we can make improvements on it.

    Bertus
     
  9. Audioguru

    Audioguru

    3,132
    698
    Sep 24, 2016
    When I order electronic parts from Digikey or Newark before 8:00PM, they are delivered to me the next morning and I am in a different country from them.
     
    hevans1944 likes this.
  10. Martaine2005

    Martaine2005

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    May 12, 2015
    Same here, my parts arrive by 10am two months later:p
     
  11. Audioguru

    Audioguru

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    Sep 24, 2016
    2 months delivery time? Which planet are you on?
    Oh. You buy cheap fake parts from China?
     
  12. WHONOES

    WHONOES

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    May 20, 2017
    I buy bits form Farnell, RS Components and Mouser. No problems with any of them.
     
  13. bertus

    bertus Moderator

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    Nov 8, 2019
  14. WHONOES

    WHONOES

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    May 20, 2017
    Indeed it is. I think Mouser are American and have a UK base.
     
  15. PETERDECO

    PETERDECO

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    Dec 19, 2019
  16. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    Jeff, you can connect two 9V batteries in series and share a common connection, with the 555 operating from one of them and your transistor operating from the two of them. This can be extended as far as you want to go by adding more batteries in series, but I would recommend not using more than, say, six 9V batteries in series because of the electrical shock hazard during experimenting. You don't need to ask me how I know this.:oops:
     
    Last edited: May 3, 2020
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