Connect with us

LED and 555 timer help

Discussion in 'LEDs and Optoelectronics' started by neshx, Dec 11, 2013.

Thread Status:
Not open for further replies.
Scroll to continue with content
  1. neshx

    neshx

    5
    0
    Dec 11, 2013
    hello i am a newbie to electronics, am trying to build an Led sign for Christmas incorporating blinking and steady led lighting from ac mains....so far have been able to make the leds light steadily...however am stuck with the 555 timer... i do not have an electronics background hence little comprehension on values and voltage calculation..i have attached a picture of my circuit:(
     
  2. BobK

    BobK

    7,682
    1,686
    Jan 5, 2010
    They must be UV or infrared LEDs, because I don't see anything :)

    Bob
     
  3. neshx

    neshx

    5
    0
    Dec 11, 2013
    hehe am unable to upload the picture of my circuit...perhaps i can explain...
    i have connected the circuit to ac mains 240ac standard i think. the an ac capacitor. no resistor just the capacitor..i have received a shock but it aint lethal..next i have a bridge rectifier with a 1uf 50v electrolytic capacitor to smooth-en the dc current...i had tried a 330uf 25v capacitor but the leds indicated very little current going thru...with the 1uf 50v it works fine....next i have about 50 LEDs which light fine...nex i have a 555timer...i have read the 555timer uses around 12v so i figured by the time the voltage passes through the 50 LEDs it will have reduced to work the 555 timer.. the negative outlet of the LEDs in series i have connected as the positive of the 555 timer...with 1k resistors between pin 8 and 7 and 7 and 6. between 1 and 2 i have connected the 330uf 25v capacitor as well as the 1uf 50v capacitor but non work...(not at the same time)....the output 3 i have connected to positive side of another set of leds i want to blink....the negative of these leds is connected to pin 1 which is also connected to negative of bridge rectifier.....what i accomplish is making the first bunch of LEDs to light....any help in making them blink pleeeeeaaassssee
     
    Last edited: Dec 11, 2013
  4. davenn

    davenn Moderator

    13,589
    1,872
    Sep 5, 2009
    yes use a proper mains to low voltage DC plugpack so that you dont electrocute yourself or some one else

    you cannot pass the voltage through the LEDs before the timer chip
    as the timer chip must be able to control the LEDs

    Dave
     
  5. neshx

    neshx

    5
    0
    Dec 11, 2013
    i dont have access to a low voltage dc plugpack...am trying to make a simple sign for Christmas plus am gonna hang it so no one will be in danger of electrocution. that said if i introduce the chip immediately after the dc is rectified will it blink?
     
  6. BobK

    BobK

    7,682
    1,686
    Jan 5, 2010
    The 555 chip cannot switch mains circuits by itself.

    Bob
     
  7. neshx

    neshx

    5
    0
    Dec 11, 2013
    @bob not directly to mains....it is already direct current after rectification...any way i can lower the voltage to make the chip work...
     
  8. duke37

    duke37

    5,361
    768
    Jan 9, 2011
    Rectification from the mains will not reduce the chance of death.

    If you cannot find a safe low voltage supply, then you should not do it.
    As an alternative to a plugpack, you could use a USB supply or an old style battery charger if you want a lot of current.

    You have been bitten once and survived, you may not be so lucky second time around.
     
  9. neshx

    neshx

    5
    0
    Dec 11, 2013
    @duke37 actually am used to it...just a nasty bite... today got electrocuted 5 times thrice by ac mains and twice by the discharging ac capacitor...thats besides the point i just want the 555 timer to work...alternatively am thinking of disassembling a 6v phone charger to connect to the timer
     
  10. davenn

    davenn Moderator

    13,589
    1,872
    Sep 5, 2009
    if you were electrocuted, you would be dead
    you got an electric shock

    sounds like this is the last thing you should be playing with, you obviously don't have the skills or knowledge to play with this stuff

    thread lock for safety reasons
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Thread Status:
Not open for further replies.
Electronics Point Logo
Continue to site
Quote of the day

-