timer for 555

Discussion in 'The Projects Forum' started by lotusmoon, Jul 14, 2013.

  1. lotusmoon

    Thread Starter Member

    Jun 14, 2013
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    I am making a 555 circuit for an LED cluster. I now also want to put in a timer which would turn it off after a certain periods of time. I wanted to be able to select 60, 90 120, 150 or 180 seconds and then it turns off. then have a manual switch to turn it back on.
    Is there a standard way of doing this
    I thought It might be possible to use another 555 circuit and connect to the first circuit with a transistor. could someone let me know if this is possible or if there is another a more simple way of doing this.
     
  2. Ramussons

    Active Member

    May 3, 2013
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  3. donpetru

    Active Member

    Nov 14, 2008
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  4. lotusmoon

    Thread Starter Member

    Jun 14, 2013
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    thank you for this and your kind offer.
    I am thinking of moving onto this at some stage.
    I took a quick look at the info it looks complicated but I guess once you start looking in to it starts making sense.
    Excuse me for being a total novice but can it produce a pulse ranging from 1hz to 20khz?
     
  5. donpetru

    Active Member

    Nov 14, 2008
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    You want to have a square wave output in the 1Hz .... 20KHz and want to know if you can this with a microcontroller? The answer is yes and no, depends on the steps, you want 1Hz step or more than 1Hz ?
    If step is 1Hz then it's best you use "microcontroller - signal generator", for example: atmega168 + AD5930 or atmega168 + MCP4921.
     
  6. Wendy

    Moderator

    Mar 24, 2008
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  7. Brownout

    Well-Known Member

    Jan 10, 2012
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    Connect the output of your 2nd 555 to the reset pin of your current one. Done in 15 minutes, no software to write.
     
  8. lotusmoon

    Thread Starter Member

    Jun 14, 2013
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    thank you for your feed back and ideas. There is so many interesting paths and journeys in this field, and so many helpful people. Thank you It lifts my heart.
     
  9. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    I'm sure you could do it with a 556 timer (dual 555). Use the reset pin on one of them, as brownout suggested, and you should be all set. If you are wanting to go into microcontrollers though, this would be a great first project. Choice is yours :)

    Regards,
    Matt
     
  10. lotusmoon

    Thread Starter Member

    Jun 14, 2013
    203
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    Thank you for this suggestion I will look at the 556 and I think I am going to try building both a 555 circuit and a micro controller circuit as I am enjoying this project.
     
  11. lotusmoon

    Thread Starter Member

    Jun 14, 2013
    203
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    I have been reading up on microcontrollers and would definately like to try and build this project first with a 555 and then also with a micro controller. I would like to find material that i could learn how to do this with a microcontroller. the project is to build a LED flasher with some different frequencies to choose from and some different times lengths to choose from. At this time I have just read generally about micro controller, and know little about code and how it is all put together.
     
  12. WBahn

    Moderator

    Mar 31, 2012
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    Pick one and focus on it. Then, if you want, switch to the other and focus on it.

    It is probably time to get more explicit on your "User Experience" description. How do you envision people interacting with this thing. From what you've said so far, and reading between the lines, it might be something like this:

    Primary User: A person that wants to see whatever the LED cluster is displaying. They push a button to activate the display and it works for a certain amount of time and then shuts off until someone pushes the button again.

    Secondary User: A person that sets up the display. They set a switch of some kind to select one of five a timeout duration from 60s to 180s in 30s increments.

    What this leaves unfinished is how the control unit interfaces to the display. Does it actually control the LED cluster to generate the display or does it just provide power to it? Or does it just provide a logic signal to enable/disable the display.
     
  13. lotusmoon

    Thread Starter Member

    Jun 14, 2013
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    What I am think of is there is a selection of frequencies available say 1hz 5, 10, 20, 30, 40hz and way of selecting one of these.
    and then a selection of times available 30 seconds, 60,90,120, 150 seconds, and a way of selecting one of these.
    so the leds can run at 10hz for 90 seconds or 5hz for 60 seconds or any combination of these frequencies and times.
    doing this from a 555 the power and signal can come from the 555 chip. I am unsure how it would work from microcontroller.
     
  14. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    The 555 isn't very accurate and will drift.

    Since you're using PICs if you have any 18F install Swordfish BASIC SE or XC8 both excellent compilers. Swordfish is very easy to learn.
     
  15. lotusmoon

    Thread Starter Member

    Jun 14, 2013
    203
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    Thank you I have downloaded Swordfish BASIC SE and looked through the web site. Is there some basic things I can get to start on my project, I am total new in this area and need to learn to write the code and find which microcontrollers to use.
     
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