Hello need some help with timer and 24v

Discussion in 'The Projects Forum' started by rastaman46, Dec 4, 2011.

  1. rastaman46

    Thread Starter Member

    Nov 17, 2011
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    Hello need some help with timer and 24v

    Im got 100 leds in parallel its based on 24v MAX:8VA

    Im inserted new ultra bright leds and they works but im try switch it on 12v true ne555 to make them flashing and im end with 4 leds on.

    How to do to make all 100leds flashing true timer ???
     
  2. tommydyhr

    Active Member

    Feb 3, 2009
    39
    4
    Please provide a schematic, describing how you've hooked up the diodes to the 555.
     
  3. sheldons

    Active Member

    Oct 26, 2011
    616
    101
    You may need a better output stage to use with your 555 heres an example...show us how you have connected them
     
    Last edited: Dec 4, 2011
  4. rastaman46

    Thread Starter Member

    Nov 17, 2011
    69
    0
    circuit use

    [​IMG]

    Instead of 100k im use 1k
    instead of c1 1UF im use 1000uf (make it flash nice slow)
    no switch in it

    but rest is the same
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    Since you are not using the switch, you don't need R1/R2.
    That means you can leave R3 at 100k, and just increase C1 to 10uF; you will use less power that way, and the timing will be the same.

    Here, have a look at the attached. I've added a 12v regulator with input and output caps, and a power MOSFET to turn the LEDs on and off. The 2N3904 has a limited current sink capacity; perhaps 100mA if you have 10mA flowing through the base. A power MOSFET is a voltage controlled device; it is being used as a switch here. The MOSFET shown can sink several amperes worth of current.

    I just threw some LEDs wired in strings with resistors to give you the general idea how that would work. The number of LEDs you can use in series and the resistor you will need will depend on the specifications of the LEDs that you are using.
     
  6. rastaman46

    Thread Starter Member

    Nov 17, 2011
    69
    0
    Hi thanks for circuit.

    Got my parts delivered all works nice thanks for that.

    Any chance to do like 3 options on circuit "Fast-slower-very slow" say intervals is 30-40 seconds?
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    You're getting about 1-1/2 seconds now, right?

    If you replace C3 with a 220uF capacitor, you'll get about a 35 second interval.

    Alternatively, you could replace C3 with a 100uF cap, and R1 with a 220k Ohm resistor to get roughly 35 seconds.
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    You didn't mention what flash rates you wanted besides the 35 to 40 second rate.

    If you want it to be easily adjustable, try replacing C3 with a 100uF capacitor, and replace R1 with a 200k pot in series with a 22k resistor.
     
  9. rastaman46

    Thread Starter Member

    Nov 17, 2011
    69
    0
    im playing with C3 just for speed now im got 1uf on its flash quick 10uf bit slower 47uf more slower as bigger its its at slower it works dont you? .

    But im want to make it flash quick for 30s than flash slower for 30s that back to fast flash again.

    if you know what im meant (circuit change its speed it self every 30s or so)
     
  10. SgtWookie

    Expert

    Jul 17, 2007
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    Oh, I see - well in that case, you will need another timer circuit just like the 1st one (U1, C3, R1, M1) - but for this new part of the circuit, you will need to change C3 to 100uF, R1 to 430k Ohms. That will give you about 30 seconds on, and 30 seconds off.

    M1 will then connect the ground of an additional capacitor that is connected in parallel to the original C1.

    Have a look at the attached. The green trace is the output of the left 555 timer; ~30 seconds high, ~30 seconds low.
    The cyan trace is the output of the right-hand 555 timer, showing the flash rate.
     
  11. rastaman46

    Thread Starter Member

    Nov 17, 2011
    69
    0
    thanks again

    but any chance to use something different instead of 430k?

    got all parts except 430k to get it it take 2-4 days.
     
  12. SgtWookie

    Expert

    Jul 17, 2007
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    You could probably get away with using four 100k resistors in series.
     
  13. rastaman46

    Thread Starter Member

    Nov 17, 2011
    69
    0
    Thanks for your big help

    but now im got problem im test circuit on DC adapter witch was 21V

    im plugged old adapter back and circuit dont work because adapter is AC/AC.

    Did any chance to get it working on that AC/AC adapter or i need DC one?
     
  14. SgtWookie

    Expert

    Jul 17, 2007
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    You said it was 24v? :confused:

    The circuit requires DC in order to function. You may have damaged or destroyed it by connecting it to AC.
     
  15. rastaman46

    Thread Starter Member

    Nov 17, 2011
    69
    0
    Im test it on 21v one problem im had was half lights was not on (once im done and test circuit im try on my old adopter just for 2sec or so did not work )

    Than im spouted what my old adapter is AC

    No circuit works if its on DC but dont work on AC

    sorry for my bad skills
     
  16. Wendy

    Moderator

    Mar 24, 2008
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  17. SgtWookie

    Expert

    Jul 17, 2007
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    I edited what you wrote, into what I believe that you meant to write.
    If I made an error in my corrections, please tell me where I am not correct.

    If you built the circuit like the 2nd schematic I posted, then the LED strings that are not lit either have one or more bad LEDs in the string, or the connections are poorly made, or one or more of the LEDs are installed backwards. The anode must be towards +21v, and the cathode must be towards the 21v return (-21v).

    The circuit was not designed to work on AC. You would have to add a bridge rectifier, filter capacitors, and a regulator in order to be able to use AC input from a transformer. It is cheaper and easier to just get a "wall wart" plug-type DC power supply.
     
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