Double Flash Strobe Effect

Discussion in 'The Projects Forum' started by jaxx709, Sep 9, 2013.

  1. jaxx709

    Thread Starter New Member

    Sep 9, 2013
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    Hello to all. Go easy on me its my first time both on here and creating circuits.

    I am currently building a model that calls for some very specific lighting effects. No 1 - I need a circuit to control just a few LED's (4 to 6) to produce a 100ms Double flash strobe with a 1 second delay. My investigations so far suggest only a programmed PIC chip could achieve this. Is this correct?

    No 2 - I need 2 red LED's to increase and decrease in brightness every 1 to 2 seconds. Just a nice glow without turning off altogether.

    Any suggestions would be greatly appreciated as I want to plan out before assembly and painting so I don't get stuck later.

    Cheers
     
  2. elec_mech

    Senior Member

    Nov 12, 2008
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    I believe you can do this with two 555 ICs. One set as astable with a 1Hz frequency and the other as monostable with a 0.1s time. The astable would trigger the monostable. Check out this site for more info.

    As for the glowing, check out Bill Marsden's blog, specifically the section about throbbing and fading LEDs.
     
  3. ronv

    AAC Fanatic!

    Nov 12, 2008
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    Not sure I understand this to well. Do you mean 100 ms flash, wait 1 second then flash again for 100 ms. Or flash for 100 ms some delay flash again?
    It would be less hardware (logic) with a PIC, but it could be done in logic - I think. ;)

    Give us an idea how big the LEDs are and what you plan to use for power. Can you read a schematic and solder?

    [/quote]
     
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    There are multiple strobes in a bottle, if it works: You Tube, Susan Kunkel, video , ship behind bottle. Uses 4060 and gates.
     
  5. ScottWang

    Moderator

    Aug 23, 2012
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    For using the pic, if you can do that by yourself or someone could do it for you, then it is a good way.
    I'm not exactly understand what your require, but maybe using 74HC14 and CD4017 can do the job, using 74HC14 to generate the frequency and delay, it also can replace the NE555.
     
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  6. jaxx709

    Thread Starter New Member

    Sep 9, 2013
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    To clarify I am building Star Trek Into Darkness Enterprise 1:500 model. Double flash strobe is for navigation lights. There are lots of example you tube videos for this or just wack on one of the earlier films to see what I mean. Prob only need 4 x 3mm leds all to flash at the same time. Flash flash pause flash flash pause...bout once a sec.

    The fading led is for the impulse engines. I have seen some example circuit diagrams thanks to Elec_mec. The strobe one is the one I don't currently have an exact bead on.

    To answer other questions I can solder and work at Maplin electronics so I understands some basic principles, symbols and values in order to identify. Just a lack of practical experience.
     
  7. jaxx709

    Thread Starter New Member

    Sep 9, 2013
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    9 to 12v dc PSU for supply.
     
  8. djsfantasi

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    Apr 11, 2010
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    I was going to also suggest Scott's solution. The sequence would be 0 goes to Led, 1 is disconnected, 2 goes to Led (for flash - flash) 3 & 4 disconnected (for pause) and then repeat. If you need longer pauses, you could daisy chain multiple 4017 ICs and possibly reset the count at the desired end of sequence.
     
  9. MrChips

    Moderator

    Oct 2, 2009
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    For fading, play around with two 555 timer outputs feeding into an XOR gate.
     
  10. jaxx709

    Thread Starter New Member

    Sep 9, 2013
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    Ok I think i get what u mean djsfantasi with your suggestion of the 4017. I'm wondering if anyone can send me a rough example diagram to get me started as I seem to understand that better. I'm currently working on a circuit design that involves a 555 and a 4017 to give me sequential LED flash for the warp engines.

    Also can anyone suggest a computer program that I can use to create a circuit and then simulate it so I can be sure that A) it works and B) its giving me the desired affect.

    Many thanks to all for your continued help. Sorry i'm such a noob!
     
  11. djsfantasi

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    Apr 11, 2010
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    How long do you want the flashes to last and how long should the pause between them last? Finally, how long should the pause be?
     
  12. jaxx709

    Thread Starter New Member

    Sep 9, 2013
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    Split second. I think its 100th /sec followed by at least 1 to 2 second delay.
     
  13. djsfantasi

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    Ok let me think on that.
     
  14. wayneh

    Expert

    Sep 9, 2010
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    A pulse that short can be accomplished with an RC tank. The cap can charge thru the LED and R on the positive pulse, and then discharges thru another resistor during the off period. You pick R to limit the max current and then you can control the length of the pulse - the perceived brightness - by changing C. Works great to give a "flash" effect.

    I posted an example here. Look at the "3" output of the 4017.
     
    Last edited: Sep 10, 2013
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  15. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Did you look at the lightning flashes in post #4? the flashes are 4- 43 ms on, & 3 43 ms off spaces, just to give an idea of flash apperance.
    Here is a 4060 version, I mis read second note on pulse width, thought you wanted 100 ms pulses.
     
  16. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    http://forum.allaboutcircuits.com/blog.php?bt=684

    Here is a link to Bill Marsden's blog. The Knight Rider circuit can be used without all LEDs connected. Fed with a 10Hz 555 clock, you'd get the LEDs flashing for 100ms. Connect them only to two outputs separated by one output. Ie outputs 1 and 3. The remaining unused outputs provide your pauses.
     
  17. jaxx709

    Thread Starter New Member

    Sep 9, 2013
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    Thank you all. I now have lots to think about. Unfortunately I cant seem to find any working circuit simulation software so come pay day I'm going component shopping. Will probably have more questions then.
     
  18. geko

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    Sep 18, 2008
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  19. Bernard

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    Aug 7, 2008
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    1 slip-ups on post # 15, with 10 Hx clock , delay would be 32 clocks or 3.2 s; for 1.6 s, move reset to pin 6 & eleminate D1. 50 ms would be a nice pulse.
    Outline using 4017: Using U1 & U2 only, pulse burst is separated by only 7/10 s, but U4 allows independent control of pulse width & delay. A seperate square wave osc is needed for pulsing, U5. Making R4 variable allows amplitude of pilsing to be varied. R5 allows adjsstment of minimu LED light, so that it never goes completely dark
    MPSA14 gives high inputZ & has no bothersom shunting internal Rs.
    Timing diagram shows 33 ms pulse, instead of 100 ms. 9V or 12V is fine.
    I only use eyeball simulations or breadboard.
     
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