TLC555 2 Led Flasher Update

Discussion in 'General Electronics Chat' started by ShockBoy, Nov 1, 2009.

  1. ShockBoy

    Thread Starter Active Member

    Oct 27, 2009
    186
    0
    Well, here is the update for my circuit. I want to thank everyone who assisted me in my first venture. The link is to an application of the circuit. Also attached is the schematic of what finally worked for me. If anyone wants to comment on my schematic, I would appreciate it. It's running 6 LED's (2 5mm, 2 3mm and 2 2mm). I added 2 more led's- extras from a strand of halloween lights. Once again---Thanks:)
    http://s974.photobucket.com/albums/ae228/ShockBoyPB/?action=view&current=100_3411.flv
    (hopefully this link works)
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    I would recommend connecting the cathode of D1 to pin 3 of the 555 which can sink more current than the discharge pin.
     
  3. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    I'm not sure, but in this case I don't think that is true. This is a CMOS 555.
     
  4. ShockBoy

    Thread Starter Active Member

    Oct 27, 2009
    186
    0
    I had an hour and a half to wire and stuff the led's into that pumpkin. I'm happy with the results. Currently I have 8 LED's going with no major dimming.
     
  5. ShockBoy

    Thread Starter Active Member

    Oct 27, 2009
    186
    0
    mik3, is that why D2 was significantlly dimmer with the 470 resistor I originally had, before the 33?
     
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    It's because the TLC555 can only source about 10mA when Vcc=15v. You've reduced the resistor attempting to compensate for the 555's poor current sourcing capacity.

    If you'd gone with the circuit I suggested that had the 2sc1813 transistor with 6.8k on the base, it should've worked just fine.
     
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