Christmas Display

Discussion in 'The Projects Forum' started by k7elp60, Dec 2, 2011.

  1. k7elp60

    Thread Starter Senior Member

    Nov 4, 2008
    478
    69
    I was looking thru may parts to make a Christmas display with the maximum number of LED's and minimum # of parts. The attached circuit uses three quad 2 input nand schmitt triggers(CD4093) and one 1 of 8 switch (CD4051). The neat part is it only uses one external resistor as current limiting resistor for 8 to 24 LED's. If a 9v battery is used and the Vf of the LED's totals near 8V then no resistor is needed as the internal 100 resistance of the CD4051 does the current limiting.
    Caution the maximum LED current should not exceed 25mA.
    Ned
     
    Last edited: Dec 2, 2011
  2. sheldons

    Well-Known Member

    Oct 26, 2011
    616
    101
    not very economical use of your 4093 gates here...you only need one gate ,one cap and one resistor and you have an osc....so you could use one 4093 with one unused gate spare but its quite an interesting way to use that ic
     
  3. k7elp60

    Thread Starter Senior Member

    Nov 4, 2008
    478
    69
    Yes you are so right. I get to eliminate one of the CD4093's.
    Thanks for you input sheldons. I'll redraw the schematic.
     
    Last edited: Dec 2, 2011
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