🚀 go-pugleaf

In article <1992Nov3.094923.44351@kuhub.cc.ukans.edu>, heacock@kuhub.cc.ukans.edu (Doug Heacock) writes:
|> I'm putting together a quick-and-dirty circuit that will light 10
|> LED's in sequence, one after the other.  Here's my idea so far:  I
|> intend to use half of a 4011 (quad 2-input NAND gate) as a clock
|> oscillator to drive half of a 4518 (dual synchronous up counter),
|> which will in turn drive a 4028 (BCD-to-decimal decoder), which will
|> actually drive the LED's.  I was thinking I could connect all of the
|> LED cathodes to ground through a single 330-ohm resistor, since only
|> one would be lit at a time.
|> 
|> Does this sound workable?  I welcome more elegant solutions--these
|> chips just happen to be the ones I have on hand at the moment.
|> +-----------------------------------------------------------------+
|> | Doug Heacock, Academic Computing   | heacock@kuhub.cc.ukans.edu |
|> | Services, The University of Kansas | heacock@ukanvax.bitnet     |
|> | Lawrence, KS 66045                 | Amateur radio: N0NZQ       |
|> +-----------------------------------------------------------------+

Use a 4017 decade counter. One chip solution (plus maybe a couple of
inverters/NAND gates for the oscillator).

Note that you should use Schmitt input gates for making RC oscillators - current
is minimised and the output will be cleaner, with a faster risetime.

Actually, a 74HC4017 is capable of driving a high-efficiency LED directly (keep
the current under 5mA or so). Yes, you can common-cathode the LEDs in this
application.

JohnH

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