Re: 20 LED Chaser

Rich Grise wrote:
On Fri, 31 Oct 2008 08:18:35 +0000, IanW wrote:

Sorry I should have been more specific, I meant I assembled the 10 LED
chaser that I posted previously about:

http://www.free-circuit-diagrams.com/light-led/page-1/169/led-chaser

and it doesn't work properly.


It shouldn't. According to the data ***, the 4017 has about .36 mA Ioh.

You need a bank of inverters, transistors, or FETs to drive the LEDs.

Hope This Helps!
Rich


That might be true at extreme heat (257 degrees F), but
at normal temperatures the 4017 can source several mA and
drive LEDs directly. If you want a 4017 to drive a LED to its
max current rating, you have to use a high efficiency LED,
or use one of the driver circuits you mentioned to drive
a "regular" LED. The 4017 as wired in the schematic at
the posted url will work fine without drivers, providing
enough current to the LEDs for them to glow brightly.

Ed
.

Quantcast