LED chaser circuit for 20 LEDs

[Damon Greives]

Hi
I'm pretty new to this, but I've built a simple sequential LED chaser
circuit in the past using a 4017 chip to sequentially make about 8 LEDs
flash. Now I need to do this again but with around 20 LEDs. Is it possible
to cascade two or more 4017s to do this? Is there an easier way?
Any help in pointing me to a reference or a circuit would be most
appreciated
Thanks
Damong

 

[David L. Jones]

"Damon Greives" <zz@elvis.com> wrote in message news:<40e80962@news.comindico.com.au>...

Hi
I'm pretty new to this, but I've built a simple sequential LED chaser
circuit in the past using a 4017 chip to sequentially make about 8 LEDs
flash. Now I need to do this again but with around 20 LEDs. Is it possible
to cascade two or more 4017s to do this? Is there an easier way?
Any help in pointing me to a reference or a circuit would be most
appreciated
Thanks
Damong

Some datasheets for the 4017 will show you how to expand them. Search
for something like 4017.pdf or 74hc4017 etc .
These days it's tempting to use a microcontroller for most things. In
your case a 28 pin PIC or AVR micro will do the job in a single chip.
Fairly easy to program in a high level language like BASIC or C.

Dave

 

[Mitchell]

I'ts is possible to do so using 4017 and it works quite well. I remember
using those decade counters
in the mid 70's when I was learning electronics.

I would dare so that there are more efficient ic's around now.

perhaps doing some BCD would cut the chip count.

I know that is not of much help. I hope that some of the
other guys that are much more knowledgable about this can help you?

Regards,
Mitch..


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.715 / Virus Database: 471 - Release Date: 4/07/04