Need a powerful multiplexer...

Hi everyone. I was thinking about a nice project that would be interesting to develop: a LED clock. Here's how I imagine it (roughly):

I was wondering if there's a multiplexer huge enough to handle, let's say: - 1 LED / second = 60 LEDs - 2 extra LEDs / 5 minutes mark = 24 LEDs - 4 digits, 9 LEDs high * 5 LEDs width = 27 LEDs - 1 comma = 2 LEDs Total: roughly 110 LEDs... So I need a 7bits multiplexer? a 128++ pins monster? Does it exist?

I would highly recommend using shift registers. The data rate is going to be very slow, one change per second, and the logic of a shift register is VERY easy with something that is set sequentially like this.

Could you develop a bit ?

Look into the TLC5940. It is essentially a shift-register with built-in LED drivers.

you could also use normal registers, 74*374, etc. They need more pins (although this can be reduced using a decoder for the address lines) but are far faster than serial shift registers.

Wow, I just took a look a the TLC's datasheet, I think this baby's just took complicated for me! But I haven't mentioned that I just have figured out how to handle a SN754410 and didn't succeeded with 74HC4051 ;)

Wow, I just took a look a the TLC's datasheet, I think this baby's just took complicated for me!

With the Arduino library, it is much easier to use than rolling your own solution.

You can use several 32 bit ADG731 mux, very easy to interface and you can cascade however many you want.