Where to buy 3-4 digit 7-segment display?

Forum 2005-2010 (read only) Hardware Interfacing
1

Hey,
I'm working on a project that I would like to have 3 or 4 digits of 7 segment displays. I currently have one digit set up using 8 pins, but that obviously won't work for 3 or 4 digits. I read about the libraries to control MAX72xx drivers, but where do I get this? Ideally it would be all assembled and I would just have to connect the four (right?) pins and use one of the libraries from this website.
Thanks

2

I probably wont be any help, cause I like quite the opposite, that is not assembled and using what i have making it work.

that being said, if you dont mind probing things out, the cheapest place I have ever found for all sizes of 4 digit displays is the thrift stores, in the form of old alarm clocks

3

I thought about it, and it's stupid to buy things pre-assembled when I can assemble them...
So I think I need a cheap source for the driver (MAX72XX right?) and help setting up the circuit to make it work. I can do surface-mount or through-hole soldering and I have perf circuit board. How is one of these chips set up?

4

Bump, any help?

5

I think I understand everything except the capacitors in the MAX7219 schematic. Are they 10uF and 100nF?

6

only caps i see are 0.1uf, which are usually ceramic and marked 104

7

I'm confused by what looks like two capacitors in this schematic:
http://www.arduino.cc/playground/Main/MAX72XXHardware#Wiring
I just realized that 100nF is .1uF, so that makes sense. What about the 10uF one? Wouldn't these two in parallel essentially be a 10.1uF cap?

8

yea, and i am not experienced enough to tell you WHY someone would do that ... you could probably omit the .1 as the tolerances on a 10uf electrolytic would probably make up for it

personally if your design is so dependent on an extra .1uf as the author makes it sound, you should back it up with data

The original sheet just uses a .1uf to smooth out any power issues, in the perfect situation, 10 would provide even more, 10.1 sounds like more crap to fiddle with

9

There is a page, where Grumpy_Mike wrote about the capacitors:
http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

10

I think I'll just go with a 10uF and change it if I have problems. Thanks