Erm, i've been looking around now and i have been tempted to get a few 7 segment displays to have a play with and do some projects - however the datasheets aren't particularly that helpful...

Can anybody explain to me how each number is made?

Ie, is one bar lit at a time and i have to say turn on specific pins to make a shape of a number? Or is it say pin 1 turns on number 1. (just an example)

Thanks

 

There are IC chips that take your input and convert it to light up the propper 'bars' on the segmented displays.

Look up the 7511. This is a 7segment display driver. There are different drivers for HEX input, DECIMAL, input or, BINARY input and can display the decimal equivalent on the LEDs

and read this:
http://www.allaboutcircuits.com/vol_6/chpt_7/9.html

 

The display has pins allowing current through the individual segments - http://en.wikipedia.org/wiki/Seven-segment_display

A decoder IC has a numeric input and translates that into the proper segments to light up to display that number.

 

There are common anode and common cathode LED displays.

There are pin(s) for the common and then a pin for each of the seven segments plus a decimal point if equiped.

A driver IC is usually used in conjuntion with the display which actually strobes or pulses the appropriate segments to create the appearance of the number or letter desired.

 

Your application will dictate the need for either common cathode (CC) or common anode (CA) displays.

You might be interested in looking at the 4543/4553 pair for a 3-digit counter.

For more fun, try duplicating that functionality using a microcontroller (this is a good learning exercise for multiplexing)

However, LED displays have been on the way out for a long time, in favor of LCD's. LCD's are much more efficient, if you do not count backlighting requirements. Each LED segment requires 10mA-20mA to drive, which is as much or more than an entire LCD display.

 

Well what i want to try and do is use a 4017 as a timer, as a small project for me to do - with minutes going up to say 99. I don't really want to go into the hours as it gets a little complicated for me

I understand the 7511 IC, and the fact i can count in binary it wont be a doddle to join each leg to a corresponding bit. However, the 4543/4553 as you suggested looks a little daunting for me. How does it work?

 

The 4017 is not the correct IC to use for your project. Neither is the 4543/4553 pair. It would be fine if all you wanted to do is count up from 0 to 999, and then start from 0 again.

Look for BCD counters.

Then look for BCD to 7-segment decoders.