This circuit uses two 4026B counter ICs in order to enable two 7-segment displays to count from 0-99. The first 4026B will output signals to the 1st display and 0nce it has counted to 9 it will return to 1 and activate the second counter which will count from 1-9, thus producing the numbers 11-19. This will continue through the thirties, fourties up to 99. There are many different 7-Segment displays around and this circuit may have to be adapted slightly depending on what display you are using. The seven segment display in this project assumes a 'common cathode' and the inputs are thus connected to the individual anode pins. For more help, please review the '4016B' in the ICs section of this site, I have written the information on the 4016B, in relation to the 7-Segment display.
2 4026B counter ICs
1 47K o hm resistor
1 NE555 timer
2 1K resistors (values will determin the speed at which the 4026Bs will count)