Counting Circuit

[kevlar]

I am still somewhat new to electronics, and I was wondering if andyone could help out. I was wondering if anyone had a schematic for a digital counting circuit that can count from 0-99(decimal), be displayed on 7-segment LEDs, set to start at a designated number(hard-wired, e.g. 20), and count up or down in increments of 1 or 5. Oh, right - and hopefully using commonly found parts. Any input or help you could provide would be extremely helpful, and most appreciated.<p>
Please feel free to e-mail me at [email protected] at your convenience.
Thanks Much

[russlk]

The usual driver for a 7-segment display digit is the7447 or 7448 TTL IC. If you do a search for "BCD to 7 segment decoder/driver" you will find other ICs. The 7447 has a logic low output, the 7448 has a high level output.<p>The MC14553B is a BCD counter that can drive 3 digits by multiplex. There may be other ICs that do that, but I don't know them. I will try to send a schematic from the Motorola data book.