Jesper writes: This is another project which fullfills a need. I once built a frequency counter using plain TTL chips. That was long before the CMOS HC versions, even before LS was available. It could measure up to 50 MHz and worked quite okay, but the TTL chips was extremely power hungry. I think there was about 20-25 TTL chips on that monster. Well, but the old counter is now somewhere in the shed, and as I now again needed a counter, I did a bit more modern design.
It uses only 4 chips – 3 HC TTL’s and an Atmel At90S2313 microcontroller. It has a 5 digit LED display plus one used as a band indicator. Even with the LED display, the current consumption is less than 50 mA. It counts up to at least 52 MHz. I couldn’t find any signal source in the lab that could supply more than 52 MHz, so it may go a bit higher, but the fClock(typ) for the HC590 is about 35-40 MHz, so you shouldn’t really count (no pun intended) on more.
AT90S2313 Based Frequency Counter: [Link]