for me works fine i just needed to add NOT gate at the end
see picture
ImageShack - Image Hosting :: 26740674jn6.jpg
The reason you had to use an inverter chip is because of a mis-match with your driver and display.
That is also the reason many people have trouble with a simple counter.
If your 7- segment display is a common cathode type, you must use a 7448 driver.
If your 7- segment display is a common anode type, you must use a 7447 driver.
Other points to watch:
Liberally use capacitors between the + and - rails to avoid spikes and glitches.
Use a regulated 5 volt power supply or fresh batteries totaling 4.5 to 5 volts with TTL chips (74xx series)
Make sure the input to pin 14 of the 7490 is clean. Debouncing is mandatory if using a switch for single pulse.
If you want multiple digits, you must use a 7447(8) for each display.
Place 220R resistors between driver and each segment.
I realize this thread dates back some 5 years, but there are always new people joining our group, hence the above information.