Electronics 2000

Hi all,

Need some serious help with this. I'm trying to make a Synchronous BCD Up & Down Counter with also a carry/borrow function. I need to a decimal counter that on a button push will count up by one, and on a different button will count down by one. Also I need to be able to string several counters together to have more digits.

The closest thing I have is this:But I cannot see a way to convert it to a synchronous decimal counter.

I have been searching the web for solutions to this but no luck. Any help would be greatly appreciated.

Thanks in advance.

I'm not sure the diagram will work as such, your count down is connected to the inverted outputs and you basically have drawn a series of divide by two counters that will only count up (some other problems with the diagram but as it won't do what you want I won't go into them). The other problem with using any push button to create a pulse is what you call bounce, the switch wont make and break cleanly so you need to devise a circuit that cleans it up using op amps and capacitors or some sort of RS flip flop setup.

How about a kit from Velleman such as this: http://cpc.farnell.com/velleman-kit/k80 ... dp/HK00785

Thanks paul,

That velleman kit may be exactly what I need.

Thanks

I need to look things up and think about it ... off the top of my head...

For up down use Q or NOT Q as they count in opposite directions.
To count up or down you pulse the clock.

You can get a single chip to do the counting, I am not sure what you want to borrow or carry adders and/or half adders.

I will look it up and get back to you.

Tar&stuff.

Sorry to count 1 you pulse the clock... for up or down change from Qto NOT Q.

Tar&stuff.