Counter circuit

[atollp]

Hi forum,

I'm having an issue with a counter circuit I'm attempting to build. I have followed the attached schematic in an attempt to build a 0-59 counter with NOT and AND gates.

I have constructed the schematic as shown however when I power on the circuit, the units will count up correctly, but when I try to get it to count down, the units will count down from 9 until 7, and at 7 the tens will count down one digit, and the units will continue to count down until it gets back to 7, at which point the tens will decrease again.

I would like, if possible, to have it count down until the units reaches 0, and then the tens will decrease a number. Is this possible?

What have I missed? Thanks for the help.

(to get to schematic scroll all the way to bottom of page and then scroll up until you get to the first two schematics, that is what I'm trying to build) http://www.doctronics.co.uk/4510.htm

 

[Harald Kapp]

This is an UP counter only.

See here: http://members.shaw.ca/roma/up-down.html
for a thorougz description of a 4510 based up/down counter.

Harald

 

[atollp]

Thanks Harald, I figured it out using a simple AND gate, but this website is really helpful