what about a 555 running at 1 Hz. it's output connected to the clock of the 4029. then have the 4029 set to count down, when it reaches 0 the carry input will be brought high (looking at the logic waveforms, it's only brought high for 1 clock cycle, so you'll have to tell it to shut down somehow.)
4 dpst dipswitches could be used to set the timer, they would be connected to the jam inputs and another pushbutton would be connected to the presetset enable pin. So whenever you push the button, it takes whatever the dipswitches are set to (high or low) and loads that into the counter.
This will give you a total of 16 seconds.
here's the datasheet that I refered to: **broken link removed**
I cant wait until I'm assigned some real problems like this in my classes.
use a pic ffs, if ur doing gcse like me u should be fimiliar with pics and a program called pic logicator. use that with the time on the comparison block and then have it count however long then use the outputs to do or trigger whatever you need. this will shoud u can use outputs, inputs and pic logicator.