It took a while (several hours actually), but I finally got the 1Hz signal generator working on the breadboard. There was only one minor error in the schematic (see links) which I have corrected. I still don't have a oscilloscope to test the signal frequency, but the LED appears to blink in time with a digital clock that I have so I am fairly confident. I guess I will have to wait for the clock to be fully assembled and then see how well it keeps time.