We still don'tknow if the clock is a CMOS one, a TTL kit from the 1960's, or even one of those all-in-one clocks in one chip. A CMOS clock would be happy with 4 "D" cells and run a year on them, except for the display. A TTL clock will run down the 9 volt battery in a fairly short time. So while that in post#20 would work, there may be better options available depending on the clock's current draw and voltage regulation requirements.

 

We still don'tknow if the clock is a CMOS one, a TTL kit from the 1960's, or even one of those all-in-one clocks in one chip. A CMOS clock would be happy with 4 "D" cells and run a year on them, except for the display. A TTL clock will run down the 9 volt battery in a fairly short time. So while that in post#20 would work, there may be better options available depending on the clock's current draw and voltage regulation requirements.

It is a CMOS clock with 2 one transistor inverters and 6 diode OR gates, a diode AND gate, so it uses more current than a fully cmos clock. The 1 second clock source is from a wall clock module that has two transistors and an LED. There are two 7555 one shot multivibrators with LEDs. On battery power I'm guessing that 40 to 50 mA will be continuously consumed. So the 9v alkaline should last a few hours.