Here is a numitron clock I prototyped
using 4 DR-2000 RCA Numitron tubes. The clock
chip I used is 7317B which is the same as the MM5387AN. This clock chip is 4 digit
direct drive only and also has an alarm. My next step is to wire a buzzer for the alarm to
wake my son up!
The clock chip was purchased on
ebay 25 for $24.95, not to shabby! I used 4 ULN2002
darlington driver ic's for which I have over 1000 in my stock. I know, the wiring is sloppy!
(you should see the rest of my bench)
On my breadboard, you will see 2
bulbs which flash every second for the
colon. This clock chip will also drive led's directly.