By using an RC oscillator and a
programmable divider, this counter can run for hours. An interval oscillator runs at a
frequency given by (see schematic):
f = 1 and R3~2R2
2.3 R4 C2
By using, for example, R4=390 K and C2 = 10mF and R2, the oscillator can run at 0.1 Hz.
Divided by 65536, this is a cycle of approximately 655 000 s (182 hours, slightly more
than a week). |