10 Second timer

As a follow up to the previous post, I breadboarded up the timebase and added a counter. Due to lack of 4017 chips, it can currently only count 10 seconds and reset. This is quite strange as I could have sworn I had cubic buttloads of 4017 counters laying about in my parts bins. I had used them for a previous project and I usually never buy parts singly. There are probably more in a baggie somewhere, I’ll have to hunt or hit the shops to grab some more.

Timebase and 10 second counter

Timebase and 10 second counter

Murphy, in his infinite wisdom, decided to hand me a non-functional 4017 just to drive me crazy for half an hour wondering what I had mis-wired or thinking the clock signal was too weak to trigger the 4017 (which is foolish, of course it isn’t). After ripping another one out of the aforementioned old project (I’ll have to replace it later), it works a treat. Using the 1Hz output of the 4521 (see here) and dumping into the CLOCK input of the 4017, it increments once per second. Nice.

Next step is, of course, to obtain several more 4017s either from the nethers of my parts bins or from the shop and chain them together to count seconds, minutes and hours. The Easy part will be getting the 10s of seconds and minutes to reset when they hit 6 (60 minutes/seconds), the more difficult will be getting it to roll over at 23:59:59 to 00:00:00. I see a solution in the schematic to roll it over using a D-type flip flop so that will be educational as well.

See it in action:

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