Electronics > Beginners

Timer alarm

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james_s:
I'm not sure I'd worry too much about it being a safety application, currently there is nothing, having anything that reminds them sometimes even if it is not 100% effective is better than nothing.

jhpadjustable:
Oh, right, my mistake. I had taken the ideal, "a relay on the power supply to the stove that would cut out when there is no motion for extended period," for the minimum. So much for not stretching! :)

Zero999:
I'm also an analogue, more than software person. I'm not scared of code. It just doesn't interest me so much.

Yes, all of the options discussed above will work. If I had to pick one, it would be a simple 6 or 8 pin microcontroller, probably programmed in good old assembler.

I don't see how a 555 timer is any more reliable than a simple microcontroller. The 555 timer has its quirks. It's prone to false triggering and resetting, due to glitches in the supply voltage which can be caused when the output pin changes state, which results in huge current spikes. I know software can be prone to bugs, but that tends to be the case for complex systems, running on a deep software stack, containing many potentially buggy libraries and drivers. Such a simple program, running on a basic microcontroller, should be fairly reliable, given sufficient debugging. It will have less components, than an analogue design, therefore fewer parts to go wrong. We also mustn't forget that the timer is only a small part of the system. There are other parts such as the: power supply, PIR sensor, relay and alarm which have the potential to fail.

Wimberleytech:
OK golden_labels, you have bested me.  I declare you the winner.

golden_labels:
It is sad that people get so deeply emotionally involved and hurt as a reaction to a simple event of someone else noticing possible problems with their solution — not even claiming that they’re outright wrong or their it is crap, but just that it may be lying at a position worse in some scale than some other option. :(

No one has won, because there never was any fight. Though you may perceive it in a different way. After all I’m not totally immune to XKCD 386 myself.

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