Electronics > Beginners
Timer alarm
golden_labels:
darinsquared:
After building the primary version according to your initial idea, which you should do first before perfecting the device for various reasons (below), consider extending it by requiring some additional action after 15–20 minutes. Within a 5 minute period a PIR sensor can be triggered even without anyone around. In particular in kitchen environment, with both steam and radiation heating surfaces all over the place.
As for the reasons to first build the potentially worse solution: trying to make a perfect thing usually ends in not producing it at all. Fight the urge, uncontrolled perfectionism is really a horribly thing :). Second: it is unlikely that everything will work ideally upon the first run. It is easier to debug and tweak a simpler device, and it makes little sense to build extensions upon a platform that is not stable yet.
Wimberleytech:
As a software developer, I prefer to approach problems from the digital end of things too and sometimes I think that analog guys are way too much attached to their continuous domain solutions. But in this case I am forced to agree with them: it has a lower risk of failure, it is much much simpler, it is easier to debug/repair. On top of that the solution using specifically Arduino is pointlessly expensive: Arduino is good as an educational platform, but it is not a great choice for practical purposes if someone has knowledge of electronics and can handle a soldering iron.
Wimberleytech:
--- Quote from: golden_labels on December 01, 2019, 08:35:00 pm ---
Wimberleytech:
As a software developer, I prefer to approach problems from the digital end of things too and sometimes I think that analog guys are way too much attached to their continuous domain solutions. But in this case I am forced to agree with them: it has a lower risk of failure, it is much much simpler, it is easier to debug/repair. On top of that the solution using specifically Arduino is pointlessly expensive: Arduino is good as an educational platform, but it is not a great choice for practical purposes if someone has knowledge of electronics and can handle a soldering iron.
--- End quote ---
I respectfully disagree.
1) I am an analog guy.
2) As I posted, the arduino solution requires almost no effort. (I have not done the exercise myself to check for gotchas, but I will).
3) Arduinos are cheap. Depending on where you are...under $8. Yes, a 555 and a couple of caps and resistors are cheaper--I grant you that.
4) Arduinos are reliable. Can you site a reference that supports this reliability concern?
5) I have used Arduinos to make a reliable "bucket-level-detector" for my tractor. Works fine in a relatively harsh environment.
6) Yes, it is fun to solder up a 555 dip package on a perf board and hang some resistors and caps around it with wires here and there to connect to the PIR and buzzer. My lab is full of that stuff. Well...maybe put it on a pcb, no? OK, I do that too...fab my own pcbs when I want to stain my hands with ferric chloride, or slap one together and send it to expresspcb (that aint cheap).
I still stand by my position that an arduino solution would be nice.
Please rebut my points as I am happy to be proven wrong.
james_s:
I would probably use an 8 pin microcontroller, I've used the attiny series on a number of occasions. There's a tiny85 Arduino core but a project like this is trivial to do in any language, even raw assembly wouldn't be too hard.
Nothing wrong with the analog approach either though, or an oscillator driving a counter, this is one of those trivial projects where all kinds of different methods will get the job done.
Of course it also depends on the aging parents remembering to activate the device when they start cooking, so it might ultimately be more effective to have a functional smoke alarm in the kitchen.
Wimberleytech:
--- Quote ---
2) ... (I have not done the exercise myself to check for gotchas, but I will).
--- End quote ---
I built it. It works as expected. Simple, as expected.
Once you are in "code" land you can address issues (such as the one pointed out by james_s) with clever algorithms and perhaps other sensory inputs.
golden_labels:
--- Quote from: Wimberleytech on December 01, 2019, 08:59:56 pm ---Please rebut my points as I am happy to be proven wrong.
--- End quote ---
I would, if they would even refer to what I’ve said. :D
--- Quote from: Wimberleytech on December 01, 2019, 08:59:56 pm ---1) I am an analog guy.
--- End quote ---
I can’t disprove that.
--- Quote from: Wimberleytech on December 01, 2019, 08:59:56 pm ---2) As I posted, the arduino solution requires almost no effort. (I have not done the exercise myself to check for gotchas, but I will).
--- End quote ---
Except writing and testing software. I stress the second part.
--- Quote from: Wimberleytech on December 01, 2019, 08:59:56 pm ---3) Arduinos are cheap. Depending on where you are...under $8. Yes, a 555 and a couple of caps and resistors are cheaper--I grant you that.
--- End quote ---
By mentioning Arduino I meant it in comparison not only to the analog solution, but to digital alternatives. They’re much more expensive than even the corresponding microcontrollers themselves — not to mention anything needed for that task. Even with in the software domain this can be done at under 15% of Arduino’s cost.
--- Quote from: Wimberleytech on December 01, 2019, 08:59:56 pm ---4) Arduinos are reliable. Can you site a reference that supports this reliability concern?
--- End quote ---
I have never said Arduinos are not reliable. I claim that the software solution is less reliable. That arises from orders of magnitude higher complexity of both the underlying technology and the design, harder testing, less previous testing and higher chance of making a mistake in the first place.(1)
--- Quote from: Wimberleytech on December 01, 2019, 08:59:56 pm ---5) I have used Arduinos to make a reliable "bucket-level-detector" for my tractor. Works fine in a relatively harsh environment.
--- End quote ---
I was never talking about the environment. And if you did, I am happy you made something working. But your success doesn’t prove in any way that there are no better solutions or that someone else may repeat that with similar outcome.
--- Quote from: Wimberleytech on December 01, 2019, 08:59:56 pm ---6) Yes, it is fun to solder up a 555 dip package on a perf board and hang some resistors and caps around it with wires here and there to connect to the PIR and buzzer. My lab is full of that stuff. Well...maybe put it on a pcb, no? OK, I do that too...fab my own pcbs when I want to stain my hands with ferric chloride, or slap one together and send it to expresspcb (that aint cheap).
--- End quote ---
We do not know what the author has. We are on the electronics forum, so — unless clearly stated otherwise — it is a sane assumption that if someone wants to build an electronic solution, they will have to build a circuit on a PCB. Isn’t it? :)
Consider it a kind of a joke (I don’t suggest doing that), but with the 555 circuit presented above, you can go without a PCB: dead bug potted in epoxy or lowe temperature hot glue. ;)
____
(1) The easiness of turning an idea into software and its seemingly shallow learning curve misleads many people into false feel of comfort, despite their software is far from being reliable.
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