I don't know if this is the correct place to ask. Feel free to point me to an other NG if this is off-topic here.
On the 27th of November, there is "de dag van de wetenschap" (the day of science) here in Belgium, and I am helping out a local fablab on this event.
This event is aimed at kids between 14 and 18. I help out in the "electronics corner"
We are working on a setup where we want to show all kind of electronic sensors. To link electronics with science, The idea is to provide the visitor with a description of the internal working of a sensor, and let them find the correct sensor in the batch.
So I am looking for information on the internal working of different kind of sensors. For certain sensors, it is well known (hall-sensor, light-sensor, ... ) and in certain cases it is described in the datasheets (laser-based CO2-sensor or fine-particle dust-sensor).
But I am looking for information on the following sensors / devices:
On a sunny day (Thu, 27 Oct 2022 08:30:14 +0200) it happened kristoff snipped-for-privacy@skypro.be wrote in <tjd8hm$2mt7c$ snipped-for-privacy@dont-email.me:
I am old enough to know about "netiquette". Yes, I did do my homework before posting :-)
As said, for certain sensors, the datasheets do give me enough info to write a text for the 14-to-18 year audience.
But take -say- a BME280/BMP280, the only thing I can make out from the datasheet is that pressure is messured by a piezzo-electric element. For temperature and humidy, no info.
For the gyroscopes, I am wondering if they really messure the angular motion, or that they message lineair-motion in the x-y-z axis and then calculate angular motion based on that.
On a sunny day (Thu, 27 Oct 2022 09:33:35 +0200) it happened kristoff snipped-for-privacy@skypro.be wrote in <tjdc8f$2nc2l$ snipped-for-privacy@dont-email.me:
Google is one of the most valuable things we have for [self]education. Of course it only works if you are interested. Combined ith wikipedia it replaces that many "Winkler Prins" I think it was encecopedia books on your hobby sheleves ;-)
Well I do not know much about evolution of the recent humming beans species but when I was about ten years old I was reading 'Zo werkt de Televisie" and "Zo werkt de radio" from Van Aisberg (you are from Begium? should know that name). In those books he has somebody (Vraagal" asking the right questions for who he then gives the right aswers. Asking the right question is a very important thing. Somebody here constantly askes the wrong ones and I gave up on educating that person. At 14 I was designing tube amps for the school band, radio transmiters, what not So it all depends on the student's interest and the teacher.
Mesuring temperature is usualy easy, almost any conductor is temperature sensitive, if it is a chip then chances are it is a silly-con and perhaps uses a diode junction that has, what was it? -2 mV / degree C or so temp coefficient, diodes make perfect temperature sensors, used those in big projects.
So google solid state humidity sensors?
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pick your choice. maybe that datasheet mentions one of those methods in the first few lines? coud well be resistive or capacitive?
You did say 'hardware gyroscope' that leaves only this:
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But if you are talking about MEMS sensors, like your [possibly smart]phone has (at least my Xiaomi has)
Contact the manufacturers; NXP, TI, Analog Devices, ST Microdevices, etc. Their sales reps will be happy to show up with box loads of toys. I have one sitting on my desk; a 10 year old ST Micro Mems evaluation module. A giveaway from a seminar. If you're not sure who the manufactures are go to Digikey and Mouser search for sensors. Get the info direct from the horse's mouth.
Well, the idea is that these sensors would also have some kind of display with the measurement-data from the sensor.
So by -say- moving their hands over it, or blow in them, or move a magnet over them, or move them around, they would see a change in measurements (or not).
I agree, on sight, a lot of these sensors look alike. :-)
That is an interesting point.
E.g. a laser-based CO2 sensor has a light that flickers over couple of seconds.
It's indeed a good point to mention the physical aspects of the sensor (if there are) in the description.
OK but you might want to think about things that either look impressive or will engage well with the teenage participants. Sensors these days are very often boring black boxes with two or more leads coming out.
Obviously there are local and modern H&S considerations that some of my suggestions below may well fall foul of. I was in the last cohort to experience a real Maxwell's spur arcing and sparking as it spun up dipped in mercury scattering tiny globules over the bench as it did so.
Another nice optical one is sellotape on OHP slide and crossed polars. A crude variant of the basic physics of many interference filters.
Any diode will do for this if opamps are around. Or thermistors.
LCD thermometer plastic sheet is impressive if your budget will stretch to it (available from the likes of Edmund).
Hot wire wind velocity is another nice one (or traditional half ping pong balls on a stick and a magnetic read off).
Stepper motor to measure angular rotation speed isn't bad either.
There are some starting around the £20 mark eg.
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Best demo by far if you have the resources to make one is a bicycle wheel on a longish spindle with lead pipe wrapped around it and a high swivel chair. Put the victim on the chair and spin up the gyroscope then when they try to move the axis of the gyroscope...
It really drives home the effect of a gyroscope to handle one on that scale. Failing that the old toy lead ones that sit on an Eiffel tower.
Tesla coil and Jacob's ladder sparks make cool if RFI dense demos too.
Weren't fuel gauges in cars wire-wound potentiometers immersed in the fuel? They were 'safe' because the fuel to air ratio in the fuel tank was way too rich to be combustible.
I made this cork gun with a piece of steel pipe and a spark plug. Two drops of gas would pop the cork many meters into the air, but one or three drops would do nothing.
Yes. I think that airplanes now ensure a non-combustible fuel tank.
The capacitive level sensors also have wildly redundant intrinsic safety networks, lots of resistors and zeners. Suits me, since the protection networks add a lot of capacitance that makes simulation more interesting.
they don't make people pay for triggering it? they either avoided injury or did something dumb (it has a test mode to test if something will trigger it)
or have people pay a small fee to a cartridge fund if they want to use the tablesaw
There's a makerspace here it is ~$20/month half price for students Though they don't pay rent the location is provided by the municipality and I think they also get some subsidies by the government, like other non-profit organizations with an educational purpose
yeh, you have to plan ahead
you don't _need_ most tools, but they make it a lot easier and $50 is going to takes years to buy a decent metal lathe or table say
On a sunny day (Thu, 27 Oct 2022 19:02:51 +0200) it happened Jeroen Belleman snipped-for-privacy@nospam.please wrote in <tjedjs$9kg$ snipped-for-privacy@gioia.aioe.org>:
My highschool physics teacher did electrolysis by sending a current through water, then blew soap bubbles with the mixture H2 and O gas, and had us detonate the bubbles that floated in the auditorium with a lighted match. You quickly find out that the content and explosive force goes up exponentially with the bubble size. He also filled a steal pipe with spark plug with the gas and then once shot a hole in the glass cabinet at the back of the auditorium I would usually find a place a bit back from his experiments, The voltage for the sparkplug came from his Ruhmkorff coil demo on the same table.
The other physics teacher had part of a finger missing from one of his experiments.... He had us calculate nukes, critical mass etc :-)
It depends what you are trying to do and what kit the makerspace actually has. One of the ones about an hour from me has had laser cutters and a professional 3D printer long before they were common. They also had some CNC stuff and the blue wax for learning to use them and/or making lost wax casting moulds from.
Some of their kit was a bit wasted as most members were university students on a discount wanting to make their own electric guitars. Power band saws and sanders were in high demand as were spray paint booths.
Location was a bit dismal - think Bladerunner crossed with "Get Smart". That much kit in a rather run down cheap rent area takes some defending. Most of the other parts of the former cotton mill building were let out as band practice rooms. Electronics capabilities were a bit basic.
I have a 10" metal lathe at home and a table saw (with no safety features at all). The latter tends to trip the house RCD though - I think its motor is on it's last legs (or whatever motors stand on).
But for access to exotic would otherwise be unaffordable kit and spending a day using it then yes a trip to a makerspace can be worthwhile. It isn't unless you plan what you will do when there.
First, it looks like my small question on sensors seems to have turned into quit an interesting discussion.
I will try to answer some of the "sensor" remarks later on.
Some remarks concerning fablab / makerspace.
Op 28.10.22 om 11:05 schreef Martin Brown:
One of the things I do when I visit a city, is to visit the local makerspaces / fablab / hackerspaces and have a chat with the people overthere.
It's always a good way to learn about a city, because you get to meet people who really live there. :-)
First, one note:
there is quite a difference between the different types of organizations: hackerspace / fablab / makerspace. Some are mainly about "making equipment available", others are more a "social space" for like-minded people.
In some, everybody just does their own thing, in other, "sharing knowledge" is more important.
I'll use the term "space" here in a general sense.
In general, I see two reasons why people join a space:
1/ Using the equipment of the space.
And, for that, there can be two reasons:
- price, in combination with the amount of time you actually use it. Some of this equipment is simply way too expensive especially if you just use it not that much.
- Place. Especially in a big city, people live in a small apartment, and simply do not have the place to install all the equipment they need.
If you hobby requires you to have place and be able to make a lot of noise / dust / <whatever> , the 40 euro / month membership of space is still quite cheap compared to renting a garage to store your stuff.
2/ The social element.
Especially in spaces who have more a culture of sharing knowledge, having other people around you who can help you, is always a good thing.
In certain spaces, giving workshops is just seen as "a way to make money, so to keep the space running".
In other space, giving a workshop is more about "some people getting together to try out something together".
So it all differs from space to space.
A couple of years ago, I was talking to somebody why they had a 3D printer in their hackerspace. (that was when a 3D printer was still 800 euro or so).
He said "in a hackerspace, we have a 3D printer for two reasons: to allow people to learn about 3D printing and 3D design, and to print out a few small object if needed..
But if you do a project where you need -say- 40 pieces of the same thing, don't do it here. Go to a fablab".
I find this a good example of the different types of spaces, the different reasons why they exist and, hence, the different reasons why people join them.
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