Picoboard and Wedo with Scratch

Replies to Claudia and Anders:

I'm glad to have found this forum. Although Scratch isn't new here I don't know  anyone who has worked with the Picoboard or external Sensors.I love Math and know a bit about programming .

Claudia , thanks for your answer! From below you can see I had already seen your name somewhere!I am very sad to say my laptop was stolen last year but its still all in my head and will be happy, if you're interested and given time to share code examples. Anyway I hope to redo some projects this year as well as try new ones. Wow,the idea you shared has everything to do with my views on the use of Scratch and I actually did that last year except for the humidity sensor! We saved data ( for example pairs of numbers  , time and temperature )in lists , exported as text,  then opened with Excel and did all kinds of graphs.

Found out about Scratch before it was actually introduced in my country, loved it, tried  to learn as much as I could when I could ( time's always scarce...) and am still doing so. Portugal actually has its own Scratch site  only very  recently updated with Scratch 1.4. There is a very comendable organization of teachers here around Scratch.However, although Scratch is great for story telling and getting little kids to learn basic programming skills , here I haven't really seen its use advised for older kids. It has been mostly "promoted" for use in Math with 5th and 6th graders and before I prove them wrong some of my pupils say its " kiddy stuff",which is a pity when you can also create  interesting programs using more advanced concepts  with grades 7 all the  way up to 12 ( get kids to create "missing operators" with exponential and logarithmic functions...)

Hope to hear from you Claudia!

Here are  some ideas I used :

Turned a bycycle upside down, taped a magnetic sensor to one part of the bike and  a little magnet to the wheel.The idea was to get the wheel to spin for a bit and calculate things  like:distance "travelled", speed and rotations per minute. Got the idea from the gadget on my husband's mountain bike.

With the Temperature sensor got it close to really hot  or cold things and with pre-recorded kids' voices you could hear " It's soooo hot" or "It's sooo cold."

I had thought of a " talking" plant who would complain if its soil was too dry but didn't find a humidity sensor in Portugal ( resistive humidity sensor) . I'm going to order from Rhopoint but it's going to really cost me because of shipping. Do you know if can use this sensor to measure soil humidity as well as  air humidity? Another hare brained idea I didn't get to try was a doll with a humidity sensor on an adapted diaper. She would cry out "Change me" when water you put in her mouth trickled down to the diaper...

With four mercury switches taped to a plate which was then covered with transparent hard case with holes as a precaution and we simulated a steering wheel which controlled a car on the screen. We were very, very careful but the Wedo tilt sensor is of course the way to go.

We also filled the screen with flowers of various colours and with the light sensor placed on the screen there was this little bumble bee which flew to where the sensor was.There was only one flower of each colour and at any given time the Scratch program knew exactly what flower the light sensor was on.

Anders, thanks for the info. I haven't tried Mesh but it seems to be the only way to control more than one Wedo kit. Of course you'd need more than one computer but with shared variables and broadcasts there are a lot of possibilities...Regarding  resistance, for example I used Temperature Sensor 10 K OHM, Light Sensor 5K to 20 H OHM. Electronics isn't my specialty but after finding the following info I ordered a Picoboard and later on managed to get the external sensors in Portugal except the humidity sensor.

Hope  the following info answers some of your questions.

Sorry for enormous post.Please excuse any errors!

Very best regards,

Ana Santos

From Sensor Types and Sources: I knew your name was familiar Claudia!

The following list shows different types of sensors that have been used in Scratch Sensor Board projects. (They are typically attached to alligator clip-heads plugged into sensor board jacks A, B, C or D.) Visit the vendor site for pricing and ordering information.

 Name; Description ; Vendor  Part Number

18. Um. OK. But in reality, how do the resistance values relate to the sensor value? Is it linear?

Nope. It's not linear. It's logarithmic. From experiments on our board, the resistance sensor value (0-100) that the PicoBoard produces is related to the actual resistance, R, (in KOhms) across the alligator clips by the something like the following equation:

sensor value = a*ln(b*R+1) where, approximately:

a=19.5
b=0.9

BUT, if you are only interested in low resistance values between 0-10 KOhm, the following simple relation works real well (and yep, it's linear):

sensor value = a*x, where a is approximately 5.57

Thanks Anders and Karen, that´s really good to know. All computers in schools all over the country have W. Vista.LOL Lots of chuckles from  that salesman :)))

Since the Picoboard works on them and on my Win 7 laptop, I'll cross my fingers.  I was even considering  Mesh which allows computers on a local network to view each other's variables and see broadcasts.Theoretically, if you place sensor inputs in variables all computers could see them and one "Master" computer could control motors on other computers based on inputs from a Picoboard or whatever.

I'm green with envy Anders, lived in Canada for many years and I miss the snow. But I do love beautiful sunny Portugal, so there :).

IrisSophia