Simple rubber-band helicopter design can be enhanced with motorised power, flashing lights and other 'features'. Here is a howto for a prototype: http://www.instructables.com/id/Rubberband-Helicopters-step-by-step/
A simple robot… but how will you make it move and/or speak? http://makezine.com/projects/cereal-box-robot/
A disability switch is a very cheap and effective switch for people who have difficulty moving
A mat switch allows you to trigger an effect (or disable one) when someone steps in a certain spot. They're thin and generally about three feet wide so people won't step over them.
A home-made mat switch can be made very cheaply using cardboard and aluminium foil. Some trial and error will be required to get the sensitivity right.
Make a switch by covering two boards with aluminium foil over their entire surface. Attach electrical wires with tape, glue or alligator clips.
The middle layer separates the two foil sheets (say a sheet of paper sandwiched between the upper and lower foil surfaces). This middle layer has holes or strips cut into it. When the mat is stepped on, the upper layer pushes through the holes/strips in the middle layer and makes contact with the lower layer, and makes a 'closed' switch that can be used to control an electrical circuit.
The holes/strips in the separator need to be about a centimeter wide. The width will affect the sensitivity, i.e. the amount of weight needed to turn the mat on. The easiest way to do this is to cut inch-wide strips of thick paper or cardboard and tape them down across one of the foil sides like louvres. Tape them at their ends along the edge of the mat.
Tape over the last centimetre of foil along these edges to prevent contact at the edge of the mat where the layers aren't well separated by the strips. Also be sure the strips at either end extend out past the top and bottom layers at the extreme edge, otherwise the end of the top layer could fold over and make contact.
Mat Switch: Insulated strips between alfoil sheets | Door Switch: Burglar alarm | Momentary Switch - Normally Open |
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If the mat is to go under carpet, it needs to be MORE sensitive because the carpet spreads out the force of the foot. If the sensitivity is too low, it's possible for these mats to fail to trigger when a small child steps on them. Any ridges in the floor may make the mat unreliable (works best on a smooth floor)
Make a pressure sensor/mat alarm that you can hide under a rug? Then whenever your puppy steps on the alarm, it will trigger a sound. Place your pressure mat alarms strategically inside doorways/pet entry/exit points:
HINTS:
LINKS:
MATERIALS
METHOD:
Now, simply tape/glue the plates to the sponges so that the sponges hold the two plates securely apart and so that the FRONT/aluminium sides face each other but do not touch.
Testing: Attach the two wires/alligator clips from your your pressure switch to your test circuit. Push down on the plate to press the aluminium sheets together. This should 'close' your pressure sensor switch and activate your circuit!
If it doesn't work, check your connections. Do both wires actually touch the aluminium sheet? Do both wires ouch the contacts on your test circuit?
In case the foil does not make contact, scruch up some spare aluminum foil into a ball and tape the ball into the approximate cente of your two aluminium sheets. Make sure there is a space between the ball and the top sheet when there is no pressure, but that the ball touches both sheets when the two plates are gently pressed together?
If it works for a while and then stops working, make sure that the aluminium foil balls are NOT constantly touching each other. If the sheets are constantly touching, then stick a little foam only in the areas where the plates touch (so that they do not make contact)
To access the functions of an off-the-shelf radio controlled car, by taking apart the controller and adding minimal buffering electronic components
Adding wires and terminals/a proper connector on the radio controller unit and connect via a suitable cable to the GPIO pins on the Raspberry Pi (controls forward/back/left/right functions on the car by setting different pins on/off on the pi).
In Scratch, enable remote sensing and create variables with the exact names that the handler script was expecting. The script will receive these commands and then turn on and off the GPIO pins. Setting these different variables to 1 and then 0 could be put within all the other Scratch control and other commands available in the drag and drop interface.
Introduction to Scratch GPIO: http://pihw.wordpress.com/lessons/rgb-led-lesson-2-scratch-gpio-getting-started/
Normally, Scratch’s powers of control extend only to the screen and speakers attached to the Raspberry Pi, and usually actions are directed by the program flow or by external inputs such as the keyboard and mouse.
However, Raspberry Pi blogger “SimpleSi” (http://cymplecy.wordpress.com/) has produced a plug-in to allow Scratch to talk to the GPIO pins on the Raspberry Pi too. This allows Scratch to control “real things” and to respond to the “real environment”, which literally opens up a whole new world of possibilities: http://cymplecy.wordpress.com/2013/04/22/scratch-gpio-version-2-introduction-for-beginners/
Although a Raspberry Pi can be programmed to use Scratch to control the GPIO pins, because of the limited computing power of the Pi, once the Scratch scripts become longer and more complex, it starts to becomes quite slow to use.
However, there is another way of using the GPIO pins on your Pi – turn it into SID – a Scratch Interface Device - and simply use Scratch on a desktop/laptop PC and get it to remotely control the GPIO pins via a WiFi connection.
@gbaman is working on a full remote control suite https://github.com/gbaman/Pi_Connector but its not yet packaged up for classroom deployment so in the meantime, please try out the following code/instructions.
http://cymplecy.wordpress.com/2013/08/03/use-your-raspberry-pi-as-a-wi-fi-scratch-interface-device/
The Scratch GPIO handler program can be run with a parameter of an LAN IP address.
Run Scratch on the desktop of a PC/Mac/Linux machine (or even another Raspberry Pi) and write you code on that and get it to control the GPIO pins on your Raspberry PI remotely:
Your Pi will then listen for broadcasts from your main computer and you can simply run Scratch on yoru main computer, enable Remote Sensor Connections and then your Pi will pick up any broadcasts/variable changes that you make on your main computer
The current scratch_gpio_handler.py has the GPIO pins fixed to the following inputs and outputs. The pin numbers given, are the pins as counted on the P1 GPIO header itself.
Outputs (21,18,16,15,13,12,11) Inputs (26,24,22,19,10,7)
Broadcast Commands:
Command | Alt Command | Result |
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pinXon | pinXhigh | Turns pin X ON |
pinXoff | pinXlow | Turns pin X OFF |
allon | allhigh | Turns all pins ON |
alloff | allow | Turns all pins OFF |
pinpattern1010111 | Sets each pin ON or OFF depending on 1 or 0 [21,18,16,15,13,12,11] |
Other commands: You will need to see SimpleSi’s blog post for more information.
Command | Result |
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motorX | Runs motor X (A = pin11, B = pin12) |
sonarX | Trigger input on pin23, X = echo output on an input pin |
To use the input pins, see the blog pages for more information.
http://cymplecy.wordpress.com/2013/08/03/use-your-raspberry-pi-as-a-wi-fi-scratch-interface-device/
Control low level peripherals: http://elinux.org/RPi_Low-level_peripherals
http://pi-cars.com/2012/11/13/pi-cars-control-your-radio-controlled-cars-through-your-raspberry-pi/
Control using WebIOPi via web browser: http://rc-car.example.com:8000/app/gpio-header/
Programme Howto (driving test): http://pi-cars.com/2012/12/23/pi-cars-and-scratch-driving-lesson-1/