Day 6: A long day

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The last day before the course’s end started.

Some teams had already comleted their protoypes’ main features and thus could concentrate on optimizing them and implementing additional features. Team “Bird hat” surprised with its needlework skills once again and created a wool bobble as input option for their inflatable hat. Teams “Blowfish” and “Ambileon” mainly dealed with their prototypes’ looks.


Meanwhile, other teams were busy to complete their prototypes on the whole and were forced to work through a twelve-hour day. Verena, assistant of the course, fortunately agreed to stay until 9:30 pm. During this time, three duplicates of the glow worm prototype were built, and team “Venus flytrap” was able to implement the program logic for their electronic plant.

We were pleased that a little guest visited us and stayed the whole day: Hendriks son came to test some prototypes and so sweetened our stressful day.

Day 5: Building frames and cases

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Today’s work was characterized by a lot of cutting, milling, shaping, etc.

All teams were in the progress of building different kinds of frames or cases to house the technical parts of their projects.

Consequently, the workbenches and drilling machines were in great demand.

Thanks to a Laser-Cutter available on the second floor, workable material wasn’t limited to wood.

The wonderfully pleasant smell pouring out  of the cutter told every visitor of the acrylic glass that was being cut.

First, the students sketched their drafts on paper, discussed different versions and later redesigned them in Adobe Illustrator.

Parts, the Laser-Cutter should cut out had to be set as hairlines (<0,001mm), while thicker lines could be used to imprint the parts with logos and other decorations.

The results looked so professional that more than one team decided to rebuild parts of their (eg. wooden) frames from glass.

Alongside this modelling, the projects’ technical aspects continued to mature and substantial progress was evident by the staggering amount of blinking LEDs, buzzing motors and humming compressors.

Day 4: Ready, steady, go …


9:00: We are finally getting started! Everyone is busily gathering boards, resistors, capacitors and cables, unpacking newly arrived components or hurries away to buy those parts that are still missing. Some groups even seem to plan to integrate unusual components such as umbrellas, inflatable mattresses or small plastic bubbles into their prototypes.

13:00: How to solve  problems, you did not know existed? The more our concepts are progressing, the more challenges have to be faced. Some basic solutions for often occuring problems:

How to connect RGB LED strips?

1. Connect the strip.  You find four wires attached to the copper tabs. In our example (left picture below) we have from left to right:

  • white coating: green LED color
  • yellow coating: red LED color
  • black coating: red LED color
  • red:  +12V

Some ready-bought LED-strips already use color coding for the wires: white for the power supply and then red, green and blue wires for the corresponding LED colors.

rgb stripe 2     rgb stripe 1

2. Set up the circuit. As our LEDs require more power than the arduino’s build-in power supply can provide, we have to connect an external power source and therefore need to add transistors to our circuit. In the setup used for the GLOW WORM LOVE project (right picture above), three N-channel MOSFETs for each single LED are used, which allows to actuate R, G, and B seperately.

circuit setup

[picture from: ]

3. Control your LEDs

In the Arduino sketch for every LED, the channels are defined:
void setup () {



and can now be assigned seperately to a specific value. For a nice purple we can use

analogWrite(REDPIN, 112);
analogWrite(GREENPIN, 0);
analogWrite(BLUEPIN, 112);

How to convert the sensor output of a LilyPad Temperature Sensor to  °C?

Usually it is sufficient to retrieve the raw values from the LilyPad Temperature Sensor, but sometimes, for example when you are designing user interactions, you would like to know the exact value in degree Celsius. So this is how you do it in your android-sketch:

1. Read the sensor output.
temperature= analogRead(yourInputPin);

2. Convert the achieved value to volt
voltIN = 3300;  //if you connected to 3.3V
voltIN = 5500; //if you connected to 5.5V
float voltOUT = temperature * (3300/1024);

3. Calculate the
factor =  19,8;  //19,8 mV per degree, if you are using a  MCP9701A
factor = 10,0; // 10 mV per degree, if you are using a MCP9700A
float tempC = voltOUT/faktor;

How to switch the direction of a DC motor?

For the blowfish group it is important to have a DC motor capable of switching its running direction. Therefore a circuit with relays is necessary. In fact, two relays are used. One to stop the motor and one to switch the current flow. The basic idea is to use a DPDT (double pole double throw) relay which separates two differently polarized circuits. Without activating the relay, the motor is +/- connected. When voltage is applied to the relay (the switch inside changes its position) the motor gets -/+ connected and runs in the opposite direction.

relay circuit

And some further creative workarounds for so far unknown challenges had to be found.


19:00: Time to go home. All five teams have already made substantial progress and the first premature prototypes are moving, blinking andmaking all kinds of nice sounds and less nice noises.

Some impressions:

led ball  team_work  umbrella1  umbrella 2

Day 3: Brainstorming

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The results of the brainstorming as .pdf:






Day 2

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The second day of the Sketching with Hardware course was dominated by the microcontroller “Arduino”. First, the advisor gave us an overview of the open-source project and the community around the Italian microcontroller. After a short introduction to the structure of the “Arduino” with its input and output pins we proceeded to install the required software on our computers. Once this was done we set out to test first simple examples. When all groups had a unit up and running, we could deal with more complex circuits.

Testing the particular examples was very practical. First, the advisors explained the circuits and their subtleties based on schematic drawings then each group could deal independently with the implementation. Input and output possibilities where covered. This included simple circuits with toggle switches which turned on and off an LED or more elaborate designs, which controlled the vibration velocity of a vibration motor with a variable resistor (potentiometer). The emphasis was on digital-read, analog-read and analog-write concepts.
Often, we were free to use any sensor to implement a particular principle which was fun to us and ensured that we understood the concepts and developed creative designs.

Towards the end of the day, the theme of the project week “Bionic” was presented. Some videos were used to further illustrate it. We were asked to gather ideas over the weekend which we would like to develop during next week.ImageImageImageImage

Day 1

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First day of the Sketching with Hardware practical course. When the advisors had introduced themselves and some formalities were settled, we started with the basics of electrical engineering. First, we approached the physical relationships between resistance, current and voltage. Then electrical circuits and their components were explained in more detail.
Once the most relevant components and their usage were illustrated, it came to hands-on testing. Armed with a multimeter, we proceeded to measure voltages and resistances and checked connections for continuity.
Based on this basic knowledge we constructed simple circuits on breadboards on our own. Equipped with battery, jumpers, resistors, diodes, switches, buttons and capacitors, we applied the previously learned contents practically.

Following the lunch break the course continued very practically. A keyboard controller extracted from a computer keyboard served as a starting point for small group work. The goal was to design a creative way of interaction for computer games. The concept was to short two contacts of the keyboard controller to send a specific signal to the computer. After we found out what contacts corresponded to which key on the keyboard (e.g. the arrow keys) we could replace these by self-designed switches.