You can double the maximum current capacities of transistors, diodes, and some IC's by adding another one in parallel. Similar to how two LEDs in parallel use double the current, or two batteries in parallel can supply double the current. Driving high-current loads usually generates heat. In general, more current means more heat. Heat reduces... Continue Reading →

Old desktop computers are thrown into the trash by the thousands. You can salvage a power supply from one, or buy new at a computer store for under \$20. Then follow these instructions to convert to a very respectable high power benchtop supply. Follow all safety precautions! Detailed information and how-to: http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply Another tutorial: http://www.instructables.com/id/ATX--%3E-Lab-Bench-Power-Supply-Conversion/... Continue Reading →

The SparkFun 5V SPDT relay is typical of its kind. Although its coil needs only 5V to switch on, it needs more current than the Arduino can supply - although in practice it does work connected directly. Its coil resistance is 57 ohms, therefore it needs 88mA @ 5V to turn on consistently (i =... Continue Reading →

How to wire up the larger stepper motor from SparkFun using an H-Bridge (SN754410): (Images adapted from https://www.arduino.cc/en/Reference/StepperBipolarCircuit) Note where pin 1 of chip is (marked with dot or U cut-out). This motor requires 12V and up to 330mA of current. Red and Green wires are one coil, and Yellow and Blue the other coil. Motor... Continue Reading →

A voltage divider (also known as a potential divider) is a simple circuit that produces an output voltage (Vout) that is a fraction of its input/supply voltage (Vin or Vs).  In short, voltage is divided according to the ratio of the resistors. It has many uses but a common one is converting a variable resistor like a photocell or flex... Continue Reading →

Breadboard holes are sized for nice press-fit with 22ga solid wire (the kind we use for most stuff). The rows of holes are connected to each other inside, separated by a center channel. This allows for insertion of IC chips whose pins need to be isolated. The green highlighting represents holes connected to each other.... Continue Reading →

Most LEDs will burn out if connected to a 9V battery without a resistor. The resistor lowers the amount of current flowing through the LED. Read more here: http://www.robotroom.com/Pumpkin3.html (NOTE: in the breadboard photos there is power -red- on one side and ground -black- on the other, not next to each other like other, more... Continue Reading →

http://vimeo.com/38796545 With this noisy chemistry lab, the gamer will create his own jelly with water and a few grams of agar agar powder. After added different color, the mix is then pour in the molds. 10 min later, the jelly shape can then be placed on the game board, and by touching the shape, the... Continue Reading →

Scrollables is a series of multi-scroll devices, an exploration of possible applications for a paper-based tangible interface. As paper as a medium is more and more threatened by the introduction of portable multi-touch screens and e-readers, the project aims at bringing back the tactile relationship with this material as a way to interact with the... Continue Reading →