Increasing current capacity by doubling components

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 →

Making Your Own Cheap Power Supply

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: Another tutorial: Continue Reading →

5V SPDT Relay

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 →

Voltage Divider circuit

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 internal connections

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 →


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 →

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