As you may know best way to control DC motor speed is to power it with PWM (Pulse Width Modulated) signal. Microcontroller is good at generating PWM signals so Andrian build one using Attiny13 microcontroller. His need was to control 7A 20Volt motor. For this he used n-mosfet IRF540N.

To change PWM duty cycle he used Rotary encoder. As there were couple microcontroller pins left, he used them for LEDs to indicate MAX and MIN speed of motor. Important part of schematic is motor switching transistor. Using diode is necessary part as it takes care of inductive currents. Also there is a capacitor used in parallel of motor to reduce generated noise. So great small circuit to run small DC motors or use a general purpose dimmer for LED stripes.

Usually we use thermometers to determine ambient temperature. Anyway there can be more ways to do so. If we don’t want to follow the numbers we can see temperature visually. William made a PIC microcontroller based temperature candle which simply reflects measured temperature with RGB LED.

In order to know the actual temperature you need to reset circuit and then after power up it blinks blue LED showing tens of degree and then blinks RED for each single degree. After this is enters candle mode where it flickers color according to programmed color-temperature table. William even found nice use for it. He placed candle in a baby room to find out if temperature is suitable for sleep.

Scot’s friend turned 21 and he wanted to make an original gift reminding that she is now an adult. So he came up with breathalyzer idea. He didn’t expect it to give precise readings but relatively indicate the level of alcohol contributed.

Practically speaking all design is made of building blocks. The center of it is an Arduino Micro Pro. He used MQ3 alcohol sensor. Another thing he wanted was to make it portable with rechargeable batteries. 3.6V 1200mAh LiPo battery keeps it running for a long time. To make it simple Scot embedded an USB based LiPo charger, so not special adapters are required. All that joy he put in aluminum enclosure with a graphical LCD. Only single button is used which enables to put device in to sleep while pressing for a few seconds. Press again and it’s ready to operate.

Ocarina is a flute like musical instrument with several holes to change tones of pretty complex sounds. Cornell Students decided to synthesize ocarina instrument using FPGA direct synthesis algorithm. First of all they analyzed original ocarina sound spectrum to get amplitudes of each harmonic so they could create state machines to output them when played.

as it is air instrument they attached microphone to get air flow intensity which controls the volume of output. Simple six button board substitutes holes to change pitch. The results as you can see in the video are good enough to say that its ocarina like.