I have noticed that there are lots of temperature sensor projects out there in the internet, but the question is how many of them end up to be left on breadboard. I also found myself not hawing one that I could do simple temperature readings when ever and where ever I need. Lets see another simple temperature probe which is also a breadboard prototype. But with some work can be made in to portable probe.
rahulkar built this thermometer using Attiny85 microcontroller and LM35 temperature sensor. His probe is able to measure temperature from 0 to 150ºC or in Fahrenheit (selectable with button). Since Attiny is small IC he used MAX7219 7-segment LED display driver which accepts serial data. So he placed five digits to display full range of temperatures. He programmed Attiny85 with Arduino code which takes only few lines. To make probe more useful I would change circuit a bit to extend temperature range to negative as sensor can measure from -55 to +150ºC.
Using solar panel is a great way to harvest energy. But you cannot connect panel directly to battery or device. The angle of sun changes constantly, clouds appear what leads to solar panel output fluctuations. This is why a charge controller or inverter is used which takes care of smooth energy flow. Debasish Dutta have been successfully experimenting with solar energy harvesting and so he built solar charge controller.
He put Arduino to control the process. It takes voltage reading from solar panel and battery to be charged. Then according to voltage levels on either side he charges battery using PWM control signal. Energy flow is driven with MOSFET transistors that ensure low energy loss. He put significant effort in selecting right MOSFETs by going through transistor parameters and finding proper ones. Also his charging controller is equipped with basic filters on both – battery and solar panel sides. It seems really simple but efficient solution for hobby level use.
Electric guitars usually are connected through pedal where you can get various sound effects like distortion, delay, chorus and more. In any music store you can find that will fit your needs. Other way is to assemble your own using open source project details.
Electrosmash have shared his own pedalSHIELD which mounts on top of Arduino Due.
pedalSHIELD carries the analog schematic part of picking sound and output to cube. Guitar connects to input jack where signal goes through preamplifier to Arduino ADC. Then Arduino algorithm runs selected processing algorithm and then outputs waveform through DAC. Project files and program algorithms are shared if you would like to build one or even develop it further with your own effects.
Measuring temperature and humidity is really easy as there are many convenient sensors. Usually to measure humidity along with temperature there are combined sensors used like SHT21. Arduino even have libraries to get things working right away.
ff you want to display things there are more options and of course more work to do. Normally digital sensors are reflected in digital displays, but sometimes we like to look things old fashioned. So in this case analog display can be used. Kerry D. Wong built such device with couple analog displays where one indicates temperature and another humidity. Analog displays are custom made where arrows are controlled with couple servo motors. Driving servos with Arduino is also easy so overall code in project takes only few lines of code. It is set to take readings every 0.5 seconds. Temperature scale ranges from 50 to 95 degrees Fahrenheit and humidity from 5% to 95%.