In this youtube video watch how to solder solar cells together.
DIY: How to solder solar cells - [Link]
This project is an automatic garden light using a LDR and 6V/5W solar panel. During daylight the internal rechargeable 6 Volt SLA battery is charging from the solar panel. When there is dark the battery is powering the white LED string.
Outdoor Garden Solar Lights - [Link]
Ruby is a battery-powered amplifier and it is an “enhanced” version of the Little Gem. This amplifier is based on LM386 chip and has an input buffer that is feeding the inverting input. The input buffer helps to retain treble detail going into the 386 chip. It is powered from a single 9V battery. Check schematic and construction details on the link below.
Ruby : A battery-powered amplifier – [Link]
This video shows how to build a handheld 1W 445nm blue laser torch. This laser is focusable that means it can burn and light matches. You will need some parts found online to build it and this is not recommended for beginners. There is also some build kits available.[via]
DIY: How To Build A 1W Burning Blue Laser Torch - [Link]
TeenyChron project is a clock that pulls time from a NTP server and uses a Garmin GPS module, a TS-7400 single board and two displays to display both UTC and local time. The heart of the system is a single board computer based upon an ARM processor running Linux. This project is well documented and you can find more information on the link below. [via]
TeenyChron: A Linux-based GPS-synched NTP server – [Link]
This project shows how to build an Arduino thermostat using a thermal resistor as temperature sensor and a potentiometer to set the triggering voltage. 8 LEDS (4 Green, 4 Red) shows the triggering temperature in hex value and a servo motor is controlling the air conditioning knob. The Arduino code is simple enough. [via]
Air conditioning thermostat using Arduino - [Link]
These days digital to analog converters that are used in audio systems, come in integrated circuits (ICs). This project shows how to build a digital-analog-converter using discrete components. The fundamental building block for the Discrete DAC is an R-2R ladder network. To learn more about how a discrete DAC works follow the link below. [via]
DIY discrete digital-analog-converter – [Link]