by Ken Shirriff:
Disassembling Apple’s diminutive inch-cube iPhone charger reveals a technologically advanced flyback switching power supply that goes beyond the typical charger. It simply takes AC input (anything between 100 and 240 volts) and produce 5 watts of smooth 5 volt power, but the circuit to do this is surprisingly complex and innovative.
Apple iPhone charger teardown - [Link]
This is a a regulated power power supply that is sized to plug right into the power bus strips of common solderless breadboards.
The board is assembled except for the headers which you must provide separately and solder in place.
Breadboard Power Supply Stick 5V/3.3V - [Link]
This project is able to power a USB device using two standard AA batteries and an electronics circuit. The circuit is based on LT1073 DC/DC converter to convert the 3V to 5V needed by USB. In that way it can power the USB device on the go.
USB Battery Pack - [Link]
Simple negative power supply (-5V / -12V / -15V) Sometimes you need a simple negative power supply. The best example is the contrast PSU for common small LCD device. Building -5V from a battery or a wallmart supply isn’t really easy.Here is a simple design small device that is able to provide -5V, -12V, -15V. He used the MAX 764/765/766 series. [via]
Simple negative power supply (-5V / -12V / -15V) – [Link]
Chris writes –
David Fowler at uCHobby has introduced his new-and-improved breadboard power supply, which is both an excellent introduction to soldering technique *and* a useful tool for further electronics work.
Indeed it is a nice little board – with additional header pins to bring power out to both sides of the board and add some extra stability. Jumper selectable 3.3/5V operation, plus one feature I don’t see often enough on supplies like this – a power switch. It seems one should consider adding a heatsink to that voltage regulator if you plan on using an input source higher than 25V. [via]
Breadboard power supply hits both rails - [Link]
Dave writes –
Sure power supply projects aren’t that sexy; but they are, generally speaking, the foundation for every electronics project. The voltage output for this project is 5VDC, and a practical output that can be applied to a wide variety of digital components. Even better, this power supply has a 2-pin plug that can be quickly and easily snapped into a common 2-pin header for a reliable and solid power connection. Add a pushbutton ON-OFF switch and a USB rechargeable interface and you have a versatile power supply that can be slipped inside your pocket. [via]
Make a Rechargeable, pocket-sized 5V power supply - [Link]
This is an instructable for beginners to teach you how to use an analog to digital converter. This will let you measure a ratio between a higher reference voltage and an input voltage. You will also need a 5v voltage regulator and a 3v voltage regulator (it’s not really needed) 5v for the higher reference voltage, and the 3v for the test reading voltage (it’s not really needed). A MCP3001 analog to digital converter from Microchip , another converter can be used if it uses the same method to transmit the measurement result, and you may need to modify the code.
The resolution of a A/D converter means the accuracy, and it ranges from 8 bit and higher, the more bits, the more accurate results you can get 8 bit resolution has a maximum decimal value of 255, which means you can measure 255 different voltages ranging from 0 to whatever reference voltage you are using 16 bits has a maximum decimal value of 65535, big difference in accuracy, but only twice the storage needed.
Digital Voltmeter – [Link]
Simple, low cost and easy to build power supply. Ideal for applications that doesn’t require too much power. It can provide power to circuit that uses less than 100mA without any problem. The disadvantage of this circuit is the danger of an electrical shock, so it cannot be used if the circuit is in contact with the user. The voltage supplied by this is determined by the zener diode.
Transformerless Power Supply - [Link]