[HD2 General] motoi_bogdan:
@T-Macgnolia

the battery was linked to the phone in the same way it's normally linked, but the connectors were extended with some wires. The mutimeter was placed across the positive terminal. However i found out that if you disconnect the positive terminal of the battery while the phone is still connected to a power source via usb and turned on, the phone will still work. It was usefull as i could estimate the total power consumption of the device while draining energy from a single source. As other HTC phones, it is possible to start HD2 and use it without a battery, as long as the phone detect a voltage (1.2 -3v) across the center pin and the negative one. However i don't see a practical use for this, other then troubleshooting a dead phone to check if it's problem is battery related or not.

About Velleman's device, i find as a good enough multi purpose device. However is nowhere near as precise as the Fluke 127 at resistance/capacitor measurements. Voltage and current are ok. It's a good device for hobby use, however the test leads connectors on the device are... crappy to say the least. Autoranging works slower then the fluke but hey.. you're talking about a $80 device. On that price range, it's a good device, if you have the time to tweak it a little, add a secondary circuit braker on the 10amp mode (damn thing doesn't have any protection, I blew a circuit track while measuring 6A!!) and replace the test lead connectors.

@clarknick27

will do.. chose one and post the link and by the end of next weekend i will have some results. I will wait to have some 2-3 roms to test before hacking up the phone again :D

@reijkelhof

it is true that black screen are good, but for amoled displays (or plasma screens for tv's). In that case, the individual subpixel element creates light by it's own. An amoled screen can achieve greater contrast because when displaying black, the organic led's composing the display's matrix are simply switched off. Thus.. no power consumption. When displaying white, all those elements are switched on and lighting at full brightness - max power consumption.

HD2 has a simple LCD display - twisted nematic matrix. The Iphone has also a LCD display - in plane switching matrix. Although different they use basically the same principle. The matrix itself cannot create light, but uses small liquid crystals that can change their transparency level if a small electric current is applied. A small crystal is placed for each subpixel - 3 for every pixel on the screen. Each crystal is controlled by a vertical mosfet transistor - that will switch the crystal to different states of transparency in order to block or allow light to pass. When no electric signal is passed, the crystal is almost 100% transparent and when full power is applied, the crystal is almost 100% opaque - note the use of "almost opaque" due to technology limitations a LCD display cannot obtain true black because it cannot switch the crystals to 100% opaque. Thus we get some sort of dark grey. Well, if the matrix doesn't produce light and only can transmit/reflect it... where does the light comes from? Simple.. the back layer of an LCD display has a backlight composed of small led's - that's the light source for every lcd phone screen. It's always ligthing, even if you display a black screen (in that case the LCD matrix is opaque to the light and it cannot pass). So.. if you have a black screen - all the crystals are switched "on", full power is applied to each mosfet transistor. Thus more power being used by the display. If you use a white screen - the matrix is powered down so .. lower power consumption.

So a combination of light colors and lower backlight uses less then about 50-60% of the energy needed for a full backlight screen displaying black color. That's for the HD2 screen. Amoled's are just the opposite.