Posted on Saturday, April 2, 2011 • Category: Power Supplies
I'm replacing my old power-hog home server with a new one based on the Intel D945GSEJT mainboard. This board is essentially a netbook platform that's been "desktopified". Among it's weirder points are that it uses the Mobile 945GSE chipset, SODIMM ram, 44PIN IDE, and that it runs off a single 12V supply. The reason I chose this board is that it consumes 13W in idle and 18W under full CPU and GPU load which is pretty much the lowest power consumption one can get with an Atom system (excluding some server-specific boards that were beyond my budget). Not wanting to use an ATX PSU I've decided to build a completely new power supply for the board. Not having to bother with all the voltages needed for ATX makes this a lot easier. I've decided to make a high-amp 12V supply, and a 5V supply capable of driving two HDDs.
Posted on Wednesday, March 30, 2011 • Category: Amplifiers
This 200W MOSFET Power amplifier is suitable for many applications such as Guitar Ampplifier, Mic or Home theater.
As many people prefer because of its legendary robustness of MOSFET transistors. MOSFET amplifier is rated at 200W power with 4Ω speakers. It has good frequency range of 1 dB 20Hz up to 80kHz. THD is less than 0.1% at full power and signal to noise ratio when compared to 200W is better than -100 dB unweighted.
Posted on Sunday, March 27, 2011 • Category: Amplifiers
In this application, we are building a gaincard like amplifier. This application type is named gainclone in the audio world. To take a satisfactory audio response, we are adding equalizer to the feedback line and adding bass compensation also.
We are using LM3886 which is the revised version of its brother LM3875. These are the parameters that we are interested in. Honestly this values are much more better than many of HI-FI amplifiers sold in the market. Especially it is hard to find 110dB signal to noise ratio. And another property is, when there is no input, this amplifier is quite like a dead. It is nearly impossible to hear any noise when you stick your ear to the speakers.
Posted on Saturday, March 26, 2011 • Category: LED
This is great LED-controller board with lots of handy features. USB interface allows selecting operating modes directly on your PC screen without need additional input devices on boars. Project has preprogrammed several modes including slow and fast color change, temperature base color ,where color depends on temperature measured from temperature sensor (DS1821). Other modes include constant colors that can be configured with C# Win application. Actually there are more possibilities of usage especially when USB is used. Write your own or use PC application that would represent CPU load or other content with RGB colors. Project is built around PIC18F2550 microcontroller which comes along with USB interface. So USB requires couple elements what allows focusing on other parts of circuitry.
Posted on Saturday, March 26, 2011 • Category: Miscellaneous
MOSFET transistors are excellent choice for driving high current devices such as motors or high power RGB LEDs. They offer very low switching resistance and very small heat dissipation compared to bipolar transistors.
This guide is designed to explain how to drive P-Channel MOSFETs with a microcontroller such as PIC or ATMEGA. There are a couple of tricks to remember when using them. P-Channel MOSFETs are useful for switching positive supply of a target circuit on and off. Particular attention must be placed to the target circuit if the supply voltage is greater then the micro controller's logic voltages.
If for example, your target device is being powered by 12 volts, and your logic high state from the micro controller is 5 volts, then the MOSFET will never turn off, as voltage will either be -12V or -7V (remember that this guide is designed for logic level MOSFETs). Anything over -3 volts will generally drive the logic level MOSFET on (varies between types of LL MOSFETs).
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