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dsPIC MiniTron Amplifier

dsPIC MiniTron Tube Amplifier

The MiniTron is a high end vacuum tube stereo amplifier with efficiency, distortion, and power output enhancements provided by some unique circuitry featuring a dsPIC30F2023 controller IC. The dsPIC is used in this project to create a tracking buck converter whose output voltage tracks the audio signal. The unique SMPS resources in these IC’s do most of the "hard stuff" usually required in an SMPS design, leaving ample processing power available for other activities.

These IC’s and the Avago galvanic isolators are truly the "enabling technology" for this project. The controller IC is also used to perform system health checks, and set the operating points of the individual vacuum tubes. This allows total system programmability, offering several possible preset operating modes.

© George Anderson

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Project Documentation

tag : Tube Stereo Amplifier, Audio, dsPIC projec


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dsPIC 33F128MC706 NUE-PSK Digital Modem

dsPIC NUE-PSK Digital Modem

PSK31 is one of the latest communications modes to capture the interest of hams worldwide. Its inherent ability to dig out low, near-inaudible signals is ideally suited for low power QRP enthusiasts. The PSK31 digital modem engine, however, requires intense DSP processing that is only commonly available in PC sound card. Thus the PSK operator desiring portability for field operation is locked into using a laptop computer as a controller, which results in a cumbersome station.

This project shows you design and construction of a standalone, battery-operated digital modem using a Microchip dsPIC microcontroller. The project includes a character display for transmit and receive text data, and a graphic display showing band spectrum and tuning indicator. Using GPL open source software, the modem can be homebrewed for less than $50 parts cost. When coupled with an SSB-capable transceiver or with a popular PSK-xx transceiver board from Small Wonder Labs, you too can have an effective portable PSK31 station.

© George Heron and Milton Cram

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Project documentation


tag : Digital Modem, PSK, DSP, MCU dsPIC33F128MC706, Communication


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H-1B or Outsourcing?

H-1B is non-immigrant visa in US under the immigration & nationality act that allows U.S. employers to temporarily employ foreign workers that has specialized knowledge needed by US employer. Usually many foreign IT worker that apply for this kind of visa. Discussing about H-1B visa for IT worker there are pros and cons about this policies.

The pro said that hiring H-1B professionals allow U.S companies to maintaining the highest standards of IT work regardless of location. Hiring trained and expertise can reduce cost thousands of dollar and extensive time to train worker to meet their standard. Bill Gates ever said that it's better to have the world's smartest workers developing new technologies here in the US than to work overseas where the benefits of new technologies may come first to overseas firms.

On the other side, H-1B gives ethical issues. First, these overseas professionals will taking jobs that U.S IT workers need. It means more jobless IT worker in US. Secondly, if H-1B professionals hired under unethical companies they can end up with less than they bargained for salary, working hours, duties, etc. H-1B visa holder must have the intent to remain in the U.S. only temporarily, They should ready to return to his/her home country at the end of the authorized employment period.

During economic global crisis, there is slow movement for H-1B visa application. If last years the entire quota for visas for the year, both 20,000 Advanced and the 65,000 quota has been reached on April 8, 2008 but this years until September 18, 2009, approximately only 46,000 H-1B cap-subject petitions and approximately 20,000 petitions had been filed.

There are two possibilities about this condition. First, US company start to hire US worker than overseas professional. It's good for US worker and government. This will reduce unemployed worker in US. For company, this could be more money and time to invest for training new worker to meet their standard. But, if the US worker already has specialized skill and meet company standard that would no problem, no more cost for training.

Second possibilities is US company choose to outsourcing their project overseas. Company think that outsourcing will cut the cost for salary since many third country has cheap worker. It also reduce facility cost for worker too. But If this happen, there will be more jobless people in US and it's bad for US economy.


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PIC Wireless Networks Wifi (Hotspot) Detector

PIC Hotspot detector
This wireless detector project allows you to sense the presence and relative signal strength of wireless hotspots. It is "always on" and communicates the presence and signal strength of an in-range hotspot by way of sequences of pulses - like a heartbeat you can feel. The stronger and faster the "heartbeat", the stronger the wireless signal detected.

This project consists of a microcontroller PIC 12F629, some custom interface electronics, a small vibe motor, and an off-the-shelf Wi-Fi detector from D-Link. The microcontroller periodically "presses" the button on the detector to initiate a reading. The microcontroller "reads" the output from the detector indicator LEDs and uses this as the basis for pulsing out a signal on the vibe motor, which the wearer can feel.

tag : wireless networks, hotspot detector, Wi-Fi strength signal indicator src

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AVR Digital Clock with Roman Numerals




This digital clock project will display a Roman number instead Hindu-Arabic numeral system (1,2,3... ). The project uses micro ATTINY2313 as main processor and LCD to display the clock. When you turn on the device, it will shows a screen flashes "Tempera tempus" as reminder to adjust the time.

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