Tag Archives: Power

Triacs – How to calculate power and predict Tjmax

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An application note from NXP on how to calculate the power dissipated by the triac:

This Application Note describes how to calculate the power dissipation for triacs and Silicon Controlled Rectifiers. Thermal calculations are also included to help the circuit designer to predict the maximum junction temperature or calculate the required heatsink thermal resistance. Four worked examples ensure that all the power and thermal questions that arise during the design process are covered.

Triacs – How to calculate power and predict Tjmax – [Link]

Get a constant +5V output by switching between a +5V input and a single-cell LI+ rechargeable cell

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App note from Maxim Integrated on providing smooth power from two sources. Link here (PDF)

Design provides a simple method for maintaining an uninterrupted +5V even while switching between the external +5V supply and a rechargeable single-cell Li+ battery.

Get a constant +5V output by switching between a +5V input and a single-cell LI+ rechargeable cell – [Link]

Non-Invasive Smart Electricity Meter

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A simple Non-Invasive Smart Electricity Meter using Spark Core. By Yonas Leguesse @ hackster.io:

A non invasive current sensor is connected to the spark core (with a few components), and clamped around a cable in the Mains distribution unit. No wiring is required, however Do not try this at home, as the Mains Distribution Unit should not be tampered with unless one is Licensed to do so.

The back end is Web Application hosted on a LAMP (Linux Apache MySql PHP) setup. Initially it was hosted on a raspberry pi on a LAN, but then I decided to host it on a hosted server. Both instances worked well, its just a matter of preference.

The spark core simply takes periodic readings and sends them to the server, where all of the calculations and filtering is done.

Non-Invasive Smart Electricity Meter – [Link]

Emon-server – 555 Timer as power usage sensor

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by dkroeske @ github.com:

A cheap 555 timer chip acting as Schmitt trigger combined with a phototransistor or LDR is taped to the ‘flashing light’ or ‘pulsing magnet’ on the electricity meter. The output of the 555 timer chip is connected to one of the GPIO pins on the Raspberry Pi. A Python script (executing in the background) recording 555 events is calculating actual energy usage [e.g. Watt] every time the 555 is signaling and stores epochs in an SQLite3 database. From this, another Python script (executed from e.g. cron) generates all kinds of energy usage information (e.g. kWh or kWday or whatever). Using Node.js (running on the same Pi) all data is ‘RESTified’ enabling spreading out to the W3. To maintain privacy JSON web tokens are required every time the service is queried. Oh, and there is also a Pimatic plugin available (here)

Emon-server – 555 Timer as power usage sensor – [Link]

AC Power Theory – Arduino maths

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by openenergymonitor.org:

AC Voltage and current continually alternate, as the name suggests, if we draw a picture of the voltage and current waveform over time, it will look something like the image below (depending on what’s using power – the current waveform – blue in the diagram below – is what you get if you look at a typical laptop power supply. There’s an incandescent light bulb in there as well).

The image was made by sampling the mains voltage and current at high frequency, which is exactly what we do on the emontx or Arduino. We make between 50 and a 100 measurements every 20 milliseconds. (100 if sampling only current, and 50, if sampling voltage and current – we’re limited by the Arduino analog read command and calculation speed).

AC Power Theory – Arduino maths – [Link]

Researchers Claim 44x Power Cuts

rcj_Transceiver_SRC_University_of_Illinois

by R. Colin Johnson @ eetimes.com:

PORTLAND, Ore.– Researchers sponsored by the Semiconductor Research Corp. (SRC, Research Triangle Park, N.C.) claim they have extended Moore’s Law by finding a way to cut serial link power by as much as 80 percent. The innovation at the University of Illinois (Urbana) is a new on/off transceiver to be used on chips, between chips, between boards and between servers at data centers.

The team estimates the technique can reduce power up to whopping 44 times for communications, extending Moore’s Law by increasing computational capacity without increasing power. “While this technique isn’t designed to push processors to go faster, it does, in the context of a datacenter, allow for power saved in the link budget to be used elsewhere,” David Yeh, SRC director of Integrated Circuits and Systems Sciences told EETimes.

Researchers Claim 44x Power Cuts – [Link]

Power and Dependent Sources

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Determine the power absorbed by the VCVS in the figure. Solution: The VCVS consists of an open circuit and a controlled-voltage source. There is no current in the open circuit, so no power is absorbed by the open circuit. The voltage vc across the open circuit is the controlling signal of the VCVS. The voltage Vc (across 2 ohm resisitor) measures vc to be vc = 2V. The voltage of the controlled voltage source is vd = 2 vc = 4V. The current in the controlled voltage source is 6V/4 ohm= 1.5A. The element current id and voltage vd adhere to the passive convention. Therefore, p = id*vd = (1.5)(4) = 6W is the power absorbed by the VCVS.

Power and Dependent Sources – [Link]

Power playground project

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Spacewrench over at Dorkbotpdx published a new build, a Power Playground project:

It’s a PMOS/NMOS H-Bridge with FETs that can handle 3 amps or so, plus a SPI current sensor, some switches & a rotary encoder (not stuffed yet), and a 7-segment display, all controlled by a Teensy-3.1 running FreeRTOS.

I made this because I’m always running into battery, power, inductor and transformer issues I don’t have any experience with. The idea is to use the H-bridge configuration and current sensors to experiment with moderate-current PWM, motor control, power-line synchronization, battery charging and discharging, etc.

[via]

Power playground project – [Link]

Delivering efficient, reliable power through GaN

 

GaNFET

In a world with a growing population and ever-expanding need for energy, achieving more efficient electrical power conversion is crucial, but presents a number of challenges. GaN technology offers a solution, delivering a number of advantages to ensure availability of reliable electric power.

TI’s latest whitepaper explores the role of GaN in the power supply chain. Read up on its advantages over silicon for power supply switching, and technology advancements required to create complete system-level solutions for GaN-based designs.

Delivering efficient, reliable power through GaN – [Link]

DIY Digital AC Watt Meter

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by electro-labs.com:

Have you ever been curious about the power consumption of an appliance? For example did you wonder how much it will cost you to leave your television in standby mode whole night? Or did you want to learn how much change your refrigerator settings will make on your electric bill? If your answer is yes, you can use a wattmeter to measure the power consumption of a device. In this project we are building one.

This is an AC Watt Meter which can measure the real power consumption of a device connected to the 230Vrms/50Hz mains line. The PIC microcontroller collects the voltage and the current information with the help of ADCs and then calculates the RMS voltage of the mains line, RMS current drawn by the device and the resulting average power consumption. All these information is then displayed on the dot matrix LCD.

DIY Digital AC Watt Meter – [Link]