delabs Circuits

Monday, December 18, 2017

Calculate THD - Total Harmonic Distortion

I want to know about IEEE 519 Harmonics standards. And Formulas to calculate Total Harmonic Distortion (THD) for Voltage and Current according IEEE standards. Till now i am calculating by taking Square root of the ratio of the sum of the squares of the total harmonics to the fundamental harmonics.

And i am measuring the I THD and V THD by using fluke meter. I want to know how to calculate the THD as per IEEE standards.

Mail from RB

Have a look at these pages .. Total harmonic distortion In power systems, lower THD means reduction in peak currents, heating, emissions, and core loss in motors.

IEEE Std 519-2014 (Revision of IEEE Std 519-1992) - IEEE Recommended Practice and Requirements for Harmonic Control in Electric Power Systems

This document sets the quality of power that is to be provided at the point of common coupling.

Harmonic Currents - Power quality

Power quality used to be to the ability of the electric utilities to provide electric power without interruption. Today, power quality encompasses any deviation from a perfect sinusoidal waveform. This includes EMI and RFI noise, transients, surges, sags, brown outs, black outs, and any other distortions to the sinusoidal waveform.

Calculate THD - Total Harmonic Distortion

Spectrum Harmonic Analysis Software

Spectrum harmonic analysis software makes it possible to identify and mitigate harmonic and power-quality problems with a few simple mouse clicks—straight from a dynamic one-line.

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Thank you sir,
i ll try to go through the web sites.

Mail from RB

Friday, December 15, 2017

Door access controller with Biometrics

I am trying to design a 4 door access controller. I have a complete working board of fingerprint scanner with DSP for fingerprint verification and authentication.

I wish to design a microcontroller board which will communicate with this board to trigger the scanning process, store the data in PC and operate 4 relay circuits using the external wiegand relay output of the DSP. thanks in advance

Mail from RU

Have a look at these links. Use one that is available and build your software on that.

Door access controller

Access control system

A numeric code access would be simple and cheap, but it means sharing the code, which could easily be given to unauthorized users. Changing the code and making known of the change

Embedded Access Control and Biometrics

An embedded access control application on the controller eliminates the need for software or servers, providing a web-based physical access control system (PACS) that is simple to install and use right out of the box.

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Wednesday, December 06, 2017

Ramp Generator - Triangle Wave Generator

Two questions on Ramp Generators -  I need a circuit design for a ramp generator. The ramp generator circuit that I'm looking for is a 1khz ramp generator capable of + to -50 v at 50m using a microprocessor with digital to analogue converter and output reconstruction filter followed by a high voltage operational amplifier.

The generator is going to be used for RFA (retarding field analysers) on plasmas.

Mail from MF of UK

I need a circuit design for a ramp generator. The ramp generator circuit that I'm looking for has put out a linear time varying positive voltage from 0 to +10 volts and needs a ramp time of 45 minutes. So from 0-10 volts in a 45 minute time frame. Maybe also a reset switch to reset the timer again. Can this be done? Please advise. Thank You

Mail from JA

Can you tell me in what application or how you plan to use it. Then i can probably help you better or make a circuit for you. there are many ways to do it. one is a constant current source charging a capacitor. or a staircase generator with a D-A and counter. send me more details.

4QD-TEC: Waveform generator circuits

This circuit was used as a ramp generator for a transistor curve tracer: the positive going ramp was used for testing NPN transistors and the negative ramp for testing PNP transistors.

Triangle Signal Generator

The first circuit produces a clean 2.5v reference voltage.  The second is configured as a classic multivibrator oscillator, whose frequency can be changed using a variable resistor.

Ramp Generator - Triangle Wave Generator

Precision Triangular-Wave Generator Uses a Single IC

"This application note outlines the implementation of a single-supply, triangular wave oscillator using the MAX9000 and some passive components. The application circuit uses an op amp, comparator, and a voltage reference as active building blocks. The MAX9000 is chosen because it integrates these three components. "

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Saturday, October 28, 2017

ECG EEG EMG bio-amplifier

i need to build a bio-amplifier capable of amplifying ecg, eeg & emg signals and displaying the corresponding waveforms on a computer monitor. the bio-amp has to be accompanied by a software program built using QBasic/QuickBasic. the bio-amp must use an rs232 serial interface port.

mail from AM


Study all these resources, that will help you with your project and learn the science.

Electrocardiogram (ECG) circuit

This application note makes use of a DrDAQ Oscilloscope / Data Logger to read and store electrocardiograms but this can be subsituted by any of the PicoScope range of oscilloscopes.

Electrocardiogram

A Portable, Low-Power, Wireless Two-Lead EKG System - PDF

Sensor devices (“motes”) which integrate an embedded microprocessor, low-power radio and a limited amount of storage have the potential to significantly enhance the provision of emergency medical care.

Zigbee- based Low- cost, Low- Power Wireless EKG

Electrocardiogram (EKG) monitoring is of prime importance in the medical world. Using the state of art technology to take it to a wireless platform can open up a broad spectrum of wireless medical devices.

ECG Monitor - Abstract - PDF
This project deals with an application of H3687 from Renesas H8 series of processors in the Medical field to record ECG.

PC based ECG Monitoring System
A project on creating and research the framework needed for building a PC based ECG monitoring system.

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