Monday, December 26, 2011

The basics of control system design - George Ellis

Embedded Systems Design - Embedded.com


Reading the excellent articles above, i was reminded of an incident....

Proportional Controllers not only save energy, they can give a controlled finish or treatment to a job. An on-off controller or thermostat limit protection has to be used in series, this is to to stop a Runaway Process.

There was a real life instance when a Temperature cycling oven maker (environment chamber), faced large liabilities as an 8086 based profile controller and chart recorder just locked up and all the electronic equipment were roasted. Here even a bimetallic thermostat would have saved the day. Nowadays we have a watchdog timer to prevent such uP mishaps, but still use an analog controller in series as an over temperature trip. - Ananth


Tuesday, December 20, 2011

Interface a PC to Measure or Control Temperature

How to Use Your PC to Measure Temperature

Thermocouple, RTD, Temperature monitoring is central to the majority of data acquisition systems, be it to save energy costs, increase safety, reduce testing time…whatever your reasons, you will need a device to measure the temperature - a temperature sensor.

How to Use Your PC to Measure Temperature

Thermocouples, resistance temperature devices (RTDs), thermistors and infrared thermometers are all types of temperature sensor. Which you choose depends on factors like your expected maximum and minimum temperatures, the accuracy you need and your environmental conditions.

752-RTD: RTD Resistance Temperature Measurement, Digital I/O, Counting, Analog Output

  • Measure temperature using RTDs or Pt100 sensors, and voltage signals
  • With extra hardware monitor thermocouples and strain gauge bridges
  • Includes the powerful yet easy-to-use Windmill software for Windows: no programming required
  • Connect up to 8 USB units to one PC

Here is a way you can learn, How To Interface PC to the Outside World.

Temperature Control with a PC

This is a project that will help students learn both hardware and software aspects of a control system. Here you can test out an automation program on a PC with minimum external hardware.

When you implement in the field, the system has to be a dedicated real time uC based product on custom firmware. Systems with OS + Software combination are not known to be reliable in Process Control. But OS + Software is good for Supervisory Systems which get their data from Real Time Controllers.

So a front end controller must be Rugged, Non-PC based and Non-OS based unit. This means use something like Arduino. With a Robust and Compact (means fast) firmware.

The firmware should be Polling or Interrupt based but with both internal and external watchdog. Most important a Power supply Management that resets system properly over Brown-outs and Black-outs. Even today some Embedded Systems i have to turn off and on after power resumes.

Don't Forget, Multiple Watch Dogs and Multiple Power Management for graceful start of system !! Use one big SuperCap if you want. Else people will go back to Thermostats.

Thursday, November 03, 2011

EE Books of Hans Camenzind

Hans Camenzind book on Analog CMOS design is a good reference for students and covers Power Electronic concepts like Switching Regulators and Low Drop-Out Regulators. Designing Analog Chips by Hans Camenzind

The Delta-Sigma Converter A/D and Zero-Crossing Detectors on Mixed Design.

Communications circuits like Timers and Oscillators . Phase-Locked Loops and Filters too.

Designing Analog Chips by Hans Camenzind

Hans Camenzind was born and raised in Switzerland and moved to the U.S. after college. He received an MSEE from Northeastern University and an MBA from the University of Santa Clara. After several years doing research in the Boston area, he moved to the West Coast to join Signetics (now Philips) and later started his own company, Interdesign. After heading it for seven years he sold Interdesign to Plessey.

See - Much Ado About Almost Nothing

Monday, October 24, 2011

Earthing Practice by Trevor Charlton

Earthing Practice by Trevor Charlton

  • Methods of Earthing Power Quality E-library
  • Earth Conductors
  • Electrical interference
  • Lightning Protection

Power Quality and Utilisation Guide

The PQ E-library is a collection of electronic technical reference documents covering introduction, costs, harmonics, resilience, voltage disturbances, earthing, energy efficiency and renewables/distributed generation

Copper Development Association

  • Educational Resources
  • Computers cannot work without copper
  • Electricity in buildings

Copper Development Association Website for information on Copper and Copper Alloys

Also See- Good Earthing Prevents Shocks

Contents

Tables, Charts, Videos

Binary and Hex
Resistor Color Code
Ohms Law
Giga, Tera, Pico, Nano
Milliamp Meter
Thumbwheel Switch
High Resistance Materials

Analog

School - Analog Design
DN Analog Basics 06
DN Op-Amps 01
TI Semiconductors

Process Control

liquid level measurement
Thermocouples and RTD
Design ADC Interface uC
Thermocouple Amplifier
IA Instrumentation 02
Temperature on DMM

Test Measurement

Instrumentation Automation
NI Test and Measurement
DMM Digital Multi Meter
Oscilloscope in T&M
IA Automation 01
Build Instruments

Components

Good Voltage Regulators
Relays and Contactors
Potentiometers Trimpots
Prototype Boards Types
Types of Capacitors
Types of Switches
Resistors How they Work
Coils Transformers SMPS
Mains Transformers Types
DN Components Selection 05

Hobby Circuits

VU Meter Circuits
LED brightness control
555 Incredible Chip

Basic Electronics

Basics of Electronics
Product Production
Work Discipline
Testing Points
Learning Electronics
Electronics Theory

Production Notes

Prototype Fabrication
Electrical Circuits
Electromechanical

Library

Scots Guide Electronics
Engineering - Wikibooks
Design Lab - Jim Svoboda
DC Circuits UOG
Socratic Electronics
Blobz Guide Electric Circuits

Power Electronics

UPS Background
Transformer Connections
DN Power Electronics 03
DN Power Electronics 02

Embedded

Interfacing Microcontrollers
Embedded Process Control
80C31 8052 Microcontroller
Microprocessors and uC
Embedded Systems Design

History

Edison Phonograph
Miami Museum
Teaching Instruments
Charles Proteus Steinmetz
Muntzing a Circuit Design
Magic Eye Valve Tube
Teralab Electronics projects
Historical Instruments

Product Design

Product Development
Constant Current Source
Good Voltage Regulators
Insulation Resistance
Digital Insulation Tester
DN Schematic PCB 04
DN Product Design 07

Tutor Gadgets

Count-Up Timer
Digital Logic Gates
Electronics Tutors

Science

Delsea Physics Page
Science Toys
Science Clips
HyperPhysics
FCC Kids Zone