Friday, May 11, 2018

Instrumentation and Automation - 01

Here are some Test and measurement notes. These ideas come from practical experience. But the jots are not in any order but are quite important.

DuMont Lab Oscilloscope

Scope Notes
  • If the waveform on the scope droops then you may need to use a 10X attenuating probe or mode. this attenuator is at the tip of the probe hence better measurement possible, also very high frequency signals may be best transmitted over a 50 ohm impedance matched line to the Oscilloscope. 
  • Karl Ferdinand Braun - In 1897 he built the first cathode-ray tube...oscilloscope. CRT technology is to this day used by most television sets and computer monitors. The CRT is still called the "Braun tube".
  • Do not use an oscilloscope to measure 230V directly, use a transformer, differential probe or attenuator.
  • An oscilloscope 1M probe or a DMM 10M impedance can load circuits with nano-pico amps of bias.

DMM Notes
  • Test a NPN transistor, DMM in 200K range. emitter negative probe, collector positive probe, it should show open. while still holding that way press wet finger on base and collector, it may show some reading, then it is ok. for PNP swap probes polarity and do the same thing. the wet finger when pressed applies a base current in uA.
  • The most common reason of DMM failure is when a person tries to measure 230V AC with a DMM in current or ohms mode, with the probes in the wrong sockets. Use external attenuators and shunts.
  • A DMM in diode mode or resistance mode can be used to test IR diodes, take it under 100W lamp and measure, cover the IR diode and measure you will see a response in proper polarity.
  • If you put the DMM in 2V mode and measure the voltage across a ordinary LED near a 40W lamp you will see around 200mV. Turn off 40W lamp the mV will fall near 0. Even metal-can transistors with their top ground away will become photo sensors.
  • When you measure low voltages or high resistance like 1M with a DMM your body must not be in contact with the probe tips. Body resistance is low in comparison so error in reading or loading of mV from sensor, in sensitive and high impedance ranges.
  • Red socket and probe for positive and black socket and probe for negative
  • Is it oscillating ?.... We cannot say, it could also be DC, you need to see if a Clock is present. use a signal tracer or a DMM freq mode, or AC measurement. or build this solorb.com-elect-logprobe. When you do not have a scope you can build one for the PC.
  • Polarity and Zero Cross indicators tell you to swap the leads. Use a comparator or opamp to build it.

Monday, May 07, 2018

Multi Zone Process Monitor

Here is an ancestor of the product in the earlier post. It is a Process Scanner and Indicator. There was no control, but there were individual alarms for each channel.

Multi Zone Process Monitor

This is a original design of mine, obsolete now due to size and technology. The inspiration of the product concept was from a Omega Catalog Item. Even today i use the Omega catalog for inspiration, but i do not design complete products, only circuit sections.

Read more about Control Instruments at my pages here

Thursday, May 03, 2018

EE and Computer Online Learning - MIT

Free Online Course Materials for EE and Computers. Here are resources useful for the EE Students and Teachers. These are at MIT and they are available for all. It is a OpenCourseWare (free).

Electrical Engineering and Computer Science at MIT

"MIT has awarded electrical engineering degrees for nearly 130 years, and our educational programs have been at the cutting edge since their inception. We provide an in-depth education in engineering principles built on mathematics, computation, and the physical and life sciences, and encourage our students to apply what they learn through projects, internships, and research. "

EE and Computer Online Learning - MIT

delabs Notes

Students can enhance their learning even at home after the classes using these materials. This will help you grasp what happens in the college the next day.

It is also important to keep yourself physically fit. Some jogging, swimming, cycling and light workout will even strengthen the nervous system.

I would not like to write this here, but i have to. My own experience. Do not build muscles for looks or abnormal growths. Some use hormones, over exercise and even some medicines for artificial growth. At a later age it causes lot of problems due to accelerated aging. Even athletes should refrain from these for the long term interest of their health.

Contents

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


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


Hobby Circuits
VU Meter Circuits
LED brightness control
555 Incredible Chip
Process Control
liquid level measurement
Thermocouples and RTD
Design ADC Interface uC
Thermocouple Amplifier
IA Instrumentation 02
Temperature on DMM
Optical Proximity Switch
Analog Mux - Data Acquisition


Test Measurement
Instrumentation Automation
NI Test and Measurement
DMM Digital Multi Meter
Oscilloscope in T&M
IA Automation 01
Build Instruments
Tektronix T&M Equipment
Educators Corner – Agilent


Power Electronics
UPS Background
Transformer Connections
DN Power Electronics 03
DN Power Electronics 02
Half Bridge Convertor SG3525


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

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

Tutor Gadgets
Count-Up Timer
Digital Logic Gates
Electronics Tutors

History
Teaching Instruments
Charles Proteus Steinmetz
Muntzing a Circuit Design
Teralab Electronics projects
Historical Instruments


Tables, Charts, Videos
Binary and Hex
Resistor Color Code
Ohms Law
Giga, Tera, Pico, Nano
High Resistance Materials

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

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