Thursday, November 20, 2014

Thermocouple and Pt-100 RTD

The easiest way to measure temperature is with a glass diode like 1N4148 or a metal Transistor like 2N2222. These have a small temperature range, probably -5 to +120 is possible, but non-linear. A copper coil or any metal wire or even a wirewound resistor can work as temperature sensor but the thermal inertia makes it sluggish. IC semiconductor based sensors like LM335 and AD590 are easy to work with and pretty accurate. In industrial environment many types of Thermocouples, Pt-100 RTD and Optical Infra-Red Temperature measurements are used.

Input Levels for Thermocouples and RTD Pt-100. And the ways it has to be used. Thermocouples are selected on the basis on how they are mounted or fixed, the environment, the temperature range that is measured and finally the price you can afford for a particular application. Sometimes mechanical wear or chemical environments may eat away the sensors, so a cost-effective solution has to be evolved.

One customer wanted a special Pt-PtRh very high temperature sensor for molten aluminum. It was very difficult and costly to even arrive at a solution. So a non-contact infra-red sensor may save lot of time-money and even reduce risk of injury.

Thermocouples and RTD Tables

For J, K, and T Thermocouple Read "Temperature" + Room Temperature for mV shown applied to equipment, eg....

If Room Temperature is 25 Deg C and mv applied is 10.777 for J Type STC1000 then reading should be 200 + RT = 225 deg C. The mV shown are for Reference Junction at 0 Deg C.

It would be better if you refer links below, The above table i made long ago, then a Scan with OCR later formatting. It could have errors.

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Friday, November 14, 2014

Engineering Management Equations

Call it Quotes or Ideas or Instructions, these are thoughts that came from me from the past tech experiences of over twenty years.

Technologies should scale with Infrastructure. Buildings cannot stress the Foundations meant for. Traffic proportional to Road Width. Sync. Software should not overwhelm or Overload Hardware.

Raw Materials - Components - Finished Products. The Entire Processing and Design Chain has to improve, if the final Product has to Shine.

Management of Engineering and Technology

Value Engineering
In Engineering High Value products are those that are a combination of Precision Mechanical + Electrical + Analog + Embedded Microcontroller.

Tools Theory Practice
Excellent Tools alone are not enough, The Techniques & Methods have to be learnt, Then the Skills have to be acquired by Strenuous Practice.

Software 7S
The 7S - Software Should be - Simple, Stable, Spry, Slim, Scalable, Sensible, Scrimping.

Incremental Coding
I do incremental coding - code few lines, test, code again, test. Some extra code to interface for test inputs/outputs (virtual instrument). Incremental Coding, Modular. Test Points.

An Engineered Equation
( technologies + skills + processes ) X ( monitored + managed ) = engineering.

Keep Designs Simple
Circuit or Code - Keep it Simple, Modular, Reusable, Documented, Controlled, Compact, Clear, Creative, Maintainable, Testable, Tunable.

Tuesday, November 11, 2014

Inverting Amplifier - Op-Amp Designs

This is an Op-Amp Tutorial. Here you see an Operational Amplifier in the Inverting Amp configuration. I have used OP07 as it is almost like an ideal Opamp. The ultra low offset is the best part. Then not really, CA3140 has a Tera Ohm Input resistance but offset not the best. ICL7650 approaches an Ideal Op-Amp and chopper stabilized.

Inverting Amplifier - Op-Amp Designs

These parameters are good for DC Amps. Sensors, Strain Gauge Bridges Signal Conditioning need them. Then when you want a better AC performance, you can use a LF353 with a nice slew rate. Here the DC merits are not of much use.

Inverting Amplifier - Op-Amp Designs

Input Impedance of this module is Ri as pin 2 is at virtual ground, the opamp with feedback tries to maintain pin 2 and 3 at same potential pin 3 is at 0V hence pin 2 is at virtual ground. Clamping diodes protect OpAmp, Rf + Ri is between 5kE and 1ME as an opamp may be able to drive around say 5mA max

Inverting Op-Amp Tutorial xml code

Friday, November 07, 2014

Buffer Unity Gain Amp - Op-Amp Designs

If output impedance of a point is a high value then connecting another circuit at that point will load it, resulting in malfunction or error. Buffers are used as interface between circuits.

Low impedance of an output means it can source/sink lot of current, when you need 2 opamps use LF353 or TL072 which are dual opamps.

Buffer Unity Gain Amp - dapj Tech Widgets

Buffer Unity Gain Amp - Op-Amp Designs

A non-inv FET input is the best buffer, for inverting buffer use high R values. Using very high R values like 2.2M or higher requires a glass epoxy PCB and guard rings around pin 2, 3 to prevent leakage currents on the PCB reaching the PINs.

Also moisture and dust has to be prevented by using RTV coating or Varnish. Use 78L05 and 79L05 for the dual supply required by this circuit.

Buffer Unity Gain Op-Amp Tutorial xml code

Tuesday, November 04, 2014

Electronic and Instrumentation Tables

Tables, charts, quick reference cards, booklets and handbooks; are the most versatile tools of learning and putting the learning into applications. These should not have a lot of language or flowing text. These are - to the point, easy to remember, graphical, colorful (memory aid).

Electronic Tables and Charts

Electronic and Instrumentation Tables

Just like a circuit diagram, flow chart or ladder logic can graphically interface with a human mind, Tables and Charts easily embed into ones memory.

Monday, November 03, 2014

Virtual Oscilloscope - Visualize Equations

Oscilloscope Functions and Fourier Series. Periodic Waveforms. Watch Sine, Square, Triangle and Sawtooth Waves and Study Controls. This Scope is a Real Time Graph of Volts Y and Time X at any node of a circuit. It can show both AC and DC.

Virtual Oscilloscope - Visualize Equations

Load an equation of your own and see it as a waveform on this web scope. Paste a Formula in the Equation text box, load it, it will be rendered as waveform on scope. Learn from this page ....

Virtual Oscilloscope - Visualize Equations

JS Oscilloscope xml code

Just turn it on and then press demo button for 1st Waveform and Press again the demo button for 2nd Wave and so on. Still working on formulas. Slide all the pots and see what happens.

digital-oscilloscope - An Oscilloscope Simulation using CSS and JavaScript

Related Oscilloscope Information