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Sunday, February 02, 2020

Analog Op-Amp Circuits

Operational Amplifiers - With a few Op-Amps and a regulated Power supply, many Instrumentation and Process control equipment can be designed. The Human Brain understands Numbers, Quantity and it regulation very well ! On the right you can see a analog controller based on opamps and discrete devices. A Heater, Fan and Motor is regulated, controlled and timed for a process.

Analog Op-Amp Circuits

Analog is about numbers, the circuits can be understood and designed mathematically or empirically. Designing and Building a True RMS Rectifier with Op-Amps, will help a designer digest many Op-Amp capabilities.

Analog Op-Amp Circuits

Things you ought to know about Op-Amps -

OpAmp part numbers from various semiconductor companies are designed for both General purpose and special applications. Some have to be cost-effective for consumer low-cost equipment, while others may be advanced in specs, closing in on an ideal Op-Amp.
Instrumentation opamps are used for accurate and low drift applications. These Op-Amps have stringent specifications and are used in the fields like Aerospace or Medical Electronics. A pre-amplifier for an FM Radio may need to be low-priced. Test Measurement needs Op-Amps which have near ideal specs in the area of measurement or application. CMOS low-power devices are used when designs are made for portable gadgets.
  • Outputs cannot be Loaded beyond the drive capacities, Note Resistors and Output Load.
  • Inputs draw a small bias current and will load the signal sources, compensate design.
  • Op-Ams AF-RF or Switching performance study with Slew rate and Bandwidth.
  • Power consumption of some Op-Amps are more and some very less, choose wisely.
  • Look for Standard Pin-Outs, Price, Popularity and study Abs. Max, AC and DC Specs.
  • Use Packages with multiple Op-Amps like LM324 to save board space and assembly time.
  • Op-Amps and its 1% MFR resistors should have a separate supply and far from hot parts.
  • Ultra Low Offset Voltage is required, when you wish to amplify a DC level of say 500uV.
  • Guard rings to be used for High impedance inputs and EMI-RFI Shielding for AF Amplifiers.
  • Glass epoxy PCB, clean surface, Pins and Tracks protected from Moisture and Chemicals.
  • Avoid Ground Loops, Have regulated Low ripple Power supplies. Dynamic Isolation.
delabs Technologies

Process Control Circuits for Automation

These are the circuits and boards of a Mini Temperature Transmitter for a Platinum hundred ohms temperature Sensor.

Industrial Process Control Circuits

Analog Design in Process Control is seen at the Sensor Signal Conditioning Stage. Controllers also use Opamps for Analog Computation Tasks. These are Real Time in the Truest Sense.

Process Control Circuits for Automation

A closed loop controller is the heart of an Industrial Automation System. Right from an On-Off Hysteresis Controller to a Auto Tune PID Controller, we find solutions of different complexities. Each solution might suit a particular system; depending on the requirements of Ease-of-use, Cost and Process Type.

Circuits in process control
Even today, the controllers at every stage of evolution, from the thermostat to Auto-Tune, are used in many countries, for many different industrial applications. No solution above is obsolete! The developing Countries still use electro-mechanical or semi-automatic means for control in some areas. and Process Type.

Closed Loop Control Systems

A Closed Loop Control System is the most important aspect of Maintenance, Regulation and Stability in any Live Process. Nature itself is self regulated in an intricate fashion, a keen observer can notice the subtle controls. In Human Created Industrial systems we have Process control as a complex science. We can start by understanding a Simple One.

Process Control Application Notes

When you fill a Bucket with water, You keep an eye on the Level of water, as you open the Analog Tap, which is an equivalent of a Motor operated Valve. Your Eye is an advanced Optical Sensor, which is able to sense the level by the computation in the brain, which in turn operates the muscles of your hand, thru the nervous system. The hand along with the Water Tap is is the Actuator. As the water fills up close to the top, you start reduction of the water flow and keep observing, then as it tops up, you tweak the tap to a trickle. When it reaches the limit you shut off the tap.

Closed Loop Control Systems

While you are half way filling the bucket, what happens if you take a short nap, or a friend comes by and you are get absorbed in conversation, the water overflows and goes waste. Then someone raises an alarm after the Runaway process happens. This is of minor consequence, but it is not so in the case of Temperature, Pressure and also many common systems like the driving of an Automobile. Remember the gears, brakes, accelerator to control and steer the car to the correct destination, a Runaway Process causes an accident.

Extra Extra !