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Monday, December 15, 2014

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.

    Thursday, December 11, 2014

    Computer Data Interface - delabs

    The PC is now an economic and common equipment at home or office. Due to Open source and GNU Linux, many professional programs and environments are easily accessible. To interface it to the real world is a step in learning Automation and Robotics.

    Computer Data Interface - delabs

    Computer Data Interface - delabs

    In Automation we have both Industrial and Home. You can start with home automation, as industrial automation is more complex. But in Home Automation, Safety First should be emphasized, Any neglect in care of electrical hazards will neutralize any advantage of Home Automation.

    Printer Port

    Do not apply voltage above 5V to any pin of printer port, ensure earthing is good, use opto couplers for inputs and outputs if you are not sure. wrong use will damage motherboard, these circuits should be used only if your basics are very sound.

    delabs Technologies 16:16 30-Mar-07

    Analog Interface for PC Ports.
    Control Interface to PC Ports.
    Project Source - virtual-instrumentation - Examples of Computer Interface to Instruments

    Monday, December 08, 2014

    delabs Design Service and Custom Projects

    Some old examples of open custom designs. these were made to educate the customer and also study the capability  of online communication and and collaboration tools for such activity.
    Two Stage Sequential Timer Docs - 

    The circuit is a two stage sequential timer with auto reset. It can turn a Solenoid On/Off after a Sequence of delays that are preset. This is also a basic example of timer usage in automation.

    Design Documents
    All Timers are 1 - 30 Secs Analog with Presets to adjust with a screwdriver. The Switch, Solenoids and Power supply has to be via terminal blocks or plug-jacks. The PCB may be upto six Square Inches for standard DIP components but with SMD it may be smaller.

    delabs Design Service and Custom Projects

    Four Channel Temperature Alarm Docs

    The temperature in a pipe is monitored with four RTD Pt-100 Sensors, The type of probe could be Extruder RTD probes with Bayonet or Compression Fitting, Get it from Omega. To keep costs low you can choose small thin film RTD sensors, they will be fast but on rough usage may break.

    Design Documents
    The time taken to measure the temperature at the 4 points will be less than 4 seconds. An optional display of the measured temperature as shown above can be avoided by using a DMM to adjust the setpoint.

    The Analog Timer Module can be set from 0- 30 minutes. If out-a remains high even after set time a out-b alarm goes on to sound a buzzer and flash a LED light.