These are the circuits and boards of a Mini Temperature Transmitter for a Platinum hundred ohms temperature Sensor.
The customer wanted a two wire system, this needs low power opamps which were ten times the price. If this transmitter works at 3mA it could have been two wire. Those parts were in short supply and the budget of customer was low. So i made it with regular opamps but three wire. The customer was satisfied as he got a cost effective solution. But now the situation of markets and products are different.
RTD Three Wire Transmitter
If you need to transmit the temperature from a high voltage area or toxic environment. You will need to hermetically seal the transmitters, convert the Voltage to frequency, frequency to IR LED flashes or RF. This can be then remotely monitored. Then the transmitter has to be battery-solar operated, low power too. ICL7135 is a simple solution. It has a serial output that can be used to Drive IR Leds. Remotely sense these flashes in a Micro-controller and you have a reading. You may be able to use optic-fibers too. Where volatile liquids are present so that the risks of sparks can be eliminated.
More at Process Control Circuits
This is the same Mini RTD Pt-100 Transmitter but in its case. Encapsulated in epoxy, hermetically sealed against harsh industrial environment. This will work well even near fumes of Ammonia with no corrosion. But not near vapors which can be ignited by sparking as terminals are still open. The side view shows zero and full scale ten turn bourns trimpots heads, for calibration. After cal it can be sealed with RTV compound.
Automation and Control is the predecessor of Robotics. A Jump Start, Practical and standard reference for Process Control is at at Omega Technical Reference.
A Control system is made of Sensors sending acquired data to a Controller which operates Actuators to manage the process in Real Time. Starting from a Bimetal Thermostat to a SCADA, the controller has grown from mechanical — electrical — analog — digital devices to microcontroller-computer based equipment.
Both in Control Systems and Robotics the Collaboration between Robots or Control Units, leads to the development of wireless network of Interactive, Intelligent and Distributed Self Governing Systems. The outcome is Web Process Automation, Web Applications based Solutions in Monitoring, Analyzing and Configuring these Sophisticated Networked Systems.
Read More at my – Industrial Process Control Applications
This is a RTD Pt-100 Transmitter, It can Convert Thermocouple mV or RTD mV to 4-20 mA Current Transmitter. The part numbers on Circuit and silk screen may not match. But the PCB may be usable. The output is a current source and not a current sink. It goes to a 4-20mA Mux with a common ground. The Circuit RTD-Pt-100-Transmitter Circuit.
This low-cost transmitter was made to send RTD information in a 4-20mA over long distance. The 4-20mA was the input to a Analog-Mux which interfaced to a GE-Fanuc PLC system and a 486 Computer. The Analog Multiplexer Built around CD4051 was was controlled by PLC to get data from numerous channels. This reduced the cost of the System. This is ok when Real-Time Acquisition is not required. The Analog 4-20 to 4-20 Mux-Buffer circuit can be seen at Industrial Process Control Circuits.
This was done as customer budget could not afford dedicated analog input modules for every channel. There were more than 50 Inputs. The thermal inertia of system did not need a real time or fast correction.
The PNGs of PCB is 600dpi 16 color. It is to be scaled appropriately.
CAN (Controller Area Network) is a serial bus system, which was originally developed for automotive applications in the early 1980’s. The CAN protocol was internationally standardized in 1993 as ISO 11898-1 and comprises the data link layer of the seven layer ISO/OSI reference model.
CAN Controller Area Network in Automation
CANopen is a CAN-based higher layer protocol. It was developed as a standardized embedded network with highly flexible configuration capabilities.
In the year 1992, several companies founded the CAN in Automation (CiA) non-profit group, in order to provide technical, product and marketing information.
CANopen-based dust-filtering systems
Hesch (Germany) has developed an industrial dust-filtering systems. The HE 5750 host-controller provides a CANopen NMT master interface to communicate to the sub-layered valve units operating the dust-filters. The entire system can be controlled by means of the Profibus or Modbus interfaces. The embedded filter control software supports the reduction of emission values and energy costs.
The valve controllers are uses to pulse solenoid valves in industrial dust extraction technology. They are controlled via an embedded CANopen network by means of the HE 5750 host-controller. The NMT slave units are attributed locally and technically to one filter chamber each. This concept adapts to any desired number of filter chambers and valves.
CAN in Automation (CiA)
Kontumazgarten 3 DE-90429 Nuremberg, Germany.
This was one unique custom design i made for a Mining Company for Ore Processing. It was Multi Zone Scanner controller.
It might have been for a rotary kiln of a large size. Four temperature sensors were connected to the system with brushes just like in a motor. Even the supply to the trasmitters was on the brushes.
The Instrument had a Analog Multiplexer with a Synchronous Sample and hold, as the analog value was coming via the brushes. It had four relays that would turn off or on every scan cycle, depending on the input values. The kiln system was slow it had inertia, so it did not require a fast acquisition for ‘Real time’ as you may find necessary in small Thermal Systems.
This was built with analog and digital chips, no uC in this design. This was because it was a front end controller, there was a risk of a uC system getting stuck. These days, that problem may not be so worrisome, but i am not so sure.
What if the watchdog goes for a short nap?
You can find part of the designs here – Industrial Process Control Circuits
Hitachi is a highly diversified company with products and solutions in High Functional Materials & Components, Power Systems, Electronic Systems & Equipment, Automotive Systems, Digital Media…
Hitachi – Engineering and Technologies
Hitachi was founded in 1910 by electrical engineer Namihei Odaira. The company’s first product was Japan’s first 5-horsepower electric induction motor, initially developed for use in copper mining. Odaira’s company soon became the domestic leader in electric motors and electric power industry infrastructure
Hitachi J100 adjustable and Variable frequency drive. Photographed by C J Cowie
Hitachi at Wikipedia
Hitachi has contributed immensely to semiconductor and electronic manufacturing technologies.
- 1958 Completed six-transistor miniature portable radio
- 1959 Completed electronic computers based on transistors
- 1966 Developed LTP processing technique for silicon transistors
- 1978 Experimental color camera with solid-state miniature image device developed
1976 Hitachi portable VTR, for Sony 1″ type C; the source and take-up reels are stacked for compactness.
HITACHI 1 Zoll-C-Maschine – Video tape recorder
Siemens is one of the world’s largest technology companies. Siemens has six major business divisions: Communication and Information, Automation and Control, Power Generation, Transmission and Distribution, Transportation and Automotive, Medical, and Lighting.
Siemens – Industrial Technology
Siemens & Halske was founded by Werner von Siemens and Johann Georg Halske on 12 October 1847. Based on the telegraph, his invention used a needle to point to the sequence of letters, instead of using Morse code. The company, then called Telegraphen-Bauanstalt von Siemens & Halske, opened its first workshop on October 12. – Wikipedia – Siemens
Analog Integrated Circuits 1976 – Siemens
In 1999, Siemens’ semiconductor operations were spun off into a new company called Infineon Technologies.
In 1881, a Siemens AC Alternator driven by a watermill was used to power the world’s first electric street lighting in the town of Godalming, United Kingdom.
Siemens Console 1988
Siemens Industry Automation and Drives
Complete and integrated line of products, systems and solutions for production and process automation. Customized automation solutions based on Totally Integrated Automation (TIA) and Totally Integrated Power (TIP).