This is the RTD Signal Amplifier part of Temperature Controller or Indicator. The card also contains a relay on-off control circuit.
The Circuits are -
The PCB Boards -
This is the pcb board details of a Two Set Point Controllers for any process, shown here for temperature. For new types of transducers or input types, module card has to be designed or modified. The other cards remain the same. The cabinet of these process controllers were made of steel for shielding, but the display card would still pickup EMI in some cases. These were more in instances where the Instrument supply was derived from the motor 3-phase supply. Instrumentation Supplies 230V AC must come from a Lighting Circuit of another supply arm, this has to come after conditioning Read More …
When you need a proportional control output, either 4-20mA or Time Proportional On-Off, This module is used. It does a slow PWM control, the cycle time for SSR or Thyristor Banks can be closer to Mains Frequency. The 4-20mA can be used to drive motors for turning valves for fuel or fluid heat control. Schematics of Module Proportional Control Card Two Set Point Card Proportional Control Card 4-20 mA Board of Module Proportional Module Copper Proportional Module Solder Mask Proportional Module Silk Screen Proportional Module Drill Template
This module converts J, K Thermocouple and 4-20 mA Inputs to 0-2V Full Scale. These can be used for any voltage input too. The RTD module can be modified more easily for Voltage inputs. The control output can be On-Off or 4-20 mA/Proportional with another card. The 4-20mA I/O STC1000I is not complete. Schematics of Modules J and K TC Module J-K Proportional Type 4-20mA In-Out Module Board of Module JK-I Module Copper JK-I Module Solder Mask JK-I Module Silk Screen JK-I Module Drill Template
This contains the Main card with a Power Supply and Relay Control. On this card is connected the Display ICL7107 – Temperature controller. The Thermocouple and Control Modules can be plugged into this card, these change the type of control and type of inputs. This way this can be made into any parameter controller with any type of input and output. But it is all set in production, not configurable at site. So even if you make a 4-20mA output Flow Controller with this, the Main card and Display card remains the same. Only the Modules change. No Connectors are Read More …
This is the Display Circuit and PCB part of of section Temperature Control. The above circuit is powered by +5 and -5 from a LM7805 and LM7905 pair. If +/- 12V or +/- 7.5V is used in opamp or digital parts, then use below circuit for the DPM section. The PCB for above TC Display Copper Side TC Display Silk Screen TC Display Solder Mask TC Display Drill Template The PDF Circuit for above Display Card STC1000
This is a Low cost controller, Analog Dial Temperature Controller. It is also called Blind Controller. This essentially means Open Loop, just control the fuel or energy input to the system to regulate heat. This is not a Blind Controller that way, it only cannot display the temperature value, that could be another reason it is called blind. Dial cyclic timers were used to control heat, these were purely mechanical clockwork devices. They could regulate well, when the material flow (liquid) is constant and mains power is regulated. But when the job to be heated, varies in quantity, control temperature Read More …