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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 [...]

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 [...]

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 [...]

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 [...]

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 -

RTD and V/I Module Propotional Output
RTD and Control Module ON-OFF

The PCB Boards -

RTD Module Copper
RTD Module Solder Mask
RTD Module Silk Screen
RTD Module Drill Template

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 [...]