delabs Circuits

Tuesday, March 10, 2009

Temperature Controller Main Card

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 used, to make it vibration resistant.

The PCB Layout is here

Display ICL7107 - Temperature controller

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.

5 V Dual Supply with Zeners

The PCB for above

The PDF Circuit for above Display Card STC1000

Sunday, March 01, 2009

Millivolt Source with Digital Potentiometer

Here is a Millivolt Source i built for Calibration in the early days. It uses only CMOS Digital and Mixed Chips from Intersil and CD40xx Series.

Digital Potentiometer - del50003

In this Circuit, digital potentiometer, connect pushbutton switches to fast and slow with one end to +7.5V, when you hold the button down the analog voltage will ramp up-down, fast or slow, this will enable you to make a digitally controlled millivolt source or power supply.

Millivolt Source

Later i tried a unit with 8748 part of the code in my uC section. This is with Ramp-up and Ramp-down using only two buttons. This works even now, The support below is an HRC Fuse Holder made of Phenolic or Epoxy Resin. The mV Terminations are on Top.

80C39-8749 MCS-48 Examples and code

This was supposed to have Analog in and Analog out. Some parts of the circuit may be in the 80C51 page. This has ramp-up and ramp-down settings for the Increment and Decrement buttons. This helps setting setpoint quickly. There is also debouncing for the pushbutton.

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VU Meter Circuits
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555 Incredible Chip
Process Control
liquid level measurement
Thermocouples and RTD
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Thermocouple Amplifier
IA Instrumentation 02
Temperature on DMM
Optical Proximity Switch
Analog Mux - Data Acquisition


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