Thursday, January 24, 2019

Display ICL7107 - Temperature controller

This is the Display Circuit and PCB part of of section Temperature Control. Displays should be visible in moderate sunlight or factory lighting. Red Led displays are best for this type. Have a hood on the display area to avoid reflections.

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 ground/earth should be good to get a stable reading, the sensor connections should be sound. It is better to earth the metal DIN enclosure to make the device immune to EMI-RFI.

5 V Dual Supply with Zeners

A Steel DIN Enclosure may be difficult but can give your Industrial product Noise Immunity, Powder coating of the cabinet gives it some insulation and aesthetics too.

The PCB for above
The PDF Circuit for above Display Card STC1000 

The PCB copper tracks have to be tinned. Protection coating, masking must be good. Use RTV compound cover on completed PCB, for using in corrosive environments.

Wednesday, January 23, 2019

Tutorials for Electronics - Williamson Labs

These are simple and easy for learning, it is oriented towards practical electronics. It has a rich experience of Glen, who has seen the real electronics engineering as it evolved.

Tutorials for Electronics - Williamson Labs   Wayback Copy
  • Ergonomics
  • Elementary Electricity
  • Engineering NOTEBOOK
  • Intuitive Electronics
  • Design Flow Chart
  • Transmission Lines
  • Mixers & Modulation
Williamson Labs and The Laws of Glen

Engineer under Construction

School Should Emulate Industry: - The Project Oriented Approach: Enables the Learn by Doing Paradigm.

Glen is like the Murphy for Electronics Engineering. There has be a "Laws of Glen" one can digest and precipitate from his valuable writings.

Tuesday, January 22, 2019

Analog Electronic Circuit Design

The very first designs that came about were analog designs, a Vacuum Tube amplifier is an example. Analog is the representation of data or physical parameter in an accurate and precise decimal number like + 72.182 mV. The greater the resolution required, the more demanding is the design for achieving high accuracy and low drift. Digital circuits have only two voltage levels, high and low, the third state of floating, Hi-Z or high impedance is only for multiplexing or sharing a bus. This is done so that devices dont drive into each other and it is also used in external port drivers.

Analog Design and Circuits

As an analogy, see the conventional water tap as an analog control, an electric light ON-OFF switch as a digital control.

Bob Pease - Analog Guru

Among the semiconductor products Bob designed are temperature-voltage frequency converters used in groundbreaking medical research expeditions to Mt. Everest in the 1980s. He also designed a seismic pre-amplifier chip used to measure lunar ground tremors in the US Apollo moon landing missions. Among his more memorable designs are the LM331 voltage to frequency converter and the LM337 adjustable voltage regulator. - Remembering Bob Pease

Analog Circuits Instrumentation

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