Test-Measurement

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This is a Digital Panel Meter based on ICL7107. This was the workhorse Digital Readout chip before Low power uC designs were developed. Even now it is the easiest way an analog parameter can be displayed in an instrument.

Instrumentation and Measurement Circuits

3-1/2 Display is just enough resolution for recording process data or troubleshooting equipment. With 4-1/2 you notice the problems of thermoelectric EMF of probes and connectors. That is one reason gold plating is used another being low contact resistance. In 4 1/2 the reading can change due to contact resistance too, if the input impedance of the analog signal conditioning is low or the protection diodes, RC filter caps are leaky.

ICL7107 DPM Digital Panel Meter

When you measure an analog parameter from a sensor; you attenuate or amplify it, to scale to the A/D converter range. You also need to protect or isolate the analog front end from high energy mis-connections, which will happen during field use. The operator should not get injured from any high energy leakage while measuring.

Resolution is the finest detail you can enumerate in a parameter or object. You can say the crowd was 3000 or 4000 people. Here 1000 is the resolution, finer data does not matter here. You would also hear things like, there were 80 to 90 boys in that classroom. 10 is the resolution there.

Accuracy is how precise a statement or number is. If there was 85 boys in that class, the above statement is accurate. If there was 65 boys, the measuring method or process needs calibration or examination.

In this circuit, the plastic caps should be of very low leakage. Multilayer plastic caps are good for instrumentation.

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In: Instrumentation, Power Electronics

This is a Regulated 0-30 V DC Power Supply manufactured by me in small numbers, 0-30V 5A and 5V -5A. It had a Switching Preregulator. This keeps the Vce across Transistor Bank at the Back of Instrument, at the lowest possible level, in order to keep them Cool. When Vce and Ic both are more in a Power transistor it will get heated more, then the efficiency of power supply is low.

Power Supplies Section – delabs

Variable Regulated Power Supply

The Output had both Constant Current Control and Constant Voltage Control. The CC control is also a Short circuit protection. The Output was protected from outside voltages damaging output circuits even when equipment is switched off. The back panel is a finned anodized black aluminum heat sink with many transistors.

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The ICL8038 waveform generator is a monolithic integrated circuit capable of producing high accuracy sine, square, triangular, sawtooth and pulse waveforms with a minimum of external components. The frequency (or repetition rate) can be selected externally from 0.001Hz to more than 300kHz using either resistors or capacitors, and frequency modulation and sweeping can be accomplished with an external voltage…. The chip is available in some stores, not in production. (This is another chip of intersil i used for many things – delabs)

ICL8038 Device Information

  • Low Frequency Drift with Temperature 250ppm/oC
  • Low Distortion 1%(SineWave Output)
  • High Linearity 0.1%(Triangle Wave Output)
  • Wide Frequency Range 0.001Hz to 300kHz
  • Variable Duty Cycle 2%to 98%
  • High Level Outputs TTL to 28V
  • Simultaneous Sine, Square, and Triangle Wave Outputs
  • Easy to Use – Just a Handful of External Components Required

Everything You Always Wanted to Know About the ICL8038

ICL8038 Versatile Waveform Generator

Use in Phase Locked Loops – Its high frequency stability makes the ICL8038 an ideal building block for a phase locked loop as shown in Figure 9. In this application the remaining functional blocks, the phase detector and the amplifier, can be formed by a number of available ICs (e.g., MC4344, NE562).

The linearity of input sweep voltage versus output frequency can be significantly improved by using an op amp as shown in Figure 10.

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Any Tablet with an external Hardware can make a nice Instrument. The professional part lies in that external hardware and usability of the software or app. Windows Virtual Instrumentation are well known. Things like USB Scope and Data Loggers have been there for decades.

Now we have Android in which an Open Source product can be developed. The Open Source is both in Hardware and Software.

Android Virtual Instrumentation

See a android virtual instrument – OsciPrime is an Open Source Android high speed data acquisition hardware platform and Android oscilloscope application.

Open Source Android Oscilloscope

Virtual Instruments for Android has a nice future in Industrial, Automotive and Measurement areas. You could start by Interfacing with Bluetooth, USB and then move to IoT and WSN.

 Android OPC UA SCADA and Client

TeslaSCADA is a SCADA for accessing production and process data through smart phones and other Android devices, using the industrial communication standard – OPC Unified Architecture (UA).

These were some questions i got a few years back…

1 – If i had to create a crude “Lux Meter” and “db Meter” using the built-in camera and microphone on a Android Device – How would i Calibrate it ?

2 – Is there a Component(software) for Android to interlace with a Arduino Device as an external interface, This will help us make a DMM/Scope or even a Entire Lab Test bench centered around a Tablet and a Plug-in Mini Instrument Rack.

Both Sound or db Meters and Lux or Light Level Meters are in the Google Play nut need calibration. All These Instrument Needs a USB/Bluetooth Sensors.

Add Bluetooth you can carry your Tablet away from the instrument probing the DUT. (Device under Test)