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.
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.
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.
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)
Utility of Testing and Troubleshooting Tools : The first thing in Electrical testing is the Continuity Tester, Then we use the Neon Mains Screwdriver, Then we need an Voltmeter or an Ammeter. In electronics we need a OhmMeter and LCR meter too.
Many times we cannot carry big or expensive test instruments to the field, so we have to have a troubleshooting tool kit. Continuity testers, Logic Probes, DMM, Clamp Meters etc..
Simple Test Equipment
It also is sometimes required to build a quick jig or fixture with electronics to troubleshoot, simulate a problem or to test the reliability or aging of components and systems. Here you need to be cost effective, fast and innovative; and build a simple system with available, affordable or procurable resources. Hence a bit of circuit design, firmware and software are essential skills for production engineering.
Small Electronic Testing Tools
You can troubleshoot and repair Electronic Equipment easily with Meters and Continuity Testers.
Small Electronic Testing Tools – delabs
Regardless of experience, engineers and scientists can rapidly and cost-effectively interface with measurement and control hardware, analyze data, share results, and distribute systems.
NI LabVIEW – Virtual Instrumentation
LabVIEW is a graphical programming platform that helps engineers scale from design to test and from small to large systems
- Tight integration with a wide range of measurement hardware
- Easy-to-use graphical development environment
- Extensive signal processing, analysis, and math functionality
- Rapid user interface development for displaying live data
- Multiple communication options (TCP/IP, UDP, serial, and more)
The LabVIEW Platform, Part II
LabVIEW is an open development platform that has gained acceptance in many different application areas and industries. Why? At its core, the LabVIEW graphical programming language has enabled thousands of scientists and engineers to develop complex measurement and control applications very quickly and easily.
LabVIEW Student Edition
“The graphical nature of LabVIEW makes it easier to develop working code faster. With LabVIEW, quickly drag and drop built-in functions to simplify acquisition, analysis, control, and data sharing so you can spend less time on syntax errors and more time on creating your application. “
Bitscope – PC Oscilloscopes And Analyzers
BitScopes are USB or Ethernet connected PC Based Mixed Signal Oscilloscopes. This means they capture and display one, two or four analog signals and eight logic or timing signals, simultaneously. Any BitScope can be used as a Digital Storage Oscilloscope, Logic State Analyzer, Spectrum Analyzer or Data Recorder.
USB BitScope 310 – PC Oscilloscope
BS310U is a robust general purpose USB Mixed Signal Scope and Data Acquisition device. BS310U is backward compatible with BS300U which it replaces.
It has 4 times as much capture buffer, a software switchable x10 and x50 analog input multiplier and AC/DC coupling, switchable 50 ohm termination, a double speed built-in USB host interface all in a physical package about 2/3 the size and weight of BS300U.
BS325 is user programmable, software extendable and can be integrated with third party software.
To make this easy the BitScope Library is available for BS325. The library can be used to create custom applications or to integrate one or more BS325 units into specialised testing and data acquisition systems.
The library is included as standard with BS325 and is compatible for Windows, Linux and Macintosh platforms.
This Insulation Testing Reference by AEMC Instruments is a Must Read for all Instrumentation and Electrical Professionals. Even Students and Enthusiasts who want to learn more about Insulation, can find this informative. The other reference articles also are of Learning Interest. Insulation Testing is a Part of Power, Energy, Green, Solar Systems as well. It is an Important part of Product Safety.
Megohmmeters/Insulation – AMEC
Read – Understanding Insulation Resistance Testing
AEMC is an industry leader in current measurement probes, power quality analyzers, ground resistance testers and insulation resistance testers. It was Founded in 1893.
AEMC Instruments – 200 Foxborough Blvd., Foxborough, MA 02035 USA
Seen on the right is the Megohmmeter from AEMC. 6505 is a portable battery/mains powered instrument in a rugged field case.
This Features include automatic calculation and presentation of the Dielectric Absorption Ratio (DAR) and Polarization Index (PI). The Model 6505 displays the test voltage, insulation resistance and the leakage current during the test.
To make an analog design using log amps or multipliers, discovercircuits – four-quad is good for learning. Using a uP for math is better. Look at these links below. Build a Power Meter ! The Metrics for Going Green is with a Energy/Power/Watt meter.