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Tester or Instrumentation Circuits, Page 5
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Last Updated on: Monday, October 03, 2011 06:07 PM

Circuits Designed by Dave Johnson, P.E. :
  • Electrical Current Indicator
    I designed this circuit as a simple current indicator for any load ranging from 40 watts to 250 watts.  The circuit turns on a small LED, whenever it detects current flowing to a remote load.
  • Expanded Scale 12v Battery Voltage Monitor
    The circuit below expands the battery voltage monitoring scale for a 12v battery so a more accurate voltage reading can be made.  The numbers printed onto the face of a standard 0v to 5v meter are changed so the scale ranges from 10v to 15v.

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

Easy Debugging Terminal -  Build a simple 9600 BAUD 8n1 LCD terminal for debugging and testing the projects having RS232C output....
E-B-C Transistor Pin Identifier -  Tests transistors and diodes for polarity Simple circuitry 9V Battery operation (added 02/05)
E-H 201C Electrometer schematic -  (added 07/07/07)
E-H 215 RL Electrometer schematic -  (added 07/07/07)
EICO 1050 Battery Eliminator schematic  -  (added 07/07/07)
EICO 147a Signal tracer manual w/schematic -  (circuit added 07/07/07)
EICO 232-239 VTVM manual w/schematic -  (circuit added 07/07/07)
EICO 250 AF VTVM schematic  -  (added 07/07/07)
EICO 315 RF/AF Signal generator schematic  -  (added 07/07/07)
EICO 320-322 RF Signal generator manual w/schematic -  (circuit added 07/07/07)
EICO 324 RF Signal generator manual w/schematic -  (circuit added 07/07/07)
EICO 377 AF sine/square wave generator manual w/schematic -  (circuit added 07/07/07)
EICO 379 AF sine/square wave generator manual w/schematic -  (circuit added 07/07/07)
EICO 488 Electronic Switch schematic  -  (added 07/07/07)
EICO 677 tube Tester information, manual w/schematic -  (circuit added 07/07/07)
EICO 680 transistor Tester manual w/schematic -  (added 07/07/07)
EICO 710 grid-dip meter schematic -  (circuit added 07/07/07)
EICO 950B impedance bridge manual w/schematic -  (circuit added 07/07/07)
Elecraft XG2 receiver test oscillator -  (schematic / circuit added 05/07)
Electric field & leakage detector -  (diagram added 05/07)
Electrical Current Indicator -  I designed this circuit as a simple current indicator for any load ranging from 40 watts to 250 watts.  The circuit turns on a small LED, whenever it detects current flowing to a remote load. …. [Designed by David A. Johnson]
Electricity Metering -  Similar considerations can be made for the automatic meter reading where one possible solution consists in using ST7538, ST's Power Line Modem.…(app note added 6/07)
Electrolytic capacitor Tester -  Firstly, we will describe the "add-on" version for the 5x7 Display as this is the cheapest version and, quite frankly, it only deserves a few dollars as a piece of test equipment. It's "all the rage" to have an Electrolytic Tester for servicing equipment and yet I have serviced over 36,000 appliances without one. Possibly it took me a long time to realise electrolytics have the capability of drying out because old-style electros were inherently....(diagram added 05/07)
Electromagnetic Emissions Test Report on Solid State Energy Meter -  Electro Analog Devices Application Notes....[App Note]This report describes electromagnetic immunity testing performed on September 9, 1999 through September 10, 1999 on the Solid State Energy Meter. Testing was performed pursuant to IEC 1036:1996, a standard for alternating static watt-hour meters for active energy.
Electromagnetic Emissions Test Report on the AD7755 -  AD7755 Analog Devices Application Notes....[App Note]This document describes electromagnetic emissions testing performed on the Energy Meter (AD7755)  on September 8, 1999, pursuant to EN55022 requirements. It may be used to demonstrate compliance with the European Union emissions requirements pursuant to the EMC directive
Electromagnetic field detector -  This circuit is sensitive to low frequency electromagnetic radiation and will detect for example hidden wiring or the field that encompasses a transformer. Pickup is by a radial type inductor, used as a probe which responds well to low frequency changing magnetic and electric fields. Ordinary headphones are used to for detection. The field that surrounds a transformer is heard as a50 or 60Hz buzz.   (added 5/02)
Electromagnetic field detector (tomi.geo) -  This lovely circuit is a real gem! Easy to assemble and more sensitive than many commercial devices available. It's based around an LF351 low-noise operational amplifier and a 1mF choke acting as the sensor. Unlike most other simple EMF detectors, this one has a meter output for accurate reading, but alternatively, you can also....(added 10/05)
Electromagnetic Field Probe with Meter Output -  This tester is designed to locate stray electromagnetic (EM) fields. It will easily detect both audio and RF signals up to frequencies of around 100kHz. Note, however that this circuit is NOT a metal detector, but will detect metal wiring if it conducting ac current. Frequency response....(circuit added 05/07)
Electromechanical damping stabilizes analog-meter readings -  29-Sep-05 Issue of EDN  Electronics damps meter-needle swings.... [Design Idea by Alexander Bell, Infosoft International Inc, Rego Park, NY; Edited by Brad Thompson and Fran Granville]
Electronic distance meter Based on Motorola 68HC908QY4 -  (circuit / schematic design added 6/06)
Electronic siren -  An electronic siren made from discrete components.  (schematic added 03/04/05)
Eliminate thermoelectric EMF in low-ohm measurements -  13-Jun-02 Issue of EDN  When two different-metal conductors connect together in a loop and one of the junctions is at a higher temperature than the other, an electrical current flows through the loop. The magnitude of this current depends on the type of metals involved and the temperature differential of the junctions. When you open such a loop, a thermoelectric voltage appears across the open ends.... [Design Idea by John Wynne, Analog Devices, Limerick, Ireland]
EMF Field Probe -  This tester is designed to locate stray electromagnetic (EM) fields. It will easily detect both audio and RF signals up to frequencies of around 100kHz. Note, however that this circuit is NOT a metal detector, but will detect metal wiring if it conducting ac current. Frequency response....(circuit added 05/07)
EMF Probe Version 2 -  An electromagnetic field probe designed to detect changing electric and magnetic fields. The probe has switchable gain, a frequency response up to 400kHz and independent audio and meter monitoring…. [Circuit Design by Andy Collison]
EMF Probe with Meter -  This circuit is sensitive to low frequency electromagnetic radiation and will detect for example hidden wiring or the field that encompasses a transformer. Pickup is by a radial type inductor, used as a probe which responds well to low frequency changing magnetic and electric fields. Ordinary headphones are used to for detection. The field that surrounds a transformer is heard as a50 or 60Hz buzz. (added 6/06) [Andy Collison's circuit]
Emulator Speeds Testing -  09/25/03 EDN-Design Ideas....Designing and testing embedded hardware can be frustrating if you have to rely on somebody else's perhaps-unready firmware to test your hardware. Often, hardware is ready for testing before debugging and system firm-ware are available from software developers. Microprocessor emulators are solutions but.... EDN is migrating links. This link is not verified.  Search the "title" + "EDN" for new link.
Energy Harvesting Using a Current Transformer -  Energy harvesting is all the rage these days.  With some modern electronics, information from low power sensors can be sent to a distant data collection point using a low power RF transmitter.  To power these remote sensors, various energy sources can be tapped into.  Machine vibration, temperature differences, ambient light and stray RF have all been used as low power energy sources.  Sometimes, the sensors are located near AC power cables. Rather than making a direct connection to those cables, an AC current transformer, such as the one shown below, can be used to capture a bit of power.... [Designed by David A. Johnson]
Enhanced battery "gas gauge" keeps its data through glitches -  20-Jan-05 Issue of EDN  Texas Instruments' BQ2010 battery-"gas-gauge" IC offers a convenient method for recording available charge stored in a nickel-cadmium or nickel-metal-hydride battery. However, even though plenty of charge remains available, under certain circumstances, transient-current spikes can fool the BQ2010 into registering a discharged battery.... [Design Idea by Herbert Seidenberg, Costa Mesa, CA]
Envelope Tracker Quells Jitter -  07/07/94 EDN-Design Ideas....Fig 1's envelope tracking circuit solves the problem of receiving ac-coupled NRZ data over a coaxial data link. Because the spectral content of the NRZ data approaches dc (even with alternate frame inversion], the signal tends to integrate in any ac-coupled stage preceding the zero-crossing detector,.... EDN is migrating links. This link is not verified.  Search the "title" + "EDN" for new link.
Environmental Compensation on the AD7142 -  AN-829 Analog Devices Application Notes....[App Note]
E-Power Meter -  Intersil Application Block Diagram....[App Note]
Equivalent Series Resistance meter -  Use this handy device to find all those degraded electrolytic capacitors! [Manfred Mornhinweg]
ERA-SM Test Board: Instructions for Use -  Application Note MiniCircuits.com  (app note added 08/08/08)
ESD Gun Tests IC -  09/12/96 EDN-Design Ideas....You can use the simple ESD-test gun in Figure 1 to test the effects of ESD through sensitive ICs. A piezo-electric type kitchen gas lighter (the so-called ESD gun]is an excellent fast-static-charge generator.  This gun can cause ESD through air and also through conducting and semiconducting materials.... EDN is migrating links. This link is not verified.  Search the "title" + "EDN" for new link.
ESD Sensitivity Testing of Mini-Circuits ERA-4XSM -  AN-60-028  Application Note MiniCircuits.com  (app note added 08/08/08)
ESD Sensitivity Testing of Mini-Circuits ERA-5XSM -  AN-60-029  Application Note MiniCircuits.com  (app note added 08/08/08)
ESR & Low Ohms Meter (Jan '96)  -  I (Bob Barker) originally designed this instrument for my own use, to help identify partly-open-circuit electrolytic capacitors in-circuit, which cause so many faults in switching power supplies, camcorders, TVs, monitors, etc. If you already have one, take a look at the ESR meter hints page, and if you're having problems with a meter you just built, check out the ESR meter problems page.  (circuit added 02/06)
Ethernet 10Base T Simulator Jig yields Zero Emissions -  10/22/98 EDN-Design Ideas....A test jig (Figure 1) is a valuable tool because it evaluates RF emissions from Ethernet unshielded-twisted-pair (UTP] 10BaseT LAN-interface devices without contaminating the measured results with its own RF emissions. When an RF-emissions-measurement lab tests a multiport, UTP 10BaseT Ethernet device....File has multiple circuits, scroll to find this one.... [Design Idea by Glen Chenier, Fujitsu Network Communications, Richardson, TX]
Ethernet Weather Station -  Using an add-on card to the already existing avr ethernet board we build a weather station. That is: A weather station with a build-in webserver. My original plan was to have sensors for temperature, air pressure and wind. I started a prototype and it worked very well except for the wind measurement part. I plan to improve the wind measurement hardware and add it at a later point in time. ….(electronic schematic added 11/08)
Exclusive 2.5 GHz Frequency Counter -  A frequency counter is one of the most important measuring tool we need as homebrew's of RF electronic.  This frequency counter has very high performance and still is very easy to build and to use. Anyone can build it and have a professional frequency measuring tool. The counter is based around a LCD display with 2 lines and 16 chars. I have used a HD44780 based display which is very common. A PIC16F870 circuit controls all counting and display functions. A prescaler is added to make it possible to measure up to 2.5GHz with high sensitivity. The Display Module Size (W x H x T): 80mm X 36mm. The controller PCB has the same size.  This makes the unit very small and slim. …....
Exclusive 2.5 GHz Frequency Counter with Blue 2x16 LCD display -  This project explain a very powerful frequency counter which has many useful software functions. The software can add or subtract 3 different IF frequencies (±455 kHz ,±10.7 MHz and ±21.4 MHz). You have also two level of resolutions, 1kHz and 100Hz....(schematic added 04/05/06)
Expanded Scale 12v Battery Voltage Monitor - The circuit below expands the battery voltage monitoring scale for a 12v battery so a more accurate voltage reading can be made.  The numbers printed onto the face of a standard 0v to 5v meter are changed so the scale ranges from 10v to 15v....[Circuit of the week, designed by David Johnson]
Expanded Scale Battery Volt Meter -  This circuit is used to measure the voltage on a 12V (nominal) lead acid rechargeable battery system. It was specifically designed for use in solar powered systems, but is general enough that it can be used for automotive or other 12V systems. Lead acid batteries normally spend their working lifetime in the voltage range of 11-15 Volts.  This meter circuit was designed to....(added 10/05) [G. Forrest Cook]
Expanded Scale Voltmeter -  I have a 12v batter charger I put together many years ago from bits and pieces found in the junk box. Its been a good little light duty charger, but was lacking any form of battery monitoring, so I decided to give it an upgrade with a expanded scale volt meter and amp meter....(Circuit design added 06/10) 
Expanded Scale Voltmeter uses Just Two Parts -  01/20/94 EDN-Design Ideas....The expanded voltmeter doesn't require trimpots to obtain usable accuracy or require the tedious selection of Zener diodes.  This circuit consists of only two parts and a5V meter. The circuit is completely linear and requires no calibration except the rare mechanical zeroing of the meter. By using.... [Design Idea by DD Cantrell, North Valley Research, Los Molinos, CA]
Expanded-scale indicator revisited -  8-Aug-02 Issue of EDN  The visualization aid that a previous Design Idea describes allows only the expansion of the upper end of the scale (Reference 1]. But what can you do if, according to your project requirements, you need to expand the middle region of the scale? Figure 1a illustrates the challenge. A voltmeter comprises a 100-µA dc meter and a series resistor.... [Design Idea by Abel Raynus, Armatron International Inc, Melrose, MA]
Exploring the Architectures of Network Analyzers -  Aligent Application Note  (app note added 04/05/06)
External Tracking Generator-100kHz...1000MHz -  ....


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