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Current Monitors / Sensors/ Detectors Circuits, Page 1
Sensors / Detectors -- Main Page
Current Monitors / Sensors/ Detectors:  #-B    C    D-Q     R-Z

Last Updated on:
Thursday, April 07, 2016 01:00 PM

Circuits Designed by Dave Johnson, P.E. :

  • AC Current Monitor
    The hobby circuit below shows how a small current transformer from Magnetek can be used to monitor AC current to a load.  The AC voltage developed at the secondary of the transformer can be scaled so it can be read by any digital multimeter.  The transformer is rated at 30 Amps.
  • Bad Light Bulb Indicator
    This request came from a Discover Circuits visitor.  He wanted to turn on a LED indicator light whenever a circuit detected a burned out tail/brake light on a car or truck.  The circuit shown below uses a transistor switch, to detect current flowing through a low value resistor.  If current is flowing to a light bulb, the circuit shunts current around a LED light, keeping the LED turned off. If there is no current detected, the LED turns on.  The circuit should operate from 6v to 24v.... 

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:
A 4- to 20-mA loop needs no external power source -  09/13/01 EDN-Design Ideas....The simple circuit in Figure 1 uses a low-current-drain MAX4073H Amplifier to sense the current flowing through a 4- to 20-mA loop. The circuit senses the current through a 1Ω resistor with a fixed gain of 100 and uses no battery or dc power supply.... [Design Idea by Shyam Tiwari, Sensors Private Ltd, Gwalior, India]
AC Current Indicator Light -  This circuit could be wired into a 120vac power line, which feeds power to any load, ranging from 40 watts to 250 watts.  It will turn on a LED light whenever current is being drawn by a load.  It is especially useful for remote lights, where you may not be able to see if the lamps are receiving power. . [Hobby Corner Circuit by Dave Johnson]
AC Line Current Detector -  This circuit will detect AC line currents of about 250 mA or more without making any electrical connections to the line. Current is detected by passing one of the AC lines through an inductive pickup (L1) made with a 1 inch diameter U-bolt wound with 100% turns of #30, #35 magnet wire. The pickup could be made from other iron type rings or.... [Bill Bowden]

Active-feedback IC serves as current-sensing instrumentation Amplifier -  24-Jul-03 Issue of EDN  High-speed current sensing presents a designer with some significant challenges. Most techniques for sensing current involve measuring the differential voltage the current produces as it flows through a sense element, such as a resistor or a Hall-effect device. The differential voltage across the sense element is generally small and is often riding on a common-mode voltage that is considerably.... [Design Idea by Jonathan Pearson, Analog Devices, Wilmington, MA]
AN-244: A User's Guide to I.C. Instrumentation Amplifiers -  AN-244 Analog Devices Application Notes  (App Note - added 2/06)
AN-245: Instrumentation Amplifiers Solve Unusual Design Problems -  AN-245 Analog Devices Application Notes  (App Note - added 2/06) Traditionally Considered Only for Transducer-Conditioning Applications, Instrumentation Amplifiers Bring Unique Performance Benefits to a Range of Or Applications as Well.
AN-282: Fundamentals of Sampled Data Systems -  AN-282 Analog Devices Application Notes  (App Note - added 2/06)
AN-345: Grounding for Low-and-High-Frequency Circuits -  AN-345 Analog Devices Application Notes  (App Note - added 2/06) Know Your Ground and Signal Paths for Effective Designs. Current Flow Seeks Path of Least Impedance-Not Just Resistance....
AN35 High-Side Current Sensing: Considerations & Applications for High-Side Current Monitoring -  Zetec Semiconductors  Applications Notes  A guide for using  ZXCT range of products. Contained within  note are application ideas for extended supply ranges, a circuit for bi-directional current sensing and an over-current/short circuit protection circuit. Now updated and contained within AN39  (App Note - added 2/06)
AN39 Current Measurement Applications Handbook -  Zetec Semiconductors  Applications NotesThis applications handbook explores how  requirements affect  design for AC and DC current measurement and  implications on cost and performance for different approaches.   (App Note - added 2/06)
AN-539: Errors & Error Budget Analysis in Instrumentation Amplifier Applications -  AN-539 Analog Devices Application Notes  (App Note - added 2/06) Describes a systematic approach to calculating  overall error in an instrumentation Amplifier application.
AN-589: Ways to Optimize the Performance of a Difference Amplifier -  AN-589 Analog Devices Application Notes  (App Note - added 2/06)This Application Note presents several ways to build and optimize  performance of a discrete difference Amplifier. It also recommends Amplifiers that will make  overall solution cost/performance competitive with monolithic instrument Amplifiers.
AN-597: Current Feedback Amplifiers -  National Semiconductor Application Note  (App Note - added 2/06)
AN-671: Reducing RFI Rectification Errors in In-Amp Circuits -  AN-671 Analog Devices Application Notes  (App Note - added 2/06)
AN-683: Strain Gage Measurement using an AC Excitation -  AN-683 Analog Devices Application Notes  (App Note - added 2/06)
AN-772: A Design & Manufacturing Guide for the Lead Frame Chip Scale Package -  AN-772 Analog Devices Application Notes  (App Note - added 2/06)
AN-840: Development of an Extensive SPICE Macromodel for 'Current-Feedback' Amplifiers -  National Semiconductor Application Note....[App Note - ]
Analog-input circuit serves any microcontroller -  20-Dec-01 Issue of EDN  The simple ADC in Figure 1 is perfect for getting analog signals into a purely digital microcontroller. Using just five surface-mount parts, you can assemble it for less than 50 cents (1000], which is approximately half the cost of a single-chip-ADC approach in the same volume. Moreover, this design takes only one pin from the microcontroller to operate.... [Design Idea by Steven Hageman, Agilent Technologies, Santa Rosa, CA]
Bias Voltage & Current Sense Circuits for Avalanche Photodiodes -  AN92 Linear Technology Avalanche photodiodes, used in laser based fiberoptic systems, require high voltage bias and accurate, wide range current monitoring. Bias voltage varies from 15V-90V and current ranges from 100nA to 1mA, a 10,000:1 dynamic range.  This publication presents various 5 volt powered circuits which meet se requirements. Appended sections detail specific circuit techniques and cover measurement practice.
Current Monitors / Sensors/ Detectors:  #-B    C    D-Q     R-Z

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