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Current Monitors / Sensors/ Detectors Circuits
Sensors / Detectors -- Main Page

Current Monitors / Sensors/ Detectors:  #'s - B      C - G      H - K      L - R     S - Z


Last Updated: November 22, 2021 03:00 PM

Circuits Designed by Dave Johnson, P.E. :
Clip-on AC Current Indicator Circuit -  Several times over the last few years I have received calls from people looking for a simple circuit that would tell them when a sump pump or water well pump motor was running.  These people told me that the electrical circuits that turn on and off . . . Hobby Circuit designed by David Johnson P.E.-November, 2004

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-778-8407

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

Cheap AC Current Measurement -  The easy way to measure high AC currents is to use a clamp meter but these are generally quite expensive and cost several hundred dollars at a minimum.  Add-on clampmeter adaptors can work well but they only work with digital multimeters which have millivolt AC resolution.  This is because the output of most clamp adaptors__ 

Cheap pushbutton replaces rotary switch -  26-Oct-00 EDN Design Ideas:  The problem of setting any one of four modes of aµC-operated process has a straightforward solution  Have the µC check the states of some 4 bits of aµC.    Design by Abel Raynus, Armatron International Inc, Melrose, MA

Circuit Breaker Monitors Leakage Current -  06/21/01 EDN Design Ideas:  The residual-current circuit breaker in Figure 1 continuously monitors the supply lines for any leakage current and immediately disconnects the supply if necessary.  Load-supply wires, both live and neutral, pass through the magnetic core of the CR4311-5 Design by Sharath Kumar, Gemplus R&D Centre, Dubai, United Arab Emirates

Circuit Breaker Provides Overcurrent & Precise Overvoltage Protection -  7-Jun-07 EDN Design Ideas:  A simple circuit breaker delivers precision overvoltage protection and overcurrent protection Design by Anthony H Smith, Scitech, Bedfordshire, England

Circuit Fault Protection with Latching Load Disconnect & Early Warning Indication -  The LT6109 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and two comparators.  Two versions of the LT6109 are available.  The LT6109-1 has the comparators connected in opposing polarity and the LT6109-2 has the comparators connected in the same__ Linear Technology/Analog Devices App Note, Sep 7th 2011

Circuit Fault Protection with Very Fast Latching Load Disconnect -  The LT6108 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and a comparator.  Two versions of the LT6108 are available.  The LT6108-1 has a latching comparator and the LT6108-2 has a non-latching comparator.  in addition, the current sense amplifier__ Linear Technology/Analog Devices App Note, Sep 7th 2011

Circuit Measures Capacitance or Inductance -  10/21/10 EDN Design Ideas:  Use instruments you already have and a few equations when you don’t have a capacitance meter.   Design by Jim McLucas, Broomfield, CO

Circuit provides high-side current sensing -  10/12/00 EDN Design Ideas:   in power supplies or battery chargers, you often need information about the current flowing in the high-side rail.  Figure 1 shows a common circuit for obtaining this information.  The circuit provide as a ground-referenced voltage proportional to the current flowing through the high-side sense resistor, RS.  The circuit needs an additional high-side supply, VP.  Design by M Ossmann and B Kazay Aachen University of Applied Sciences, Germany

Circuit senses high-side current -  03/01/01 EDN Design Ideas:  The accurate, high-side, current-sense circuit does not use a dedicated, isolated supply voltage, as some other schemes do.    Design by Bobell

Classic High-Precision Low Side Current Sense -  This configuration is basically a standard non-inverting amplifier.  The op amp used must support common-mode operation at the lower rail and the use of a Zero-Drift type (as shown) provides excellent precision.  The output of this circuit is referenced to the lower Kelvin contact, which could be ground in a single-supply application.  __ Linear Technology/Analog Devices App Note, Mar 31, 2010

Clip-on AC Current Indicator Circuit -  Several times over the last few years I have received calls from people looking for a simple circuit that would tell them when a sump pump or water well pump motor was running.  These people told me that the electrical circuits that turn on and off . . . Hobby Circuit designed by David Johnson P.E.-November, 2004

Current Sense Auto Power Switch -  A current sensing switch turns on multiple devices from one master __ Designed by Rod Elliott  ESP

Current Sense Curcuit Collection -  AN105 Sensing and/or controlling current flow is a fundamental requirement in many electronics systems, and the techniques to do so are as diverse as the applications themselves.  This App Note compiles solutions to current sensing problems and organizes the solutions by general application type.  These circuits have been culled from a variety of documents.  __ Linear Technology/Analog Devices

Current Sensor -  High-wattage appliances like electric irons, ovens and heaters result in unnecessary power loss if left 'on' for hours unnoticed.  Here is a circuit that senses the flow of current through the...__ Electronics Projects for You

Current sensor measures 0 to 500A -  09/30/99 EDN Design Ideas:  The simple circuit in Figure 1a can sense both low and high current levels without low sensitivities or loss of accuracy either at the low or the high end of the scale.  The circuit is useful for discerning either low or high currents in noisy environments.  The circuit comprises a current mirror formed by complementary pair Q1 and Q2 and the feedback provided by Q3.  When a current I flows through RS, the voltage at the emitter of Q2 increases.  The voltage at the base of Q3 then increases, which increases the current, iEQ3, through Q3's emitter.   Design by Jose Carrasco, Universidad de Valencia, Department Electronica, Valencia, Spain

Current-sense Amplifier handles high voltages -  11/06/97 EDN Design Ideas:  High-side current-sense amplifiers, such as IC 1 in Figure 1, monitor current from a battery or dc power line in systems for which the ground-return continuity is crucial.  IC 1's 36V maximum operating voltage, however, excludes some applications, including traction-motor batteries and central-exchange power supplies, both of which require operation at voltages exceeding 72V.  The external circuitry in Figure 1 allows IC 1 to monitor current at voltages of 300V and greater.  Q1 and Q2 form a current source whose compliance voltage provide as the high-voltage capability.  IC 1 draws its 100-µA supply current from a simple floating power supply comprising C1, C2, avalanche diode D1, and the Q1-Q2 current source.    Design by Andy Fewster, Maxim Integrated Products, Reading, UK

Current-sense Amplifier precisely measures Low side -  09/16/99  EDN Design Ideas:  Several integrated high-side current-sense amplifiers, such as the MAX4172 (Maxim integrated Products, www.maxim-ic.com) , make it easy to measure the current from a positive power supply.  With a couple of resistors, these devices provide a ground-referenced voltage output that is proportional to the delivered current (Figure 1a).   Design by John Ursoleo

Current-sense IC Prevents OverCurrent Damage -  04/25/96 EDN Design Ideas:  CMOS -interface ICs  serve as gateways to the wired connections in electronic systems.  Mishandling those external connections can damage the interface ICs  by causing shorts to ground or by applying voltages that result in latch-up.   Design by Gary Sellani, Maxim Integrated Products, Sunnyvale, CA

Current-Sense Monitor & MOSFET Boost Output Current -  28-May-09 EDN Design Ideas:  You can bypass BDC current-settings resistors and use a MOSFET to increase current Design by Gyula Diószegi and János Nagy, Divelex Ltd, Budapest, Hungary

Current-sensing scheme improves PFC on/off sequences -  06/27/02 EDN Design Ideas:  PFC (power-factor-correction] preconverters typically use the step-up, or boost, configuration, because this type of converter is relatively easy to implement (Figure 1).  However, this topology requires the output voltage to be higher than the input voltage.  When this condition is not the case—for example, with on/off sequences or under load conditions—some inrush current flows thro Design by Joël Turchi, On Semiconductor, Toulouse, France

Dual transistor improves current-sense -  08/16/07  EDN Design Ideas:  A two-transistor circuit eliminates variation in output due to temperature Design by Robert Zawislak, PE, Consultant, Palatine, IL

Dual-Coil Relay Driver Uses Only Two MOSFETs -  22-Oct-09 EDN Design Ideas:  Differentially drive relays to minimize power consumption Design by Mehmet Efe Ozbek, PhD, Atilim University, Ankara, Turkey

Dynamo Current & Voltage Regulator -  Useful for lovers of older cars, motorcycles and boats. __ Designed by Manfred Mornhinweg

Eight Decade Current Sensing Log Amplifier -  The low pA's of bias current of CMOS amplifiers make them suitable for high input impedance current sensing applications.  By taking advantage of the logarithmic relationship of a transistor base-emitter voltage to it's collector current a very wide range of measured input current can be converted to a voltage.  in this circuit the input current can span six decades from 10nA to 10mA.  The positive tempco resistor compensates for the 0.3%/C tempco of the logging transistors scale factor coefficient (kT/q) __ Linear Technology/Analog Devices App Note, Mar 16, 2010

Electronic Breaker -  This circuit uses the on-resistance of the MOSFET as the current sensor.  Reset it by removing the input power or the load.  The circuit draws no current unless tripped.   __ Designed by Andrew R. Morris

Energy-Tripped Breaker Trips After a Time Interval that Varies as a Function of Sensed Load Current -  The circuit of this circuit has three distinct parts – circuit breaking, current sensing and timing.  The circuit breaking function can be any type of electronically controlled relay or solid state switch, properly sized for voltage and current ratings of the load being protected.  Load current sensing is achieved via __ Linear Technology/Analog Devices App Note, Sep 7th 2011

Full-Bridge Load Current Monitor -  The LT1990 is a micropower precision difference amplifier with a very high common mode input voltage range.  it has pin selectable gains of 1 or 10.  The LT1990 operates over a ±250V common mode voltage range on a ±15V supply.  The inputs are fault protected from common mode voltage transients up to ±350V and differential voltages __ Linear Technology/Analog Devices App Note, Apr 5th 2010

Fully Isolated AC Power & Current Monitor -  This circuit highlights the use of the LT2940 in power and current monitoring in an isolated AC application.  The LT2940 excels in this type of applications since it can monitor where both the current and the voltage may be variable due to supply voltage uncertainty, component parametric changes, transient conditions, time-varying__ Linear Technology/Analog Devices App Note, Apr 26th 2010

Current Monitors / Sensors/ Detectors:  #'s - B      C - G      H - K      L - R     S - Z

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