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Current Source / Current Sink Circuits

Current Source Circuits:  #'s - B       C - G       H - S      T - Z
 

Last Updated: December 31, 2017 06:47 AM

Circuits Designed by Dave Johnson, P.E.

1 Amp Current InjectorI designed and built this thing many years ago.  I published the hobby circuit in the now defunct “Radio Elecronics” magazine back in 1992.  The electronic circuit injects a precise 1 amp of current into any unknown resistor, up to about two ohms.  Two alkaline C cells power the complete circuit.. . . Circuit by Dave Johnson P.E.-July, 2006

100ma Current SourceOften in industrial control systems a constant current source is needed, which is controlled by a computer and referenced to circuit ground.  The circuit below converts a zero to 5v signal from a computer’s analog output into a current, with a full scale of 100ma.  The circuit shown requires a 9v DC supply. . . Circuit by David Johnson P.E.-July, 2008

6v NMH/NiCd Battery TesterI designed this circuit to test rechargeable six volt battery packs under constant current conditions.  As designed, the circuit applies a 10 amp load to the battery pack.  A heat sink must be used on the main power transistor. . . Circuit by Dave Johnson P.E.-December, 2004




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

±5A, 2.5V (2-Quadrant) μModule Voltage Regulator -  The LTM8052 is a 36VIN, 5A, 2-quadrant constant-voltage, constant-current   (CVCC) step-down μModule® regulator.  Included in the package are the switching controller, power switches, inductor and support components.  Operating over an input voltage range of 6V to 36V, the LTM8052 supports an output voltage range of 1.2V to 24V.  __ Linear Technology/Analog Devices App Note, Mar 30th 2012

0A to 2A Current Source -  The LT1995 amplifies the sense resistor drop by 5V/V and subtracts that from VIN, providing an error signal to an LT1880 integrator.  The integrated error drives the PMOSFET as required to deliver the commanded current.  __ Linear Technology/Analog Devices App Note,

1 Amp Current Injector -  I designed and built this thing many years ago.  I published the hobby circuit in the now defunct “Radio Elecronics” magazine back in 1992.  The electronic circuit injects a precise 1 amp of current into any unknown resistor, up to about two ohms.  Two alkaline C cells power the complete circuit.. . . Circuit by Dave Johnson P.E.-July, 2006

100ma Current Source -  Often in industrial control systems a constant current source is needed, which is controlled by a computer and referenced to circuit ground.  The circuit below converts a zero to 5v signal from a computer’s analog output into a current, with a full scale of 100ma.  The circuit shown requires a 9v DC supply. . . Circuit by David Johnson P.E.-July, 2008

1-Hz to 100-MHz VFC features 160-dB dynamic range -  09/01/05 EDN-Design Ideas Transform voltage to current over wide frequency, amplitude__ Circuit Design by Jim Williams, Linear Technology Corp

2-Terminal 3A Current Source -  The LT3083 is a 3A low dropout linear regulator that can be paralleled to increase output current or spread heat on surface mounted boards.  Architected as a precision current source and voltage follower, this new regulator finds use in many applications requiring high current, adjustability to zero, and no heat sink.  The device __ Linear Technology/Analog Devices App Note, Mar 9th 2011

2-Terminal Temperature-to-Current Thermometer Suitable for Use at the End of Long Wire Runs -  By adding the LT3092 to a thermistor kit along with three 0.1% accuracy resistors and one final trim, a very accurate 2-terminal temperature-to-current converter can be built.  This circuit measures 700μA operating current at 0°C, dropping by 2μA every degree until 100°C, at which point the current measures 500μA.  The obvious __ Linear Technology/Analog Devices App Note, Oct 26th 2010

3-transistor current source covers wide range -  05/31/14  EDN-Design Ideas This Design Idea is a two-wire current regulator that strikes a good balance between performance and parts count.  Employing three transistors, three resistors, and one LED, it achieves good regulation   (better than 1% over most of the voltage range), lower operating voltage   (1.2V typical), and better tempco   (0.07%/K) than other circuits of similar complexity.  It is designed to operate in a range of currents from tens of milliamperes to several amps.  It does not use any hard to find parts; for example: an LM10 can be used to make an even higher performance circuit, but this IC is not multi-sourced and is likely to be discontinued.  __ Circuit Design by Einar Abell0

40 Volt Current-source Operates from  40 to +85°C -  06/22/95 EDN-Design Ideas Wide-output-current-range sources that accommodate a wide supply and temperature range require special consideration.  basic circuit of   (Fig 1]provIdeas IOUT = VREF/RS; typically, VREF is 1.25V for__ Circuit Design by Ray Scott, SOR Inc, Lenexa, KS

60-mA Current Source Feeds Telecomm Lines -  12/18/97 EDN-Design Ideas An isolated 60-mA current source provIdeas 120V of compliance for use in telecommunication interfaces  (Figure 1).  Constant-current line feed provIdeas dc power for downstream circuitry independent of line length and provIdeas inherent short-circuit protection.  The key to isolated__ Circuit Design by Kurk Mathews, Linear Technology Corp, Milpitas, CA

6v NMH/NiCd Battery Tester -  I designed this circuit to test rechargeable six volt battery packs under constant current conditions.  As designed, the circuit applies a 10 amp load to the battery pack.  A heat sink must be used on the main power transistor. . . Circuit by Dave Johnson P.E.-December, 2004

A Compendium of Pleasant Current Events -  Linear Technology AN90 __ Designed by Jim WilliamsApr 1st, 2002

Achieve Constant Current Over Wide Range of Terminal Voltages -  11/04/10 EDN-Design Ideas Eliminate errors caused by bias currents and temperature drifts.  __ Circuit Design by Donald Boughton, Jr, International Rectifier, Orlando, FL

Adjustable Two Terminal 200mA Current Source -  The LT3092 requires only two resistors to set the current between 0.5mA and 200mA __ Linear Technology/Analog Devices App Note, Mar 24th 2010

Amplifier & Current Source Emulate Instrumentation Amplifier -  11/13/03  EDN-Design Ideas The classic three- or two-op-amp instrumentation-amplifier circuits are standard ways to amplify a small-amplitude differential signal contaminated with high common-mode noise.  In some applications, the signal source is floating wi__ Circuit Design by Dobromir Dobrev, Jet Electronics, Sofia, Bulgaria

AN90Current Sources for Fiber Optic Lasers: A Compendium of Pleasant Current Events -  Linear Technology AN90 __ Designed by Jim WilliamsApr 1st, 2002

AN92Bias Voltage and Current Sense Circuits for Avalanche Photodiodes -  Linear Technology AN92 __ Designed by Jim WilliamsNov 1st, 2002

Basic Current Source  -  Circuit Ideas for Designers App Note___ Advanced Linear Devices, Inc

Bias Voltage and Current Sense Circuits for Avalanche Photodiodes -  Linear Technology AN92 __ Designed by Jim WilliamsNov 1st, 2002

Bidirectional Current Source -  The LT1990 is a differential amplifier with integrated precision resistors.  The circuit shown is the classic Howland current source, implemented by simply adding a sense resistor.  __ Linear Technology/Analog Devices App Note, Mar 31, 2010

Bipolar current source maintains high output impedance at high frequencies -  12/05/05 EDN-Design Ideas Use line-receiver/amp ICs to build high-frequency constant-current sources__ Circuit Design by Alex Birkett, University College London, Hospital National Health Service, London, UK

Bipolars provide safe latch-off against opto failures -  12/07/00 EDN-Design Ideas A typical SMPS  (switch-mode power supply]uses a reference voltage and an optocoupler to regulate the output voltage.  The optocoupler carries the isolated information from the secondary side to the primary nonisolated side and ensures proper output regulation.  Current-modePDF contains multiple circuits, scroll to find this circuit.   __ Circuit Design by Christophe Basso, ON Semiconductor, Toulouse Cedex, France

Bipolars provide stable current source -  09/24/98 EDN-Design Ideas NOTE :  multiple circuits, scoll to this one.  It's possible to implement a precise current source with a useful output at high frequencies, without using operational amplifiers.  The circuit in Figure 1a suffers inaccuracies from both the VBE drop and the finite base current of the transistor.  The circuit in Figure 1b overcomes the base-current problem, but has two VBE drops and does not perform well at high frequencies.   __ Circuit Design by Bill Morong, Morong's Harness, Dover-Foxcroft, ME

Buffered Current Source -  Circuit Ideas for Designers App Note___ Advanced Linear Devices, Inc

Build a precise DC floating-current source -  08/18/05 EDN-Design Ideas Use a general impedance converter and resistors to develop a specialized current source__ Circuit Design by D Ramírez, S Casans, C Reig, AE Navarro, and J Sánchez, University of Valencia, Burjassot, Spain


Current Source Circuits:  #'s - B       C - G       H - S      T - Z


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