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Converters:  Voltage to Current
Converters -- Main Page

Voltage to Current Circuits:  #'s - F     G - Z
 

Last Updated: December 31, 2017 06:47 AM

Circuits Designed by Dave Johnson, P.E.

 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 David 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

 Computer Controlled 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 A. Johnson P.E.-July, 2008

 Constant Current Drives LEDsLEDs are current driven devices.  The light they produce is proportional to the current flowing though them.  One way to maintain a fairly steady light output is to keep the current through the LED fixed, even as the supply voltage may change.  A classic . . . Hobby Circuit designed by David A. Johnson P.E.-December, 2010

 Constant Current LED DriverBob Pease from National Semiconductor came up with this circuit and I have used it many times.  It maintains a constant current through one or more LEDs.  A single resistor controls the desired current. . . . Hobby Circuit designed by David A. Johnson P.E.-November, 2004

 Current InjectorWhen you need to measure resistance down to a few micro ohms, this circuit works great.  It is powered from two "C" cell batteries and is designed to inject a well regulated one amp of current into the unknown resistance.  By measuring the voltage drop across the resistor with a digital voltmeter, the resistance value can be accurately measured.  The circuit also is equipped with a low battery monitor.  Published in Popular Electronics, November 1992modified on July 11, 2006. . . Circuit by David Johnson P.E.-June, 2000

 Current Source is Computer ControlledOften 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 . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2008


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 David Johnson P.E.-July, 2006

1 Hz to 10 MHz Voltage to Frequency Converter -  Schematic only __ Designed by va3iul

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. __ 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

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

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

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

Build a Direct Current Converter -  To have a Direct Current Converter on your work bench increases greatly your capability of experimenting within an ample range of electronic components that need over 100 volts to be driven.  Among these components we find neon lamps, nixie display numerical tubes, and some kind of triode and pentode valves.  Neon lamps open a broad field to build audio oscillators, blinkers and flashers, polarity finders, display decorations, hot chassis checkers __ Designed by braincambre500 @ yahoo.com

Computer Controlled 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 A. Johnson P.E.-July, 2008

Constant Current Drives LEDs -  LEDs are current driven devices.  The light they produce is proportional to the current flowing though them.  One way to maintain a fairly steady light output is to keep the current through the LED fixed, even as the supply voltage may change.  A classic . . . Hobby Circuit designed by David A. Johnson P.E.-December, 2010

Constant Current LED Driver -  Bob Pease from National Semiconductor came up with this circuit and I have used it many times.  It maintains a constant current through one or more LEDs.  A single resistor controls the desired current. . . . Hobby Circuit designed by David A. Johnson P.E.-November, 2004

Current Injector -  When you need to measure resistance down to a few micro ohms, this circuit works great.  It is powered from two "C" cell batteries and is designed to inject a well regulated one amp of current into the unknown resistance.  By measuring the voltage drop across the resistor with a digital voltmeter, the resistance value can be accurately measured.  The circuit also is equipped with a low battery monitor.  Published in Popular Electronics, November 1992modified on July 11, 2006. . . Circuit by David Johnson P.E.-June, 2000

Current Source -  Getting optimum performance in certain applications requires that some components, sensors, DC motors, transistors, be driven or biased by a constant current.  We're mostly familiar with voltage regulators and their ability to maintain a constant voltage under varying current conditions.  In this application, your challenge is to provide a constant  (spice design) 

Current source allows measuring three-wire RTD -  07/06/00 EDN-Design Ideas In applications in which you need remote measurement of temperature with a three-wire RTD  (resistance-temperature detector) , it is important to eliminate the ohmic errors caused by the excitation current flowing through the wiring resistance.  You can locate the RTD more than 1000 ft from the ADC with wiring resistance in the tens of ohms.    __ Circuit Design by John Wynne, Analog Devices, Limerick, Ireland

Current source forms unusually Simple Circuit regulator -  09/12/97 EDN-Design Ideas Simple regulator uses a switching current source to drive a pair of shunt Zener regulators, circuit produces ±15V dual outputs, for total output power of approximately400 mW form100-400-Volt DC source __ Circuit Design by Kennan Herrick, ESI Electronics, San Francisco, CA

Current source has high compliance -  09/01/00 EDN-Design Ideas Current sources are useful in many areas of electronics, such as voltage and current division, current transmitters, excitation of thermistors, RTDs, bridges, potentiometers, and circuit biasing.  Current sources are either fixed- or adjustable-current types.  For the dual-op-amp current source in Figure 1 , the load current, I L , is adjustable by varying V IN  (0 to±1.   __ Circuit Design by Frank Vitaljic, Bellingham, WA

Current source has high output impedance -  06/22/00  EDN-Design Ideas A reference current source needs high accuracy, low temperature drift, and high output impedance.  Available IC current sources come with some of these features.  However, at current levels greater than 1 mA, their output impedance decreases to less than 10 MW.  Figure 1 shows a composite 10-mA current-source configuration that has a compliance voltage of 5 to 42V, a set-current error of less than 1%, a temperature drift of less than 45 ppm/°C, and an output impedance of greater than 100 MW.   __ Circuit Design by Clayton B Grantham, National Semiconductor, Tucson, AZ

Current Source is Computer Controlled -  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 . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2008

Current Source Makes Novel Class a Buffer -  3-Apr-08 EDN-Design Ideas A pair of classic current sources in totem-pole configuration enables a novel Class A buffer __ Circuit Design by Horst Koelzow, Winnipeg, MB, Canada

Current Source Mirror -  Circuit Ideas for Designers App Note__ Advanced Linear Devices, Inc

Current Source Multiplication -  Circuit Ideas for Designers App Note__ Advanced Linear Devices, Inc

Current Source with Gate Control -  Circuit Ideas for Designers App Note__ Advanced Linear Devices, Inc

Current sources & mirrors -  There are many useful circuit elements: current sources and current mirrors are two of them.  Sources and mirrors are so closely related that it is sometimes difficult to differentiate between them.  So what?labelling things is a function of language not of electronics!  __ Designed by Richard Torrens

Current Sources for Fiber Optic Lasers -  AN90 A large group of fiber optic lasers are powered by DC current.  Laser drive is supplied by a current source with modulation added to the signal.  The current source, although conceptually simple, constitutes an extraordinarily tricky design problem.  There are a number of practical requirements for a fiber optic current source and failure to consider them can cause laser and/or optical component destruction.  This App Note describes ten laser current source circuits with a range of capabilities.  High and low current types are presented, along with designs__ Linear Technology/Analog Devices

Current sources for fiber-optic lasers: a compendium of pleasant current events -  08/22/02  EDN Technical Article: It takes an aura of thoughtful caution to design a laser current source.  A range of circuits that use linear and switched-mode techniques shows how.   __ Circuit Design by Jim Williams, EDN's most revered contributor, passed away in June 2011 after a stroke.  He was 63.

Current-source is nonvolatile -  02/07/02  EDN-Design Ideas Digitally programmable current sources that feature automatic trimming and retain the setting despite power-down cycles are useful in applications such as RF- and laser-communications drivers.  The circuit in Figure 1, for example, i __ Circuit Design by Stephen Woodward, University of North Carolina, Chapel Hill

DAC Controlled 100mA Current Source -  The LT3092 easily interfaces with an external DAC to allow digital current control.  __ Linear Technology/Analog Devices App Note, Mar 24th 2010

DC Voltage & Current Source -  A reference volatge and current source for testing data converter and analog amplifier.  A simple circuit built with TI LinCMOS opamp, TLC254C provides multiple outputs: +2.5V, 0 to +2.5V and 0 to 250uA.  The circuit is operated with 9V battery. __ Designed by Wichit Sirichote

Design Formulas Simplify Classic V/I Converter -  01/20/00 EDN-Design Ideas Figure 1 shows a classic voltage-to-current  (V/I) converter.  You can select the resistor values such that the output current in the load, R L , varies only with the input voltage, V IN , and is independent of R L .  The circuit is widely used in industrial instruments for supplying a 4- to 20-mA signal.   __ Circuit Design by Dudley Nye

Digital current-source is nonvolatile -  02/07/02  EDN-Design Ideas Digitally programmable current sources that feature automatic trimming and retain the setting despite power-down cycles are useful in applications such as RF- and laser-communications drivers.  The circuit in Figure 1, for example, i __ Circuit Design by Stephen Woodward, University of North Carolina, Chapel Hill


 Voltage to Current Converter Circuits:  #'s - F     G - Z


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