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4–20ma Current Loop Tester - This circuit injects an adjustable current
through a wire loop. Using a digital current meter, the current can be
adjusted from near zero to over 24 milliamps. (added 12/04) …. [Designed by
David A. Johnson] |
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60-mA current-source feeds telecomm lines - 12/18/97 EDN-Design Ideas An
isolated 60-mA current source provides 120V of compliance for use in
telecommunication interfaces (Figure 1). Constant-current line feed provides dc
power for downstream circuitry independent of line length and provides inherent
short-circuit protection. The key to isolated..... [Design Idea 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. (added 12/04) …. [Designed by David A.
Johnson] |
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A Simple Current-Sense Technique Eliminating a Sense Resistor AN-7 -
Application Note 7 from Microsem.....[App Note] |
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Amplifier and current-source emulate instrumentation amplifier -
13-Nov-03 Issue of EDN 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 with high-series-output impedance and
thus requires an appropriate high-input-impedance amplifier..... [Design Idea by
Dobromir Dobrev, Jet Electronics, Sofia, Bulgaria] |
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AN-1244: Photo-Diode Current-To-Voltage Converters - National
Semiconductor Application Note (app note added 2/06) |
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AN-240: Wide-Range Current-To-Frequency Converters - National
Semiconductor Application Note (app note added 2/06) |
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AN-D16: Lnd1 Series: Constant Current Sources And - Supertex
Semiconductors (app note added 2/06) |
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AN-D18: Dn25 Series: Constant Current Sources And - Supertex
Semiconductors (app note added 2/06) |
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Basic Current Source - Circuit Ideas for Designers Application Notes
Advanced Linear Devices, Inc.....[App Note] |
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Bipolar current-source maintains high output impedance at high frequencies -
5-Dec-05 Issue of EDN Use line-receiver/amp ICs to build high-frequency
constant-current sources..... [Design Idea by Alex Birkett, University College
London, Hospital National Health Service, London, UK; Edited by Brad Thompson and
Fran Granville] |
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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-mode.....PDF contains multiple
circuits, scroll to find this circuit…. [Design Idea by Christophe Basso, ON
Semiconductor, Toulouse Cedex, France] |
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Bipolars Provide Stable Current-source - 09-24-98 Issue of EDN
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.....File contains several circuits, scroll to this one..... [Design Idea
by Bill Morong, Morong's Harness, Dover-Foxcroft, ME] |
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Buffered Current Source - Circuit Ideas for Designers Application Notes
Advanced Linear Devices, Inc.....[App Note] |
| Build a precise DC floating-current-source -
18-Aug-05 Issue of EDN Use a general impedance converter and resistors to
develop a specialized current source..... [Design Idea by D Ramírez, S Casans, C
Reig, AE Navarro, and J Sánchez, University of Valencia, Burjassot, Spain; Edited
by Brad Thompson and Fran Granville] |
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Cascode Current Source - Circuit Ideas for Designers Application Notes
Advanced Linear Devices, Inc.....[App Note] |
|
Circuit forms novel floating current-source - 1-May-03 Issue of EDN
Figure 1 shows a polarization circuit applicable to ISFET (ion-sensitive
field-effect-transistor] sensors. ISFETs are solid-state chemical sensors that
measure the pH value of a solution in biomedical and environmental applications,
for example. The circuit in Figure 1 is extremely simple; it sets fixed-bias
conditions for ISFET sensors (VDS=I0 RX; IDS=I0]..... [Design Idea by S Casans, AE
Navarro, and D Ramirez, University of Valencia, Burjassot, Spain] |
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Circuit provides constant-current for ISFETs/MEMFETs - 26-Oct-00 Issue
of EDN-Design Ideas.....ISFETs and MEMFETs (ion-sensitive and membrane FETs] are
solid-state chemical sensors that provide an electrical signal associated with the
change of a….[Pdf contains several circuits, scroll to find this one…. [Design
Idea by S Casans, D Ramirez, and AE Navarro, University of Valencia, Burjassot,
Spain] |
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CMOS Buffer Delivers Precise Current Pulses - 12/08/94 EDN-Design
Ideas.....The circuit in Fig 1 delivers stable, fast-settling reference-current
pulses. You can use the circuit in systems employing A/D, D/A, or V/F converters.
Digital input pulses, VP, connect to IC3B, a 74AC240 buffer. The 5.00V reference,
IC1, constrains IC3B's output, VR, to either VREF or0V. IC3B's rise and fall times
are <3 nsec..... EDN is migrating links. This link is not verified. Search
the "title" EDN for new link. |
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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 but any voltage from 9v to 12v will work.....
[Designed by David A. Johnson] |
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Constant Current Amplifier - (electronic diagram added 6/03)
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Constant Current Battery Charger - A simple method of charging a battery
from a higher voltage battery is shown in the circuit below to the left. Only one
resistor is needed to set the desired charging current and is calculated by
dividing the difference in battery voltages by the charge current. So, for example
if 4 high capacity (4000 mA hour) ni-cads are to be charged at 300 mA from a 12
volt battery, the resistor need,..... [Bill Bowden's website] |
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Constant Current Charger - This simple constant current source uses an
LM317 regulator IC. N.B. The pin-outs of the IC are not a mistake, the output is
taken from the adjustment pin. I found this circuit to charge all my NiCad
batteries, and I use a Kambrook mechanical light-timer (or equiv.) for 110vac to
time the charge..... [John Nooyen's electronic schematic] |
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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. (added 12/04) …. [Designed by David A. Johnson] |
Constant Current LED
Driver 5
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 way to do this is shown below. This works fairly
well but it has two weaknesses. It requires a 0.6v voltage drop across the
current shunt resistor and due to the base-emitter voltage temperature
sensitivity, the current increases with temperature.....[Designed
by David A. Johnson] |
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Constant current, constant voltage converter drives white LEDs -
2-Sep-04 Issue of EDN LEDs usually take their drive from a constant
dc-current source to maintain constant luminescence. Most dc/dc converters,
however, deliver a constant voltage by comparing a feedback voltage to an internal
reference via an internal error amplifier. The easiest way to turn a simple dc/dc
converter into a constant-current source is to use a sense resistor to convert the
output current to a voltage..... [Design Idea by Keith Szolusha, Linear Technology
Corp, Milpitas, CA] |
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Current Regulators - I have been asked a couple times about constant
current regulators. Here are a couple simple ones. Set R2 on both circuits for 0.6
volts at the desired current. Select Q1 and select R1 according to the amount of
current you would like to source or limit. (circuit added 9/07) |
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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 added
02/09) |
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Current Source Mirror - Circuit Ideas for Designers Application Notes
Advanced Linear Devices, Inc.....[App Note] |
|
Current Source Multiplication - Circuit Ideas for Designers Application
Notes Advanced Linear Devices, Inc.....[App Note] |
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Current Source with Gate Control - Circuit Ideas for Designers
Application Notes Advanced Linear Devices, Inc.....[App Note] |
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Current-source & Sink Circuits Have Low Tc - 07/04/96 EDN-Design
Ideas..... EDN is migrating links. This link is not verified. Search the
"title" EDN for new link. |
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Current-source Allows Measuring Three Wire Rtd - 07/06/00 EDN-Design
Ideas..... EDN is migrating links. This link is not verified. Search the
"title" EDN for new link. |
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Current-source enables op amp's output to go to ground - 5-Aug-04 Issue
of EDN The LM324 is a cost-effective choice for an op amp, especially when
you need to apply ground-level inputs. Although its output purportedly includes
ground, its poor current-sinking capability limits the applications. At output
voltages lower than 0.5V, the op amp's sinking current ranges only from 2 to 100
µA..... [Design Idea by Frank Chan, Vancouver, BC, Canada] |
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Current-source Forms Unusually Simple 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.… EDN is migrating links. This
link is not verified. Google the "title" EDN for new link. |
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Current-source has high compliance - 09/01/00 EDN-Design Ideas EDN
is migrating links. This link is not verified. Search the "title" + "EDN"
for new link. |
|
Current-source has High-Output Impedance - 06/22/00 EDN-Design Ideas EDN
is migrating links. This link is not verified. Search the "title" + "EDN"
for new link. |
|
Current-source is Nonvolatile - 05/07/02 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 RFand
laser-communications drivers. The circuit in Figure 1, for example, is
particularly suited for setting the drive current for the optical pump in widely
tunable VCSELs (vertical-cavity..... EDN is migrating links. This link is not
verified. Google the "title" EDN for new link. |
|
Current-source makes novel Class A buffer - 3-Apr-08 Issue of EDN
A pair of classic current sources in totem-pole configuration enables a novel
Class A buffer..... [Design Idea by Horst Koelzow, Winnipeg, MB, Canada] |
