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Questions tagged [constant-current]

Questions regarding Constant Current supplies, devices and applications. As opposed to Constant Voltage supplies. Voltage will vary while Current remains the same. Common in LED lighting applications.

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Constant current load circuit? (20 amp)

I'm pretty new to stack exchange and I've only just gotten my basic circuit analysis classes done in college. For my school's solar racing team, I've been tasked with designing a constant current load ...
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3answers
78 views

Can someone explain this constant current load circuit?

I'm currently a rising junior in EE and I was just wondering if anyone could help explain this circuit for me. The purpose for this is because I need to learn how to build a discharger (constant ...
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2answers
80 views

Why does my Current Regulative Diode not regulate current well?

I recently ordered several E153 CRDs from Semitec (data sheet here) to maintain a steady current to an LED (data sheet here). Mistakenly, I didn't read the "Dynamic Characteristics" portion of the ...
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15 views

Producing Bi-Phasic Constant Current Pulse using L293 IC

I am trying to convert a current source output into the bi-phasic pulses. I thought maybe using L293 IC might help to change polarity of the currents. Here is the picture of design: as can be seen ...
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26 views

Removing Overshoots in constant-current bi-phasic pulse generator

I am designing a constant-current, bi-phasic pulse generator in a simulation study. I have attached the circuit and output current pulse. As it this picture shows, I have a +600 to -600 micro Ampere ...
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1answer
50 views

Can I use a voltage controlled resistor to adjust high side switch current?

A number of high-side switches (e.g. the NCP380) go into constant-current mode when the programmed maximum current is reached. This is typically set with an external resistor according to the required ...
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2answers
122 views

How do I design a constant current load circuit?

I'm currently a rising junior in EE and am honestly completely lost... I've been tasked with designing a constant current load circuit to discharge parts of the battery pack for Georgia Tech's solar ...
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1answer
44 views

Constant Current Output driver connected to 2 COB LEDs - is the hookup valid?

I have a lamp with this hookup. Can someone confirm whether the electrical specs match up such that these can be connected in this way. ld009d-cu03036-m9 - MagTech Constant Current 24-36v output ...
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1answer
39 views

Deciphering which COB LED used in a circuit [closed]

I have two lamps with identical LED circuits. The lamps sometimes blink when turning on. One of the lamps already has a blown COB LED. I suspect the wiring was done wrong. I've opened it up, but I ...
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1answer
105 views

When to use analog PID

So I am building a rather simple constant current load to test power supplies. I am using an INA138 for high-side current measurement with only 5V power (and I have reasons for that, unfortunately) ...
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1answer
58 views

Topology choice for wide-output-voltage-range SMPS

I'm intending on building a off line (230VAC), 50W, isolated, constant-current switch mode power supply. This by itself is not a big challenge with the plethora of application notes and examples ...
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1answer
66 views

Current source with multiple “taps” for driving different LEDs

I'm building a light source for a (one-off, hobby) 8mm film scanner that will be taking several exposures of each frame with different color (R, G, B, and possibly IR) light. I'd started with high-...
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1answer
74 views

How to select the best opamp for a constant current MOSFET driver

I'm trying to create a constant current LED driver. I have found and read information about the miller effect and came up with the schematic below. What are the most important parameters for choosing ...
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0answers
97 views

Solar charger for lithium batteries

I am trying to build a 2s 7.4V solar charged lithium battery pack to power an arduino UNO and SIM900 GSM shield. I have a 12V, 10W solar panel, BMS protection board and a DC-DC CC CV buck converter ...
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1answer
63 views

Variable Constant Current Supply

I've been looking around for a good CCS schematic, and decided to try making a simpler one even if it means it'll behave worse. I need a 12V (would come from an ATX power supply, more than enough ...
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0answers
48 views

Calculate the junction temperature of a MOSFET during pulse

Hi all I have a question regarding using a MOSFET for a constant current source. I have found this question with some answers but it wasn't clear to me yet. I want to create a constant current LED ...
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2answers
73 views

Figuring out the principal working of constant current source

I've the following circuit: simulate this circuit – Schematic created using CircuitLab I was told that this is a constant current source. I think that the resistors \$\text{R}_1\$ and \$\text{...
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2answers
45 views

Adding push button to CC DC to DC converter to adjust CC

I have a CC/CV DC to DC converter I bought on aliexpress. I does not come with a screen so I attached to it an LED voltmeter ammeter. Anyway everything works fine. One thing though, I don't know at ...
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0answers
86 views

Adding Current limit for DIY DC-DC converter (CC/CV battery charging)

I was following the circuitry by great Scott for the DIY buck converter here: https://www.youtube.com/watch?v=m8rK9gU30v4 . Created a converter that gives 0-23V on 24V supply. After this i wanted to ...
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1answer
155 views

Constant current source with shunt fet

I'm want to create a project with a LED strobe with IR LEDs. As LEDs the Osram SFH 4249-UV will be used in strings of 15 LEDs and 32 strings parallel. This results in a Vf of 34.5 - 45 V and a If of ...
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1answer
53 views

Constant Current Regulator position in a series circuit

I'm designing a circuit with 3 LEDs, a CCR (NSI50350), and a power supply in series. My question is: Does it matter where I place the CCR? Can I design my circuit this way: +V--LED1--LED2--CCR--LED3-...
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1answer
138 views

in zener diode current source, to provide constant current, what resistor, etc do I have to use?

I have a load that has varying resistance and want to know the change of resistance by measuring the voltage with constant current. The figure below is known to provide constant current. But I have no ...
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2answers
82 views

Led driver high current and voltage

For a project I have to design a led beacon that will consist of +400 LEDS. These LEDS will be driven only a short amount of time maximum of 3% duty cycle (frequency: 100Hz, pulse: 300us). The LEDS ...
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2answers
596 views

Digital Current limiting with MCU

All current limiting circuits I've found until now use some sort of analog Logic with Op-Amps to limit/control the current. (Why) is no digital current limiting used? I would imagine a shunt resistor ...
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0answers
34 views

SMPS topology for combination of current controlled rail and fixed voltage rail

I'm looking at designing a LED driving power supply that can interface with a universal AC main input (~90VAC-260VAC) and produce 2 rails at the output; one a current controlled rail, and the other a ...
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2answers
330 views

Constant current led dimming

I have a few panel lights which come with normal non-dimmable constant current drivers. I want to add a dimming feature to them, please suggest me a circuit that I can use with Arduino/ESP8266 to ...
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0answers
83 views

Constant Current LED Driver Output Control using PWM

I want to control the brightness of a led which is powered by a constant current driver. On utilizing a MOSFET and pwm signal from an arduino uno the led starts to fade in as the duty cycle ...
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1answer
51 views

Driving 8 x 117W COB LEDs [closed]

I am currently attempting to design a LED grow light using the following LEDs but I am having a very hard time finding a sufficient power supply. 8 x Lumileds - SunPlus CoBs DataSheet 51.7 V, ...
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4answers
117 views

Capacitor bank as a constant current source?

Can a capacitor bank of high power density, be integrated to a circuit such that it acts as a constant current source to a load? Even for a short duration of time.
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4answers
222 views

Constant current source gets heated

I am trying to control some power LEDs using a microcontroller. For this I plan to use a transistor based constant current source to protect the LEDs from getting damaged and PWM on the base of the ...
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2answers
190 views

Why constant current led driver is not used in parallel led strip? [closed]

I know that the constant current led driver is not used in the parallel led strip. and constant voltage led driver is not used in the series led strip. can anyone explain me with the example that why ...
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1answer
88 views

AL8860 LED driver does not output required constant current

The LED driver circuit i've made here does not output a constant 1A current. With an input voltage of 12V and 9V total Vf on the three LEDs (CREE LED star), the current is only 0.65A. Am I ...
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84 views

Calculating value of a current limiting resistor in a constant current circuit?

I am using 12 leds in series with 3.0-3.4 v forward voltage and 400-500mA forward current (these values are from the datasheet). I am using a constant current led driver(24-40v and 580mA). My problem ...
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4answers
140 views

Inductor with constant current source

Hii can anyone explain how to do this. Its Given Answer as 6A. What exactly happens when a constant current source in series with inductor? TIA
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3answers
60 views

Constant Current Load fails to recover after setting load to zero

I'm trying to design a Constant Current load for testing battery cells using the TLC070 Op Amp (what I happen to have on hand) and a low pass filtered (150Ohm + 470uF cap) PWM input from an Ardiuno. ...
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1answer
66 views

Constant current circuit load and without load for voltage measurement?

How can I control the constant current block? What I need? I need to calculate voltage with constant current load (I = 100ma and after some time I need to calculate voltage without load (I = 0), for ...
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2answers
50 views

Zener Shunt Regulator Question

I want an alternative low component, transformerless power supply for low power DC projects, I have used Shunt Regulators in the past but never with AC. Below I have proposed a AC to DC shunt type ...
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0answers
71 views

Designing a constant current pulse circuit

I'm looking for help designing a constant current pulse through a variable load impedance of 10-100k (R4). The ideal response is shown below. This waveform was measured from an off the shelf ...
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1answer
132 views

Analyzing a constant current source

I'm looking at some old chemistry education literature where a constant current source was proposed (J. Chem. Ed. 1969, 46(9) p613, link). I am trying to better understand the circuit and could use ...
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1answer
190 views

Analysis of a modified Howland Current Pump

I am trying to do an analysis of the following modified howland current pump based on the circuit description in the datasheet of the LMP7701. This is a voltage controlled current pump that is driven ...
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1answer
95 views

Laser pointer circuit

I've got a small red laser pointer from a chinese ultrasonic distance meter, which has a small regulator circuit (6mm x 7mm) with SMD components. I guess that is a constant current to drive the laser,...
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1answer
479 views

Constant Current Led Driver (non dimmable) to work with PWM

I have 18W lamps that came with non dimmable led drivers. Ive found datasheet for the main chip (ws3441), which included schematics: and internal block scheme of the chip: I'd like to add dimming ...
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3answers
919 views

Understanding constant current LED drivers (ac to DC)

I am trying to understand the way constant current LED drivers work. Lets say I have a driver with these specs: Description: Power: 18W Output Voltage: DC 36-63V Output Current; 300mA Input ...
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132 views

Laser Diode Driver and Cooling

I am a newbie at analog design, and trying to design a laser diode driving circuit and TEC cooling circuit for a 14 pin laser diode, such as P1550-ADF-B: 1550NM ADF LASER DIODE which has forward ...
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1answer
128 views

Driver selection for high power LEDs

I'm currently working in a project where I need to control the intensity of 24 high power LEDs in 5 levels. I'm planning to use LumiLeds L1CU-BLU1000000000 (https://www.lumileds.com/uploads/705/PB198-...
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2answers
99 views

Voltage doesn't add up in LED circuit

The circuit consists of following: simulate this circuit – Schematic created using CircuitLab And video on this link. Summary: When there is no current flow on the circuit, supply voltage is ...
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2answers
79 views

Over-voltage on a current regulator

Let's say I have a current regulator, or a LED driver, set at 4V that can sink 20mA. If I connect a white LED rated 20mA at 4V to it, then everything is fine. But what happens if I replace, in the ...
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81 views

High power LED array

I’m designing SLA 3D printer and I need to design UV LED array for LCD screen backlight. Preliminary design is 5x3 (5 parallel lines with three LEDs in each). All LEDs will be soldered on PCB. The ...
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1answer
52 views

Help Powering 2x10W LED using a 15v 1A power supply

Beginner here, trying to build a lighting using two 10W SMD LED'S. Please advise me for a better and efficient setup. Here are my specs. Power Supply DC 15v 1A LED specs: Input voltage 9-12v ...
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2answers
88 views

LEDs + Constant Current Driver - Discharging the Circuit

I have a project where I made a series of high power Osram OSLON blue leds using custom boards on aluminium PCB. I just put 16 LEDs in series and joined them to an appropriate constant current supply. ...