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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95 views

How to calculate the tolerance of this constant current circuit?

I am using the circuit below to provide constant current to th LEDs. I request your suggestion on how to calculate the tolerance of current (minimum and maximum variation of set current) due to ...
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39 views

Current Sink with OP184

I got a question. I'm building a current sink for a project and below you can see what i came up with. I modified the Linear Tech. circuit (LT1492) because i wanted to have lower Vos. I also added 3 ...
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92 views

Powering LEDs, dim LED in parallel

I want to build an light fixture for my aquarium and decided to use LEDs, almost everywhere it's suggested to wire the LEDs in series. but that will need a high voltage for many high power LEDs. also ...
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44 views

HowTo create an accurate constant-current dummy load using immersion heaters controlled by Arduino?

Given: variable sized nominal 3.2V LI/LFP battery cells, from little 18650 / 26650 cylindrical A123s up to large prismatics from CALB / Winston etc. the desire to capacity-test them off grid (no ...
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39 views

Setting gain on Improved Howland current source (best practice)

I understand that you can set the gain of an improved Howland by setting the the ratio of resistors \$R_2\$ and \$R_1\$ and/or the value of \$R_{\text{set}}\$. Is it better to leave the ratio of \$...
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43 views

Howland source, MAX current output?

How would one determine the maximum current output you could achieve from an improved Howland source given a specific Op-Amp? ie. What do I need to look at in the Opamps datasheet? (I am using a ...
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132 views

What's wrong with this PWM-controlled constant current sink?

T10 gets very hot and starts melting within 30s, even with a heat sink and values way below its rated 15A. Edit: I know it is not a true PWM controlled constant current, but that what I can do with ...
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54 views

Do I need a laser diode driver for this? (noobegginner)

I have a blue laser diode, with max specs of: 2.4w 2.2A 5.2V Currently, im using a ion power bank with a skinned usb wire to power it. The maximum current I measured from it is only 1.4A, and voltage ...
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36 views

Offset Voltage at Op Amp Inverting Terminal

I'm using ADA4350 as a transimpedance amplifier with various gains for feedback paths (30 ohms,3k,300k and 3 mega ohms respectively). When I give a constant current source of about 23mA as input to it,...
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40 views

Current limiter low voltage drop

I'm trying to understand the function of the constant current regulator CCR and the zener diode 1N5338. I do have more questions but these two components is probably a good start. I understand that a ...
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42 views

High Power LED Circuit Design & Constant Current Source Question/Feedback

I'm trying to design a dimmable LED circuit board. It's controlled by Arduino with its PWM signals. I'm new to electronics so I have some question regarding my design and knowledge on it. I've ...
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92 views

26 Led Array Component Identification and Failure Cause

I have the following LED lights. These lights keep failing on me. I'm suspecting that the DPAK(U1) component is failing but I have no clue what it is. The markings on the DPAK reads 5ZYl8GF6D. I'm ...
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59 views

What happens when transistor operates in saturation region for constant current source

I am learning about the constant current sources and I found this video What I dont understand is that, when the forward voltage of the LED is increased from 1.7V to 3.3V, and our Emitter voltage is ...
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How does a traditional CC/CV circuit work?

I went through an application note from Texas Instruments referenced as snva829 ( the link http://www.ti.com/lit/an/snva829/snva829.pdf page 2 and 3) where they have discussed superficially the ...
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63 views

High power opamp-based constant current source circuit

I am currently working on a high-power 28S lithium-ion charger for EV. I'm on a constant current stage, so you don't have to worry about all that balancing thing, I just want a constant flow of 15A ...
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97 views

Driving 34 White LEDs in Series with Linear CC Source with 110V Mains

I have 102 White LEDs in total and I want to drive them from the 110V rectified Mains in 34S 3P configuration. Here's the graph about the LEDs (Red Line). I want to pass only about 50mA ...
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0 - 70mA led driver

For a project, I want to detect the red part on the moving disk of Ferraris electricity meter. I want to do this with an Infrared LED and a phototransistor that receives the reflected light. The ...
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93 views

Meanwell LDH-45 LEDs Glowing When Controller is Off

I'm using a Meanwell LDH-45B-350 Dali driver for currently 4 Bridgelux BXRE-30G0800-D-73 LEDs with forward voltage of 18v at 350mA. The problem is when I switch off the driver, the LEDs still glow a ...
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1answer
73 views

Recommended design PWM-enabled driver for multiple 1W LEDs in series-and-parallel configuration?

A note on my background: I do have a degree in electrical engineering, but honestly I don't consider myself skilled enough to come up with designs from scratch, hence my post. Design Issue I wish to ...
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249 views

Constant Current and Constant voltage

I have this Power Supply There are two modes, Constant current and constant voltage. When does this two modes come into picture under which circumstances. Can someone explain?
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67 views

CV/CC with a single LM317?

In all designs that I could find they used two LM317, one for CC and another for CV. Is there a reason why no one used a circuit like this with only one LM317? simulate this circuit – Schematic ...
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66 views

How to protect a CONSTANT current DC motor from stalling?

What would be an efficient way to protect a DC motor that draws CONSTANT CURRENT (always 300mA) from self destroying when stalled for too long? Or is this even necessary on brushed DC motors? On other ...
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169 views

Voltage Controlled Current Source - help needed

I am designing a voltage controlled current generator for the currents in a range from 0 - 2.5mA. The load resistance is within the range of 0 - 5k Ohms. I decided to go with difference amplifier ...
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1answer
50 views

Constant current source for an alternating magnetic field of varying frequency and constant amplitude from a solenoid

The project I am working on requires me to oscillate my sensor. I am doing this by coating a ferromagnetic material on the sensor and applying a sinusoidally varying magnetic field. I was applying the ...
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2answers
87 views

How to fix this constant current drive circuit?

I have selected a constant current source to drive LCD in my design but doesn't work well, so I'd like someone to help me pinout where the problem is. The LCD backlight requirement is as below.The ...
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1answer
152 views

How to limit current while almost keeping voltage same

I am supposed to design a power supply to a project. I have 3 alternative power supply designs for this purpose. However, one of them sucks huge current while giving enough current. My design is given ...
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70 views

Bi-directional constant current using analog switch

I am trying to build a bi-directional constant current source with a h-bridge configuration. As you can see in the attached figure, I am controlling the direction of current on the load using PWM ...
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128 views

Driving a WS2815 12V LED strip with a CC+CV driver

I am selecting a driver/PSU to power a string of WS2815 12V LEDs. WS2815 datasheet here: http://www.world-semi.com/DownLoadFile/138 One option I am looking at to power these strips is the Mean ...
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2answers
83 views

How should I make a constant AC current source to drive an electromagnet?

The inductance of the electromagnet is about 0.05H and the resistance is under 50 Ohm and I need about 2 to 5 Amperes to drive it. I need to be able to change the amplitude and also the frequency at ...
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70 views

Pulsed DC current measurement using arduino and shunt resistor

I am currently working on a project ( to develop a constant current pulsed DC supply) in which current has to be measured using Arduino's analog input (Upto 20A) passing through a variable resistance ...
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36 views

EV charging and charging station

An EV battery first charges through CC(Contant Current) method and then through CV(Constant Voltage) method. So this way of charging is made sure by the circuitry on board the vehicle for Level 1 and ...
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2answers
239 views

Homemade Li-ion charger

I am trying to build a lithium battery charger (Li-Ion) for charging banks of 6s batteries of varying capacities (2-30Ah) from a varied DC input. Given that I need to supply CC/CV to charge these ...
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3answers
123 views

Dim LED lamp with constant current power supply using resistors

I own a really bright led lamp that I want to dim. It is powered by a constant current power supply that can supply 37mA between 11V to 17V. If my lamp is connected the voltage settles at 13.58V. ...
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1answer
93 views

Repairing an old Bench Power Supply

I have an old PS-303D from Conrad in use at home. Recently it showed a problem. If I measure with my multi from V- to V+, the voltage reading is correct, current and voltage regulation seems to work ...
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49 views

Calculating charge time of a large capacitor from a boost with a limited power source

I am trying to work out the math of what is the highest cap voltage or capacity I can have to charge from a boost topology in a given time from a source of 5V, 500mA. Here is a rough sketch of what I ...
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95 views

Constant current load circuit? (20 amp) [closed]

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
109 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
98 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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21 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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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
57 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
544 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
62 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
73 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
345 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
83 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
76 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
172 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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881 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
215 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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