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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Cable jack melted

I've build this circuit: My power supply is 12 V, 4 A and my load is rated at 1 A and the melting point of the cable I'm using is 300 F. I found the cable has melted at the point of contact between ...
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3 votes
3 answers
463 views

Need help with understanding constant current control circuit

I am an electronics noob struggling to understand a circuit I have reverse-engineered from a circuit board. The circuit will power up a spectral lamp with a current control from 0-25 mA. From what I ...
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0 answers
19 views

Constant current limiting device between lead-acid battery and MPPT inverter [closed]

My goal is to create a small-scale grid-tied standalone battery backup system using (used) car batteries. It would physically switch between charging from and discharging to the grid. I'm aiming for ...
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-3 votes
1 answer
85 views

Can LEDs produce light like incandescent light? [closed]

LED light flickers around 100 Hz and is caused by rectifying AC power. How can LEDs be made to emit constant light that comes from an incandescent element which does not flicker?
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3 answers
70 views

Using Jfet as constant current source to drive a BJT

The circuit diagram below shows two simple voltage regulators, one of them is driven by constant current source using a Jfet and the second one also providing a constant current because the voltage is ...
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0 answers
31 views

Feedback circuit for implementing CC/CV in DC/DC switching circuits

My goal is to design a 10s lithium battery charger with the ability to vary the output current depending on what power adapter is used. For this I want to use the LTC3786 boost converter and the ...
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0 votes
1 answer
42 views

Battery Charging with Two Constant Current Power Supplies in Parallel

first time asker so be gentle if this is dumb. I'm using this LED Driver (constant current, output range 143-286v) to balance charge a high voltage hybrid vehicle battery at very low current, and it ...
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2 votes
3 answers
78 views

LM1085 constant current mode: changing input voltage deviates the ADJ pin in a non-linear fashion

I used the below schematic to output a constant current (~0.92 A) on the RLoad. I turn on/off the N-channel mosfet: simulate this circuit – Schematic created using CircuitLab While current ...
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-2 votes
1 answer
43 views

Reliable constant current DC/DC converter [closed]

I am looking for a CC converter to charge my lithium battery. Most DC/DC converters with CC/CV are Chinese made with very poor reliability. I need something like this to convert 8-15V to 15V CC at ~5A....
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0 votes
1 answer
35 views

Why does this ESC and BLDC Motor work together?

I have a BLDC motor, and I have an ESC to control it. These 2 are commonly bought together on Amazon. The ESC is rated at 50 Amps continuous with a max current of 150 Amps. I am confused how this BLDC ...
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  • 333
0 votes
2 answers
76 views

Lower voltage limit of constant current driver

I am looking for a constant current driver with rather low current (100-200mA) to drive COB LEDs (approx 34V). I found several which give an output voltage range, e.g. 12 W input: 220 Vac 50 Hz output:...
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-1 votes
1 answer
51 views

High current flow in voltage regulation using TL494

I am using the given schematic for voltage regulation. When I’m not given the feedback, that is point A and B is not connected, then m getting a pulse of 35 % duty cycle of 0-12 V. But when I’m ...
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1 vote
0 answers
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Building a linear current regulator from a 12V 50A SMPS using a BJT array and a DAC

I have an application where I need a digitally controlled constant current power supply capable of currents up to 50A. I have made a digitally controlled constant current power supply in the past, but ...
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2 votes
1 answer
53 views

How to interpret LED driver output labels?

I am looking to drive an LED panel with an alternative driver to better suit my application, but first need to understand the existing one which does not seem to match the same labelling convention as ...
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14 votes
3 answers
3k views

How do constant current constant voltage devices work?

First of all can a device that is constant current also be at the same time constant voltage? In my head I just could not grasp how this device can work. Individually I understand how it works, ...
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1 vote
1 answer
81 views

How to compute component values for current-controlled 555-based oscillator?

I am building a project where I plan to have a current controlled oscillator based on a 555. The oscillator is controlled using current source I1 (a current mirror) charging capacitor C2 in lieu of ...
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  • 490
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0 answers
36 views

Constant current power supply and 4 unique loads that I would like to individually control via PWM. Loads are to be driven at varying currents

I have a 1400ma constant current power supply (plenty of power to drive all loads at 100% duty), and I want to PWM 4 separate loads that are all driven optimally at either 350ma, 700ma, or 1400ma. The ...
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1 vote
4 answers
181 views

Does a low-enough leakage-level battery discharge cause highly asymmetric cell discharge?

A Tale of Two Batteries This is concerning two different 6-volt lantern batteries that have behaved the same exact way (I believe.) Here is a datasheet for the type of battery, a Rayovac # 941 ...
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0 votes
0 answers
26 views

Current in inductors of emi filter

I am currently working on an EMI filter for a led driver (constant current). Here you can find the according schematic: My question now is, which (if any) current is going through the inductors/have ...
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0 answers
43 views

voltage amplifier design feed by current source

I want to connect electret microphone with long wire to receiver. Usual way is to use balance line technology, but it can be expensive, then I've opted to use CCLD Constant Current Line Drive ...
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0 votes
0 answers
53 views

EMI Filter - current in inductors / part selection

I want to use a NLDD-1400H LED Driver as constant current source with 1.4A ouput. On the last page of the datasheet there are information about an EMI Filter, I want to use. Here is the schematic: ...
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0 votes
1 answer
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LIthium 18650 discharge voltage

I am capacity testing 18650 batteries from old laptops using constant current, previously I used 2.8V as discharge/cutoff voltage but now raised the value to 3.0V Discharge current is 1Amp. I know ...
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1 vote
1 answer
86 views

How can I limit input current to a raspberry Pi to 2 amps from a high current battery?

The circuit I currently have consists of a motor circuit and a raspberry pi circuit connected to the same battery. (2 series circuits from the same battery). The problem is that during idle motor, a ...
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0 votes
0 answers
55 views

Trying to understand RC circuit with alternate voltage in LM3409 LED driver data sheet

I've been working on designing a circuit that uses the shunt-FET approach documented in the LM3409 data sheet, wherein a MOSFET is place parallel to the LED load, and is driven by a PWM signal to ...
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  • 361
0 votes
1 answer
270 views

50 watt brick LED , JW19818 chip

The JW19818 chip says 4 watt power. There are 50 watt LEDs connected to 2 chips in this schematic. Can anyone explain?
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0 votes
0 answers
24 views

Is this current and resistance OK for this CC-CV IC and battery?

I want to charge/recharge this battery in 'fast charge mode' which corresponds to supplying a 60 mA of current using this IC which (according to the equation on page 15 of the IC's datasheet) requires ...
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0 votes
1 answer
57 views

Driving LED module using CC driver

I am using 3x10 COB LED along with CC driver that is 960 mA, 30-35 V and the connection type is series-parallel. Now the issue is if one of my string fails so will it add up to the remaining LED or no?...
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0 votes
0 answers
90 views

Why is the op-amp not regulating voltage in this circuit?

I'm a first timer here, I hope I can explain my problem as clearly as possible. I need to apply a current source to measure the voltage on a load for a given current. Since I don't really have many ...
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0 votes
1 answer
58 views

Inductor position in low side buck converter

I am designing a PCB to control an RGBW-LED. To provide a regualted current for each color I am using the LM3407 buck converter from TI. The buck converter is powered with 12V and is configured to ...
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0 votes
3 answers
66 views

Constant current source and halogen light bulb

What happens to a halogen light bulb specified at 10V DC and 1A (10W) when you connect it to a constant current source that runs on 24V DC and can be regulated up to 0,8A. You would need to set the ...
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0 votes
0 answers
38 views

Constant current battery charger with ac/mains cutoff

I need to build or purchase, an efficient 48 V battery AC to DC charger for my home solar system, which can charge the battery in constant current mode using grid power and once fully charged it ...
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0 votes
1 answer
104 views

Can anybody help identity what Q1 and Q2 in this circuit are doing?

I'm debugging a failed board for a humidity sensing extractor fan. RP1 is the humidity sensor. Q1 and Q2 (SOT-23) look like some sort of dual current mirror, but I don't understand this configuration ...
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1 vote
2 answers
79 views

Is there a CC source that is able to invert the voltage? Which one?

Lets say I have a CC source and set it to 10 mA and connect it to a coil. If I induce a reverse voltage in the coil with a magnet, the CC source should regulate the current to 10 mA by increasing the ...
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0 votes
0 answers
87 views

High current (~100A) linear regulation

Hello I need to drive resistive load of 0.25 OHM. I have 24V 100A power source available. I use computer to measure operating conditions, but as response I need to control current and by this ...
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0 votes
3 answers
209 views

Probing with oscilloscope fixes noisy circuit

I'm trying to debug very strange behavior I'm seeing while I'm trying to breadboard out a circuit to test the passive values for an LED driver I'm designing. I am designing for a 28 V input and a 25.4 ...
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1 vote
1 answer
66 views

Switching Multiple Constant Current Regulators

I'm looking to setup a grow light system but I'm a bit of a beginner. My aim is to be able to turn on/off two series of LEDs from an Arduino Uno. At the moment I have two constant current regulators (...
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0 votes
0 answers
44 views

Handle fast signal using OpAmps: ADA4891 - 2

Relating to "Handle fast signal using OpAmps: ADA4891". I added a high-side switch and a constant-current circuit. However, the hold voltage immediately drops when switching the high-side ...
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0 votes
1 answer
106 views

Can a constant-current LED driver with a reference resistor be dimmed?

I have a scenario similar to Tuning a constant-current LED driver, per channel: also considering use of two TLC5928 but with If <= 20 mA per channel 28 channels have Vf ~ 8V < 9.6V 4 channels ...
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1 vote
2 answers
69 views

How can the NSI45020T1G claim to "turn on immediately"?

The On Semi NSI45020T1G, a simple two-terminal inline current regulator, claims in at least two places that it "turns on immediately". However, it cites a capacitance between 2.5 and 2.7 pF....
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  • 3,022
0 votes
3 answers
181 views

Balancing current with resistors when driving parallel strings of series LEDs with constant current

I'm designing a light source that will employ a grid of LED emitters powered by constant current drivers. The LEDs will be laid out in a parallel/series combination, in rows of 8 emitters in series, ...
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  • 361
5 votes
1 answer
342 views

UC3843 PWM Duty Cycle Variation With Temperature

I'm trying to implement a constant current solenoid driver (it's more of a constant wattage pwm driver, current changes with supply voltage which is fine) using UC3843 PWM driver. I'm using the ...
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0 votes
2 answers
81 views

How to regulate battery voltage

I am using a LiFePo4 battery 26.5 V, 18 Ah in my project where I am using three DC motors I need a constant voltage for my motors but as the load on one of the motors increases it affects the speed of ...
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3 votes
2 answers
151 views

Controlling High Current LEDs with an ATmega328

I am trying to build a circuit design that has 4 LEDs that will need more current than the ATmega328 can give out. I will want the LEDs in parallel so I can control them all individually. Because they ...
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1 vote
1 answer
67 views

LED Dimmer circuit accidentally damaged

I am currently working on a prototype system that uses these 3w LED drivers (I am using the one with the picture at the right). It uses the XL4001E1 CC DC-DC converter capable of outputting 700mA to ...
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4 votes
4 answers
558 views

LM317 as current regulator - problem

I'm driving an LM317T from a variable PSU and using it to run 6 x 1W 300mA LEDs in series, approx 3.5v each. The Output pin goes to a 4.7R resistor then to the LEDs, and the Adjust pin is connected to ...
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0 votes
1 answer
75 views

High-power LED Shunt Protection using Zener diodes with constant-current LED Driver

I'm about to build a custom high-power lamp. The lamp will operate a total of 60 high-power LEDs (operating point: 2800mA @3.1V per led) connected in series. The original plan was to have the LEDs ...
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2 votes
2 answers
290 views

Super-capacitors to heat resistive wire

I am looking for help/insight into the feasibility of using the stored energy in supercaps to heat a short length of nichrome wire, or a vape coil. I have nichrome wire that is 0.040 size, at 0.408 ...
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1 vote
1 answer
78 views

Knowledge requested for WS2811 Based RGB LED driver Module

Design of LED Module based on WS2811 LED driver IC (Only Red-channel is shown). To the right of the schematic you will find a simple, cheap and robust constant current LED driver. The current for the ...
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-1 votes
3 answers
662 views

Use LM2596 as constant current source

I am trying to make a constant current of about 0.8A to control a 13W LED using the LM2596 buck regulator. My idea is to use a variable resistor to connect as 2 pictures following to get that ...
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1 vote
0 answers
106 views

Using constant current and constant voltage power supply with LED strips

I have a Meanwell 12V power supply (ELG-200-12) which is constant voltage and constant current. Note 2: I want to power t one 5 meter 12V LED strip that consume 11.52W/m with it. The specifications ...
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