Questions tagged [constant-current]
Questions regarding constant-current supplies, devices and applications, as opposed to constant-voltage supplies. The voltage can vary while the current remains the same. Common in LED lighting applications and battery charging.
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10-15 V input, 7-14 mA constant current output against changing resistive load from a 0-3.3 V signal
I have asked a similar question previously and got some great answers, however during testing, it transpired that there was another requirement that I had missed in order to satisfy some diagnostic ...
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Charging a lithium battery in CC/CV mode
First of all, I would like to charge my battery with a constant current. When my battery is charged to 4.2 V, I want to stop the constant-current charging and switch to CV mode.
My problem is the ...
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STCS05DR LED driver
I am trying to use the STCS05DR constant current LED driver IC by STMicro in my buck converter design to indicate input power with a 1206 red LED.
The input power is a variable DC battery source (...
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How can I make a constant current source for a CW laser diode?
I need to power a single CW laser diode with a constant current source. I have attached the datasheet of the laser. It is a 2.2-2.4V laser whicht operates at 80mA at full brightness.
I see a lot of ...
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Power/drive unknown amount and colors of LEDs using DC voltage from AA batteries
The Plan
In a 3d printed game board tiles that I'm designing, there are game pieces that will be placed down by players on specified locations. I'd like to have these pieces light up with LEDs. I've ...
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Photodiode circuit to compensate for LED temperature drift
I'm trying to create a stable light source using 5000K white LEDs. In researching this I've discovered that LEDs drift with temperature by a non-negligible amount. Further research leads me to believe ...
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Which resistor can be replaced by a potentiometer to adjust the current on this power supply which uses a FAN4803 chip?
The power supply schematic:
Here is the FAN4803 IC datasheet:
https://www.mouser.com/datasheet/2/308/FAN4803-1-1191942.pdf
ISENSE
This pin ties to a resistor or current sense transformer which
...
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Current source circuit components
I want to make a constant current driver for a laser diode (500 mA max.) based on the circuit shown below:
Here is my version:
In my case D2 and D3 represent the laser diode. There is a NC relay and ...
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NTC resistor to balance ambient temperature change on precision current controlled lamp
I use a constant current control design to control the current through the halogen lamp, which typically runs at 800-900 mA
Resistor MPN: PCS2512DR1000ET
DAC: MCP4725
simulate this circuit – ...
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How will a diode affect a constant-current NiMH charging circuit?
Consider the following constant-current battery charging circuit (simplified for the purposes of exposition):
My understanding is that the current through the diode and battery will be held at 0.24 A ...
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Simulating the feedback network in constant-current step-down converter
I'm analysing a (real) step-down converter which gives a constant-current output and want help in how to simulate the feedback circuit, in the abstract.
The real circuit has an ST L5973AD (datasheet), ...
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Can I indefinitely "trickle" charge NiMH batteries with a constant current?
[Note: Various answers to other questions address this, but I cannot find
another question focused on just this. This is my attempt to create a
definitive place for answers to this.
[If at all ...
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LM317 adjustable current regulator for LED
I am driving a 10 W LED from a LM317 regulator. With a variable resistor in between the OUT and ADJ pins of the LM317, I can easily get an adjustable current source (20-350 mA). However, I need to ...
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Constant voltage LED driver to constant current conversion
I have 12 pieces of wrong supplied Meanwell LPV-35-24 LED drivers which are of constant voltage type onboard a vessel. Our lighting fixtures are using constant current drivers and I run out of spares. ...
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How does this constant current circuit work?
I'm trying to develop a constant current source capable of outputting 10mA regardless of impedance changes. While I was looking into improved howland pumps as a potential solution, I came across this ...
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Control high-power LED by LT3080 and PWM
I am a beginner in electronic circuits, so could someone check if my circuits design is correct?
What I want to achieve is as follows;
Light up 5 high-power LEDs (EDC780D-1100)
Vf = 2.1 V
If = 800 ...
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Constant Current Source Charger
I want to create a constant current charger of 3 A. The battery upper charge level is 54.6 V (battery is 6.6 Ah, 13S3P, 35 to 54.6 V, nominal 48 V).The input is 48 V, 6.6 A from a DC adapter. I plan ...
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An adjustable (MCU) current controlled power source
Background:
Source: Likely a boost converter IC (30v)
Load: max 4mA (with 0.1mA accuracy), resistance varies (~1k-100k ohms).
Need an MCU to control the constant-current output, ideally it can also ...
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I have limited understanding of circuit design and am thinking I need a constant current circuit to power 4x specialised LEDs in series/parallel
I have 2 strings of 4 LEDs connected in series and am thinking a constant current circuit due to the voltage drop and forward current requirements. Each LED has \$V_f\$ of 6.1v and requires \$I_f\$ ...
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Boost Converter With Constant Current Source
I want to design boost converter but not like general converter. This boost converter will be include constant current source feature.
I designed buck converter version before
**
I used LM2596 and ...
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UC3843 doesn't work as expected
I tried to implement a constant current driver "May be constant power driver" using a UC3843, simply by disabling the EA by pulling it down to GND and clamping the COMP voltage between 1.4V ~...
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Efficient and cost-effective way to limit current across an LED strip
I am currently attempting to build a DIY driver board to power the backlight of an LM270WQ1 panel.
Per the datasheet, there are six LED strips, each of which take 36V @ 350mA.
The adapter board that ...
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How to select the proper LEDs for light fixture
This light fixture has 3 heads with 15 LEDs for each head. The 3 heads are connected in series. In each head, there are 3 sets of 5 LEDs connected in parallel. The 3 LED sets of 5 for each head are ...
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Why make second stage current larger than input stage current in op-amp?
When people speak about the slew-rate of a Miller-compensated op-amp, the usual derivation is that the slew rate is approximately the input tail current divided by the Miller capacitance. E.g. here (...
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Workings of single constant-current source with four MOSFET-switched LEDs
Background
I have several hundred RGB+White LED lights which are controlled by a driver circuit which is no longer manufactured, and trying to plan some maintenance and possible replacement of the ...
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Basic circuit advice to control a solenoid at different currents
I am looking to control a solenoid at approx 1.4 A, 0.7 A, and 0 A with a rocker switch and will need constant current capable of 100% duty cycle at these currents.
The supply voltage will be a 12 V ...
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Sanity checking an LM2596-ADJ constant current supply design for driving LEDs
I've designed, in simulation, an adjustable constant-current supply based on an LM2596-ADJ buck converter IC.
I chose STW8B12C LEDs for simulation because three of them in series roughly matches up ...
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COB LED unwanted blinking
I'm testing a Cree CXB1304 powered by a constant current driver Meanwell LPV-35-36
This setup makes the LED blink regularly every 2 secs, as I've read this occurs when the driver has insufficient ...
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Need some component to allow 17 A pulses at 10 Hz, but clamp or trip if the current goes continuous
I would like to protect some equipment that gets damaged when it continuously pulls 17 A for more than 2 seconds. I would like to react to the current within around 1 second.
The supply voltage is 48V ...
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How to choose suitable LED power supply
Can I replace an LED power supply with this output: DC 50~57 V, 280~300 mA
with a new supply with this output: DC 45~85 V, 300 mA ±5% ?
In other words, does it matter that the output voltage has a ...
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Why does current decrease in CC mode before reaching 4.2V in CCCV method for 18650 Li-ion charging?
I'm trying to charge 18650 cells from LG which have a capacity of 3200 mAh. I read the datasheet of the cells and it said 4.2 V and 0.5C of nominal charging. I'm not an expert so I did some research ...
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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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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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How to make 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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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