Questions tagged [current-limiting]
Current limiting is the practice in electrical or electronic circuits of imposing an upper limit on the current that may be delivered to a load with the purpose of protecting the circuit generating or transmitting the current from harmful effects due to a short-circuit or similar problem in the load.
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How does a wallbox limit the charging current?
There are wallboxes (for EV charging) where the user can choose to set an upper limit for the charging current. This is useful if the user's PV doesn't deliver enough power. It allows the user to ...
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Which reverse polarity protection is better and why?
You can find two such circuits using a diode that protects against reverse polarity, i.e. against wrong power connection.
I wonder what is the point of using the D2 diode, since the current flowing ...
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What are the drawbacks of using a voltage regulator as a constant current source?
There are similar questions asked, but none address this question so specifically.
It is, quite simply the title:
What are the drawbacks/disadvantages of using a voltage regulator as a constant ...
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USB inrush current limiting, charging super capacitor
I am trying to charge a supercap over USB. I understand I need to limit the current (ref: usb.org)
This has been discussed a lot here, for example: here and here, but I believe my requirements are a ...
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Need a way to regulate current and voltage in CCCV but portable
I have a project in embedded systems that requires charging a 14S lipo battery from a 60V regulator/alternator supply (an RC vehicle), the lipo gets to 99% capacity around 58.8V and the circuit limit ...
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Self-oscillating switching current limiter
I have a first draft design for a self-oscillating switching current regulator. It appears to work in simulation, but I would like to know if there are any concerns about this design that might show ...
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Calculating current limiting resistor for high current circuits
I am designing a simple three-phase inverter to begin working in power electronics. I have no experience in power electronics and minor experience designing circuits. While working on it, I ...
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Understanding USB3.0 over-current detection circuit
I'm trying to understand how the following over-current protection circuit works:
the way I understand this, as long as +VBUS_USB3_P0 = 5V and it's equal to +5V_ALW, there is no current current going ...
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Can I use PPTC fuses instead of light bulbs to make an adjustable A.C. current limiter?
In Adjustable-ac-current-limiter-for-output-of-variac-for-safe-circuit-testing, I asked about alternatives to using incandescent light bulbs to make an adjustable A.C. current limiter. The challenge ...
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LTspice current regulator analysis with MOSFETs and BJT
I ran the transient analysis for the this circuit with NMOS and NPN respectively. Once with the NPN BJT, the results look reasonable. The current through R1 is about 20mA. When I change to NMOS, the ...
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What is the current industry practice regarding the impact of current-limiting fuses on arc flash calculations?
Suppose you have a panel. The arc flash incident energy for this panel is computed based largely on the available short-circuit current (SCCA) to the panel, and the protective devices upstream of the ...
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Constant Current Charger
I have done a simple charger by using a opamp UA741 and a current limiter. The current limit method is using 2 transistors and a resistor to limit at 3A. However, this current limit was not limit the ...
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Building the Error amplifier circuit part of UC3843
I am trying to build an error amplifier circuit on PSIM almost identical to the
In the datasheet, they used
Now, I want to ask in what ways is different than a normal Op-Amp element in PSIM.
...
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RC circuit oscillator [closed]
I want to make a simple RC oscillator circuit that produces waveforms of
How can I do so?
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How to limit current going into DC/DC
In my project, I am using 12 solar cells in series as a power source. This is the link to the cell. Doing that will give me a power source of (3.6W * 12 = 43.2W) maximum and output voltage is (0.6 * ...
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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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Are there still practical modern uses for large through-hole resistors?
When teaching electronics to college students, we often use these large 1 W cylindrical resistors - not because we need the wattage rating, but because they are easy to handle and read the color code ...
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Calculating resistors in circuit with optocoupler and triac
I'm trying to build circuit with optocoupler and triac, but i dont know how to calculate R2.
For R1 it was easy, since Led Trigger Current is 15mA-30mA, so with 330Ω and 5V i will get 15mA (or am i ...
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How to control level of power consumed by microwave from the transformer [closed]
Given the same load on the output (secondary) of a transformer, the input is mains voltage, and that I don't want to try messing about with the transformer windings at all, how can one control the ...
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AC current limiter in a circuit
I have the following schematic of a circuit using an AD8652 op-amp.
I need to limit the output current to 5mA.
If the output current is more then it should reduce the voltage. Can someone suggest a ...
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How to design/build a relay-triggered "crowbar" circuit?
(This is a continuation of Failsafe for relay contact welding.)
I'm trying to wrap my head around something like a "crowbar" circuit, only, instead of tripping on over-voltage, it should ...
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Garden windmill power generation
For the past year or so I have been 3D printing various windmill designs for my garden just as experiments and ornaments. Almost without exception, everybody who sees them asks me when I am going to ...
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Increasing only current using LM317
For the LM317 there is a precision current regulator circuit. This circuit uses an LM317 and only one resistor between the out and adjust pins. The operation of this circuit completely satisfies me, ...
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Efficiently use a power supply with limited current (24 V, 6 mA, Mbus)
I'm trying to make a slave device that gets power from a bus - per spec, I am allowed to draw 24 V, 6 mA maximum (the bus goes to 36 V sometimes, and under certain circumstances I'd be allowed to draw ...
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Current limiting resistors and voltage dividers
I was once told that current and voltage is like a water in a river, the speed of the water can be likened to the voltage and the current is the width of the river. However, my confusion is when it ...
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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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Should I use PWM in addition to series resistor to limit current for battery charging?
I asked a previous question about whether a series resistor would be adequate for limiting the current for battery charging:
Limit battery charging current with simple resistor?
For some background: I'...
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Foldback current limiting in RC servo application
Background: A 7.4V 2Ah battery (LP-E6 from Canon) powers our system (camera/laser mounted on a one-axi gimbal). The gimbal motor is an RC servo (HPS AA701 from Futaba) connected directly to the ...
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How to handle a current load that is *just* outside my 12V power supply's limits
I have a portable diesel heater which runs on 12V. When the heater starts, it warms a glow plug that draws somewhere in the range of 9-10A until the plug is hot (figure, roughly 1 min), after which ...
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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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Adjustable current limit control
How can I add an adjustable current limit control to the circuit below? Please explain with schematic.
The output value doesn't matter to me; it is important for me to learn how to change and control ...
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Reduce current pull in circuit
I have a Li-po battery (or any portable power source) providing 3.7 V output voltage. I want to connect a very small motor to it and have it power it for as long as possible. Here is the catch: the ...
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Current limit in low-power device
I have a circuit that is powered up by six AA batteries. I am applying for safety certification, and one of the requirements is that the max. current the circuit board can receive is 1.5 A.
I already ...
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Protecting an op-amp's 0-10 V, 5 mA outputs against 24 VAC being connected to them
I have a circuit with four 0-10 V, 5 mA output channels on a PCB designed to work for ventilation, where the output valves are powered by 24 VAC. It is to resolve a problem we have at work with 350 ...
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Light bulb as limit, to what is current limited to?
I was wondering, if I use a light bulb as a current limiter when working with some electronic device, in case of a short circuit - what determines the current that is allowed to pass to the electronic ...
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Power supply circuits to supply specific voltage with current limitations
I have an old sensor that requires 200mA at 5v DC, but it does not have any overcurrent protections and will blow a capacitor if the current is too high. Is there some kind of current limiter circuit ...
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Control the current of a power supply using another variable power supply connected in series
While disassembling a little electric oven (rated for 1300W at 230V), I scavenged one of the heating elements inside, which I measured its resistance to be about 40 Ohms (let's call it ...
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Interpreting datasheet for switching regulator
New to this and designing my first non-trivial circuit. I'll be using an ATMEGA168 and plan to run it at 3.3v/10MHz to maximize compatibility with other components.
I'll be placing this into some ...
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Megger manual warning clarification
When a manual of a Megger warns:
The measurement time must not
exceed 10 seconds if the measured resistance is less than 1.5 MΩ at 500 VDC position or less than 5 MΩ at 1000 VDC position"
The ...
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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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Component requires specific voltage and current but the math doesn't add up
I'm trying to get an old soviet era cathode ray tube working.
On the data sheet it says the heating element needs between 5.7V and 6.9V, and between 0.54A and 0.66A, but I've measured the resistance ...
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Relay contact protection against 24V 2-pole brushed DC motor inrush current
I'm driving a 24V DC motor applied to a small gearbox. Motor control is via (2) 8A rated PCB mount relays that provide motor power as well as direction control. Motor inrush is rated at 8A for 10-20ms ...
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Why is there a lot of current variation at the output of a buck when a battery is connected at the output?
I am looking to simulate a buck DC-DC that charges a battery pack. In LTspice when I connect a battery at the output there is a lot of current variation, but if I connect a resistive load the current ...
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Remove over-current protection from 5 VDC common mobile/router charger
When the negative and positive terminals are crossed the current stops then recovers again. I am trying to figure out what can be done to get full potential of the charger by removing this protection. ...
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Why is the MOSFET current taking time to rise in linear mode of operation?
In the below current limiter circuit, why is the MOSFET current rising slowly?
Shouldn't the MOSFET current follow the equation \$i_D=\kappa(V_{GS}-V_{th})^2\$?
Ref: How to Make Linear Mode Work
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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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PWM MOSFET choice to power large DC motor and control inrush current
I have a 4 hp, 90 VDC, 12A @ 5200 RPM treadmill motor and a 80 V, 6 Ah lithium battery.
The project is to use this motor to convert a lawn riding mower to electric using a tractor transmission and ...
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Circuit design options for 58V lithium battery charger
I have an Echo 58 volt chainsaw and the battery charger has malfunctioned so that it no longer charges the battery pack. I have been charging it by using a 2A current limited lab power supply set to ...
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Voltage-controlled current limiter as a solar battery sink [closed]
Excess solar power needs to be dumped into a lithium based battery (load). The battery's charging voltage is 54 V. The battery has protection for over and under voltage and upper current limt and that ...
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How do I lower current usage on a 12 VDC fan hooked to a battery without a rheostat?
I have a 12 V fan hooked to a battery. I also have a solar charger to charge the battery. The issue I have is that the fan runs very fast when the battery is fully charged and runs the battery down ...
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