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.

Filter by
Sorted by
Tagged with
3
votes
2answers
82 views

Need to limit current to maximum 1.6A

I need to build a current limiting circuit in order to protect a circuit board. It is for a solar power application. Currently the circuit board only can handle 1.6 amperes but the solar panels that ...
1
vote
1answer
67 views

How can I restrict current to 12 amperes on a 12V circuit?

What is the best way to restrict the current a motor draws? I am using a 12V DC motor which unrestricted (i.e. no current restriction) draws around 18 amperes. I need this to be limited to 12 amperes ...
0
votes
1answer
50 views

Voltage and current controller problem

simulate this circuit – Schematic created using CircuitLab For a specific project , I need to create a Voltage-Current controller circuit that will be able to control the flow of Current and the ...
0
votes
0answers
35 views

Is there a power strip/PDU that can switch off electrical outlets (on the strip) if the total combined power draw exceeds a predefined limit? [closed]

I need to run six 240v kitchen appliances at any one time, from a 12V battery(s). I want to spend as little money as possible on batteries and the inverter. The appliances are each 1000w, but they ...
0
votes
1answer
84 views

Allow current draw only when it is over a certain value

Is there a way to passively allow the current to flow over a certain amount? i.e., if it is a small parasitic drain, ignore it, but if it is something larger like starting an engine, allow it. Almost ...
0
votes
2answers
79 views

voltage regulators: How does Ohm's law apply here (and how not to fry an ams1117)

Very basic noob question here, asking for an analogy rather than a 'it's law xy': I used an ams1117, 2.5V, sot223. To test it, I used an usb cable 5V and plugged it into my phone charger (rated 2A) ...
0
votes
0answers
56 views

Op-amp limiter circuit with Zener diodes

I am new to electronics and we have this course for university. What is the theoretical analysis for this circuit? How can I find the Vin and the Vout? I think there is more than one case. The circuit ...
2
votes
1answer
90 views

Help explain the math behind this high-side current limiting circuit

I was playing around with my first attempt at building a high side current limiting circuit. I was expecting a lot of trial and error to get anything functional, but low and behold my first try ...
-2
votes
5answers
169 views

Why can't we light up 4x 3V leds with a 12V power supply?

To calculate the resistor to limit the current, if we use R=P/I² formula, it gives us wrong parameters rather than using V=RxI, so the 12V-12V is 0 and the P formula gives us nothing. Why is it so?
0
votes
1answer
65 views

Pulling down positive voltage to limit negative voltage current

Below circuit is the negative rail of a dual tracking power supply. How do I detect voltage drop on Node1 and pull down Node2 to limit the current without using an op-amp? Edit: I just want to define ...
1
vote
10answers
717 views

Does current in a circuit change when it passes through a resistor?

When I power an LED (a small one used as an indicator) with a 5VDC, it blows up, but when I use a resistor in series with the LED, it lights. My instructor calls this resistor a current limiting ...
0
votes
1answer
82 views

Constant current limiting circuit

Can someone help me understand the working of this circuit: My questions : Please explain me how this circuit will work in its entire operation range. I am not able to understand the purpose of the ...
0
votes
2answers
458 views

Why does current flow through 1M resistor in this case?

I asked a question about protecting a circuit from current spikes from a piezo electric device: Protecting circuit from piezoelectric disc voltage spike. Someone graciously provided me with a solution ...
0
votes
1answer
69 views

Adjustable CC/CV supply with voltage and current limiting having no output voltage at low voltage levels?

Im trying to create a power supply with an addjustable output between 0-12V or 0-3A (CV and CC adjustable). To make sure that the components don’t get damaged I'm trying to implement a protection for ...
1
vote
1answer
56 views

LED strange behavior

I am analyzing ways to make a current limiting circuit, and here I'm having an unexpected problem. The schematic is as follows: The problem I am encountering is twofold: Even when node Vin is ...
1
vote
1answer
51 views

Do eFuses work with AC current?

I was wondering if integrated eFuse solutions exist that are designed to protect a low voltage AC bus. In my application I would like to replace a 2A PTC that protects a 24VAC bus but I cannot find an ...
0
votes
2answers
47 views

How to limit regenerative braking charge current into 48 V DC Battery?

I have a 48 V DC battery which supplies more or less constant current (70 A) to the motors. When the motion direction is reversed, the motors start working as generators and the battery is being ...
1
vote
0answers
34 views

High efficiency pwm current limiter for charging supercap from alkaline battery

I'm designing device which uses two alkaline C-batteries in series as power source, and sends SMS messages using SIM800. On average 1 message per day is sent. Goal is to maximize battery life. Allowed ...
2
votes
1answer
93 views

Low side current sense output waveform

I am trying to build low side current sense amplifier for my motor drive (1 kW BLDC trapezoidal control.) Before that I get confused with the current waveform of BLDC drive in low side. My application ...
3
votes
2answers
73 views

Boosting load current of voltage regulator

I'm trying to connect little 3v LEDs to a motorcycle's alternator and i want to regulate the voltage of it to 3 volts so the LEDs don't burn up the alternator gives off 2.5 volts and over with 3 amps ...
1
vote
0answers
43 views

Use of resistors on signal lines of serial to parallel shift register

I have recently come across a circuit with a serial to parallel shift register(HEF4094B), and Vcc 12V. I could see that resistors are connected in series to the signal pins(OE, STR, DATA, CP). 2.2kΩ ...
2
votes
2answers
118 views

Does a BJT optocoupler have an inherently short circuit proof output?

I want to use an NPN optocoupler (ACPL-214) to drive an offboard relay. I know how to size the input resistor to limit the LED current to 20mA. This will cause the output current to be in a certain ...
0
votes
0answers
66 views

Trying to understand why voltage supplies have high in-rush current

I have a pair of buck switching converters in a circuit, the LM2673 and the LM2679. However, the LM2679 is being used in a buck-boost configuration as shown in this app note, AN-1157, and I'm ...
1
vote
2answers
49 views

Can a DC CC power supply be used for current limiting in a circuit with a battery in series

In circuit #1 I showed typical adjustable power supply usage it can limit voltage and current, all good. It got me thinking. Let's say due to some reasons I can't replace battery with a power supply ...
0
votes
1answer
61 views

way to calculate the draw limit on a battery

Is there a way to way to calculate the draw limit on a battery, using any of Amp-Hour, C-Rating, etc... values to solve for the unknown? If so how do you do it?
0
votes
0answers
44 views

Control capacitor charge current with a GPIO?

I have drawn the following schematic: Vp/Vm are +/-12V rails. The capacitor charges through R1. A 3.3V pulse is produced at regular intervals on an MCU GPIO to turn Q1 "on", short C1 and ...
0
votes
0answers
23 views

Max Charging Current for AGM batteries in parallel

I have 3 identical 125ah AGM deep-cycle batteries, all purchased at the same time. They will be charged with solar, through a charge controller. I have them connected together in parallel. They are ...
0
votes
0answers
57 views

Voltage subtractor using MOSFET

I am new to this site and maybe I won't ask a good question but anyway. I have come up with a voltage subtractor using two MOSFETs and a voltage divider well sort of. simulate this circuit – ...
1
vote
3answers
176 views

Hi! I would like to connect my LED lights (Vaxmyra from IKEA) designed for 24V system into my 12V system, do I need a current limiting resistor?

I bought these VAXMYRA LEDs thinking they were made for 12V but apparently they need to be feeded 24V. Supposedly I'll have to install a 24V DC step-up converter, but this device can deliver up to 3A ...
0
votes
3answers
86 views

Oscillations in parallel-RLC network with a limiting VCCS

Here is a parallel-RLC network (where G = 1/R is the admittance) with a limiting VCCS. The characteristic of the VCCS is shown in Fig (b), where the slope is G1. The problem asked is as follows: Find ...
1
vote
2answers
107 views

Current limiting circuit understanding

I have found this circuit which is supposed to be a current-limiting circuit: simulate this circuit – Schematic created using CircuitLab 'R1 is used as a current's resistor. It monitors the ...
1
vote
1answer
46 views

MOSFETs current regulators 1 input

Can we use a MOSFET to act like a single inout current regulator? Here is my idea. simulate this circuit – Schematic created using CircuitLab If the voltage on the input is greater than the ...
0
votes
0answers
17 views

Solar Low Current Disconnect Options

I've built a system which allows me to remotely control a well pump which is directly connected to 24v solar array. There is a regulated battery bank/inverter, but it's farther away, and the pump is ...
6
votes
5answers
1k views

What polyfuses protect USB ports in a typical modern PC?

I would like to know what is the typical rating of a polyfuse used on modern PCs (desktop or laptop) with USB 2.0 and 3.0. TE Connectivity apparently recommended in 2011 that a single USB 2.0 port (...
0
votes
1answer
93 views

Limiting the current without limiting the voltage

I want to design a current limiter, for both negative and positive voltages, for my thesis project. My design consists of a voltage source (+/-10V)(X5) and a transimpedance amplifier(X1.) Using the ...
0
votes
2answers
70 views

Current limiting range on LM723 (from 0 to 5A)

I am building a power supply with LM723 and my intention is to have 0-30V and a range of 0-5A variable. I am regulating voltage normally, however for current limiting, if I want to regulate small ...
-1
votes
1answer
58 views

Help/guide to design over 1 mA current circuit with 5000 Vrms and 150°C operating conditions [closed]

I am designing an over 1 mA current detector circuit using IN193 with a supply voltage of 5000 Vrms to the test sample IC at 150°C temperature as shown in the attached figure. I expect that circuit is ...
0
votes
1answer
97 views

How to modify TL431 current limiter to work with 80V bus?

I referred following circuit from TL431 datasheet TL431 max voltage at cathode is 36V. since circuit has only a transistor , how to modify this circuit to work with 80V at input(Vi bat). output ...
3
votes
2answers
326 views

Custom 25 A mains inrush current limiter design review

I've designed an inrush current limiting circuit and would welcome a review from experts with more experience with this sort of thing. The load will be around 50 x 19 VDC @ 3.5 A linear power supplies ...
0
votes
2answers
69 views

Voltage in a circuit with variable resistance and diode in series?

I came across some examples to calculate the current in a circuit with diode and resistance in series. Consider the circuit below: Current was calculated as follows: I = (9 - 0.7)/R1 Does that mean ...
0
votes
1answer
81 views

Value of resistor to limit current to 1 ampere in 12 volts circuit

I want to connect my modem directly to a 12volt battery so that I dont need a adapter. My modem’s specs says that it need 12 volt 1 ampere as input.Now the voltage of 12 volts can be directly given by ...
0
votes
1answer
60 views

Current limiter problem

I am designing the following circuit to limit current inrush to a device on startup (to about 1.5 amps over about 3 seconds). Rload is just for testing, the actual load is a bunch caps at 56v, but I ...
2
votes
2answers
122 views

LED fairy lights with series capacitor?

I've opened up the battery box of a string of fairy lights (like pictured at bottom) and found a resistor, plus what looks like a capacitor in series with the lights. Is this really a capacitor? If so,...
0
votes
0answers
47 views

How to split high current low voltage? Voltage regulators , current regulators(?)

I am using a 20v dc laptop charger that supplies 4 amps. I need 5v dc 4 amps. When I use a linear voltage regulator it’s too much current to pass through safely.. 15 amps change and 4 amps, so I use a ...
1
vote
0answers
36 views

JFET Constant Current Source (CRD alternative)

Today I have build constant current source based on J111. To drain I connected VCC it's 24VDC from laboratory power supply, then I connected resitor 470Ohm between gate and source. To source pin i ...
0
votes
0answers
25 views

LED circiuit for a current limited circuit

I have the following requirements for a circuit: The circuit is supplied from a 500mA current limited voltage source The circuit should indicate the status of the supply, i.e. if it is in current ...
4
votes
1answer
70 views

Get the max current through relay without activating it

I have a circuit where the only current I can get to supply my battery is the one that I can get from a relay connected to Vcc. When it is not pulled to GND I can get current without activating it up ...
0
votes
1answer
42 views

Limiting the current with the LM2679

I'm building a power supply, and I'm trying to see if the LM2679 will fit my needs. I like how it's similar to the LM2596 as well as the fact that it has a pin to limit the switch current. However, I ...
1
vote
0answers
124 views

24V battery charger with LM723

I have a 28V steady DC input, and I want to use it to charge 2x12V lead-acid batteries in series. I want to use the LM723 IC to make an adjustable (26V to 28V) regulated output, as it has current ...
0
votes
1answer
45 views

What will gain be when both the zener diodes are conducting?

I have seen in solution that they have considered both 10k and 20k to be parallel when both the diodes are conducting. How will 10k and 20k be in parallel when zener diodes are conducting? Why are we ...

1
2 3 4 5
10