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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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63 views

Raspberry PI Zero - 5VDC output current?

I was planing on using a Raspberry PI Zero W for å smart lamp project with WS2812b LEDs, to avoid separate power supply for the LEDs, my plan was to power the LEDs from +5VDC on the RPI ZW. The lamp ...
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52 views

What to consider when powering multiple devices in parallel?

Briefly about my background, which might inform the question. I'm currently self-educating myself on some electrical engineering on-the-job. I'm learning from Art of Electronics and some other ...
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68 views

DIY toroidal transformer spot welder

I've put together a toroidal transformer using a core suitable for 1500VA. The primary coil is around 70 turns with the secondary coil being just one. When I plug it into the mains (110VAC), I just ...
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719 views

Why are these LED current limiting resistors so big?

I'm looking at the charging circuit for a lithium ion battery that was made by Adafruit. Here's an excerpt: If there's a 5V rail from the USB port and a 470 Ohms resistor, is that limiting the ...
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128 views

Microwave oven: How can I temporarily limit the startup load?

Problem: It's a common problem for "NON-inverter" type microwave ovens to pop circuit breakers, and mine is no exception. There could be a huge number of reasons for this. Even though I thought I ...
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68 views

Current limiting a starter motor

I'm planning to try to build an electric go-kart. My idea was to use a 12V starter motor from a car to power it, since used ones are fairly cheap and easy to get. (I already have 2 of them to ...
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70 views

270v DC current limiting circuit

I have looked through some of the current limiting responses, but don’t see any close to what I’m working on for my project. I have an EV system running in around 200 - 270V DC. I want to build a ...
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562 views

Digital Current limiting with MCU

All current limiting circuits I've found until now use some sort of analog Logic with Op-Amps to limit/control the current. (Why) is no digital current limiting used? I would imagine a shunt resistor ...
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62 views

Does this neon indicator light require a resistor to limit current?

I've got a few of these indicator lights from LEECRAFT/VCC, they're marked "tineon 3600" and "125V 1/3W". According to this page: http://wiki.diyfaq.org.uk/index.php/Neon neon lamps require a resistor ...
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51 views

Adjustable voltage source 10 – 50 V and adjustable current limiter 2 – 70 mA

I would like to build a source that gives on the output an adjustable voltage from 10 V to 50 V and that current be limited from 2 mA to 70 mA or make some circuit that let me choose 2 mA, 1 0mA, 50 ...
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66 views

Is my understanding of this level shifter correct

I am considering using this TI LSF0102 level shifter in my circuit - but would like to understand, based upon its datasheet, if I have my understanding correct. It says it has a 100mA current rating, ...
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TPS562208DDCT current problem

I have attached a PSU design which I have created. The input voltage is between 12 and 24V DC. The first stage creates an isolated output voltage of 7V that is then fed into the two TPS562208DDCT (...
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24 views

IT characteristic implementation of motor protection circuit

I am trying to implement The IT - characteristic feature for motor protection device.There are 2C,5C,10C curve feature . can someone suggest me how it can be implemented in C code. Is there any ...
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64 views

Calculating value of a current limiting resistor in a constant current circuit?

I am using 12 leds in series with 3.0-3.4 v forward voltage and 400-500mA forward current (these values are from the datasheet). I am using a constant current led driver(24-40v and 580mA). My problem ...
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88 views

Current limiter using pnp transistor

I have below design and want to know it is correct or need to change anything. Details are as below Input voltage is from 18V to 40V and can draw only 2mA current from source voltage. so I have ...
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Inrush current limiter circuit for filament bulb - comparison

Context: A 12V power supply is switching on externally connected 12V filament bulbs. The power supply's load switch implements an electronic resetable fuse (13A/τ=15ms) in case of an external short. ...
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86 views

What's inside this current limiter?

This component was inside an isolation transformer. It's obviously for limiting inrush current, but how does it work and what is inside? I believe it's a relay of some sort, switching a resistor in ...
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57 views

Current limiting source using opamp

I wanted to know if I'm correctly thinking. The idea for current limiting is to force the opamp to output the correct voltage to control the MOSFET. So the maximum voltage possible is somewhere ...
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66 views

Surge or other suppressor I can use, to prevent tool blowing fuse if blade sticks [closed]

I want to say up front, that this question involves minor modification (transient surge/current suppression) to the power supply side of a power tool. Usually I'd be the last to do anything like this (...
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1answer
71 views

active current protection with diode instead of shunt resistor

Is this current protection technique going to work? I came up with this because I want to make a current protection circuit and I do not have a shunt resistor at hand. I think the circuit should work ...
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1answer
216 views

Limiting current to 20A with 48V in

I'm an electronics newbie and I need some help/advice with a project. So basically I need to make a sort of programmable power supply module (or at least that's what I think I gotta do). I got a DC ...
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2answers
94 views

Resistor or no resistor between this IC and the pmos GATE?

I'm using this IC (https://www2.mouser.com/datasheet/2/609/ADM1270-878589.pdf). This IC controls the GATE of a pmos. I'm thinking about using this MOSFET (https://www2.mouser.com/datasheet/2/389/...
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2answers
103 views

Laser Diode Feeding

Edit: Laser diode info page I have a basic question about laser diodes. For a 14-pin butterfly package as shown below. I know that I need to control the current going in to the laser diode, but I don'...
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1answer
107 views

Op amp current regulator

This is probably a marginal mistake. This circuit, a current regulator: simulate this circuit – Schematic created using CircuitLab Works fine on simulation. However, it does not once built. ...
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2answers
177 views

How to limit HV capacitor charging current?

I have a voltage doubler, which is connected to mains (without galvanic isolation): It enticed me with its simplicity, configurability and option between charging speed or desulfatability. The ...
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3answers
99 views

I2C device lists 20mA max current on AD, CL, and DA pins. Do I need a resistor between it and Arduino?

I'm looking at the datasheet for an LED controller (the MAX6955), and it shows that all of the interface pins; clock, data, address, etc., have current maxima of either 20 or 40mA. I'm aware that the ...
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146 views

Overcurrent Sensing

I am designing an overcurrent protection circuit. I am sensing current with a LEM sensor across a sensing resistor of 16.5 ohm. The voltage drop for maximum current is 2 V. In the next stage I am ...
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1answer
214 views

Current limiting ballast for a transformer

So, guys, I hope you can explain to me how to calculate the necessary parameters for a ballast to limit the current on the primary side of a high voltage transformer.It is for a tesla coil project. To ...
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1answer
250 views

MOSFET as inrush current limiter (passthrough parasitic C?)

I have a circuit based on a P-FET which shall limit inrush current (20 mA). However, when turning on the power supply there is always a current peak (30 mA, 5 ms) through the M1. Even if I tie its ...
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43 views

Sharing a 5v Supply

I want to deploy a Pi Zero in a weatherproof box. I need to provide 5v DC for the Pi and an 8 channel Relay Board and two 5v DC pumps. I have a 5VDC 5A 25W single output power supply that seems ...
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1answer
23 views

Lower maximum current rating on available motor driver .

I am designing an arduino controlled autonomous bot with 2 DC motors to control. The motors i have to use are 500rpm 12V Johnson DC motors with Torque : 8kgcm and No-load current = 800 mA(Max), Load ...
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2answers
314 views

Mosfet heating in current limiter circuit

I am designing a lead acid battery charger using Battery University for guidance. This is the circuit I made. The power supply is from an Adjustable 12V power supply. I have set it to 14.4V. The ...
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27 views

Controlling two DC brushed motors, 12V and 2.4V, limiting current while also supplying logic circuit

I have a system which is going to employ two DC brushed motors. The main power supply supplies 12V and is rated for 3A. I'm attempting to maximize the available current to each motor. The smaller of ...
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62 views

Why does the high Side Current Shunt monitor fault as soon as power is on

The high side current shunt monitor fault goes high as soon as power is turned on preventing the P-MOSFET from turning on, its not faulting because of over current but as soon as the Enable signal ...
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101 views

Laser Diode Driver and Cooling

I am a newbie at analog design, and trying to design a laser diode driving circuit and TEC cooling circuit for a 14 pin laser diode, such as P1550-ADF-B: 1550NM ADF LASER DIODE which has forward ...
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3answers
96 views

Series inductor to limit motor current?

Short question: Would it be possible to use a series inductor to limit the inrush current when switching on (or briefly loading) a DC motor? Longer question: I have a battery-powered motorized toy ...
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2answers
70 views

High power LED array

I’m designing SLA 3D printer and I need to design UV LED array for LCD screen backlight. Preliminary design is 5x3 (5 parallel lines with three LEDs in each). All LEDs will be soldered on PCB. The ...
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4answers
97 views

Controlling the power through a heating element?

I need a 25mm x 30mm 120V 200 watt band heater. Unfortunately, the only 25mm x 30mm 120V band heaters I have found are 300 watt. What sort of circuit could I construct or purchase that could ...
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1answer
503 views

4 channel optocoupler [duplicate]

I was designing a dual H bridge board which uses some logic signals to drive 8 mosfets. Initially I was using 8 optocouplers per board which was really annoying to wire up. after a bit of searching, I ...
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1answer
346 views

Using mosfet as diode (Making an UPS)

I'm trying to make a high power UPS, I have a 13.6V PSU and an Inverter and a Lead acid battery. Everything would be connected this way: There's a problem with that circuit, if the battery is too ...
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2answers
1k views

Advice about microsd current consumption [closed]

I'm designing circuit with STM32L0 MCU that storage some data in microSD via SPI interface. I have power budget of 5V @ 500mA via VBUS so, I would like to estimate microsd's current consumption. I ...
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1answer
65 views

how to understand the permissible voltage and current of film capacitor?

I use the 0.12uF metallized polyester film capacitor Model ECQE2124JB which has 250VDC rated voltage. I have a sine wave across the capacitor, then can I think that the maximum AC voltage is 250/1....
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1answer
48 views

How to limit current on parallel outputs from a power supply?

So I am trying to make a USB power dock for multiple devices. I have a 5v 20A power supply. If I connect 10 USB ports in parallel, is there a way to cap their current to 5v 2A? I don't want to fry my ...
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2answers
72 views

how many amps would a 12 v -20 ahr battery draw when charged with unlimited current power supply?

i have 3 X 12V battery i use them to drive a dirt bike .i want to charge them with a 36v-30A power supply the maximum charge current is 6 amps that is given by the manufacturer . will this damage my ...
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3answers
244 views

Current limiting resistor on peltier element

I have a 12v/22A DC switching power supply and 9 peltier elements rated for 12v/6A. I would like to limit current to 2A per peltier element. I don't know how to calculate the impedance (in ohms) ...
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1answer
91 views

Old laptop power brick > DIY current regulator > 20w COB LED - will it do what I think it will? [closed]

I have a salvaged 20W battery-powered work light: the housing and LED inside. Before the electronics and the original 7.4v dead battery got tossed, I hooked up a somewhat discharged 7.4v battery to it ...
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67 views

How to limit starting current of a SEPIC based LED driver?

I have designed a SEPIC based LED driver which gives 60 V, 350 mA constant output with a good power factor. It is connected with 220 V AC source.Then I have used full-wave rectifier.After ...
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2answers
171 views

How to calculate this current limit circuit?

How to calculate this current limit circuit This is a current limit, can anybody give me some instructions about how to calculate the limited current? My calculation is as follows: (V1-0.51*I)*33/(...
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0answers
84 views

Theory of Operation for Arc Lamp

I am attempting to power an arc lamp (which I have) using a programmable power supply (which I have yet to source.) Though the lamp is rated at 1000w (37v at 27A) I would like to power it at about ...
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63 views

Output impedance function generator, limiting the current

I've the following schematic: simulate this circuit – Schematic created using CircuitLab Now the R of 50 ohm does limit the current that be supplied to the load. Is there a way to be ...