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Questions tagged [current]

Flow of electric charge - typically movement of charge carriers, such as electrons. Measured in amperes (A).

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60 views

Why is my RGB not drawing more current?

I've got a 3-9W RGB LED (https://www.adafruit.com/product/2524). It's connected to a breadboard with a power supply that tests as giving 4.9V and 2A on a short circuit. I've got 5W resistors at ...
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0answers
60 views

About device in which potential drops in direction opposite to current [on hold]

A small intro: We have mainly three types of electronic-devices with their characteristic property: Resistor with Resistance(\$R\$) Capacitor with Inverse of Capacitance(\$1 \over C\$) ...
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1answer
45 views

Reverse Current leak Battery+Diode in parallel

on my design, I am using two coin batteries in parallel and each battery has a Schottky diode in series to block the reverse current, in theory, it will avoid the higher potential battery "charge" the ...
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1answer
32 views

Minimal circuit for a current limiter for small dc voltages and low power

I remember to be able to build a current limiter for small dc voltages around ttl levels using a zenner diode, transistor and resistor and some math. I couldn't find one when browsing, how do I build ...
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1answer
24 views

Average Current for switched circuit

I'm looking to confirm I have the correct process to determine an average current for the following switched circuit: I peak is given as 10A I rms is given as 1.8 A. From: $$Irms = Ipk\sqrt{D}$$ I get ...
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0answers
32 views

Current source output

What can I do to eliminate the output voltage when there is no load on my circuit, even if there is any level on V2? I have do develop a current source that doesn't provide output when no load. Thanks
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1answer
30 views

Function generator output

A function generator is hooked up to two resistors in series. The voltage across the function generator changes over time, shown by the different graphs The questions asks to find the output voltage ...
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2answers
53 views

What happens if LEDs do not get enough current? [duplicate]

I'm building a lighting fixture using big led panels. The LED panel says it requires 7 amps @ 12 volts, but the power supply I have is only rated to 4 amps @12 volts. What will happen? Will it ...
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1answer
226 views

Parallel Power Supplies with Ideal Diodes

I'm working on a project that operates at 5v - and can draw UP to 10 amps. Under normal conditions, it won't be doing that - probably closer to 3 amps, and (if configured for low-power) only 450mA or ...
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1answer
45 views

Can I use network cable for low voltage DC power?

I'm a guitar player with a crazy idea for a 2 part bypass looper: Enclosure A is just big enough to house 4 footswitches and an ethernet jack. Enclosure B has 9V DPDT relays to route audio ins and ...
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0answers
65 views

Why the opposite of the passive sign convention is not the active sign convention?

Studying the fundamentals of circuit theory, I was reading the Wikipedia article on the Passive Sign Convention and found out about the Active Sign Convention (ASC). After searching many introductory ...
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1answer
52 views

Measuring integrated current

I want to measure the amount of light striking a photodiode in a specific time window (about 1ms). In this window, we get \$10^6-10^7\$ photons, which get converted into electrons with about 80% ...
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1answer
64 views

Problem with high current draw in circuit design

I am working on a project where I've taken an LDC1612evm (inductance to digital converter) and removed the connected micro controller portion to communicate with a TM4C123G LaunchPad via I2C. I have ...
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0answers
47 views

Voltage law not correct [closed]

Is the voltage wrong? Across the resistor there cant be any voltage drop because the electric field of a battery that forces the electrons to move is constant for all points inside the conductor.Just ...
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1answer
42 views

Does a common neutral between solar inverter and utility affect current measurement?

I have solar hybrid inverter at home that's connected to the mains using both, the line and neutral wires. However, to save the costs, I've connected the load to it using a common neutral i.e. I've ...
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0answers
28 views

Current Source Output Stage

I'm developing a current source based on NPN Wilson modified current mirror. There's a restriction that cannot be used opamps, so i'm using only transistors. However, it's fundamental that doesn't ...
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1answer
54 views

Variable Constant Current Supply

I've been looking around for a good CCS schematic, and decided to try making a simpler one even if it means it'll behave worse. I need a 12V (would come from an ATX power supply, more than enough ...
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2answers
49 views

Current Rating of a device (how does this change when changing the voltage)

Let's say you have a device that is rated at the following: 550 amps @ 12Vdc (heat) Max Voltage = 48Vdc (insulation material max voltage rating) I am mainly concerned with the heat, we could ...
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1answer
67 views

Random values of voltage near ADC in current loop

I have implemented a circuit which allows to isolate a current-loop-based sensors. The schematic is as follows: Everything seemed to work good in the breadboard. Without a MAX14626 IC, the circuit ...
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3answers
218 views

Potential difference and current flow

I've been taught that electrons move from cathode to the anode (negative and positive). But what happens when I apply positive voltages at +10V at one end of the circuit and +6V at the other? How ...
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2answers
37 views

How much current does the Eltako ER12-001 need to switch the output?

The Eltako ER12-001 seems to be an interesting relay. It has an integrated electronic circuit to operate a bistable relay, while acting like a normal one. The control current can be either AC or DC, ...
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2answers
56 views

Charging capacitor to power LED with a low current source

I have a 10000uF 6.3V capacitor, and my source is generating 3.3V and 15uA of current. How long will it take to charge it enough so i can pulse a standard 5mm LED for lets say 1 second?.
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2answers
71 views

Does connecting LEDs in parallel use more current then connecting them in series in my circuit?

Sorry if this is a dumb question, I need a sanity check on this stuff. Is it possible to give LEDs varying current, without sacrificing efficiency? Basically I have 4 LEDs which could all use ...
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1answer
73 views

Kirchhoff's laws circuit, How to calculate unknown resistor?

First time here! I got a question on a test that I cant get my head around. How do I calculate value of R2 ? Is it possible ? Thanks in advance !
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1answer
63 views

Why electrical appliances flicker and dims is it because of current drop, voltage drop or power drop? [closed]

In my house in India , suddenly one day night the lights flickered and turned dim I wonder is it because of current drop, voltage drop or power drop ?
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3answers
73 views

About dynamic equations and the transfer function for the circuit

/ Attempt Follow my setup $$v_1=u_2$$ $$i_1=C\frac{du_2}{dt},v_2=L\frac{di_2}{dt},i_2=\frac{u_2-v2}{R_2},i=\frac{u1-u_2}{R_1}$$ According to KCL: \$i=i_1+i_2\$ Let \$s=\frac{d}{dt}\$ Get \$R_2(...
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1answer
40 views

Harvest energy from ultra low current and high voltage source?

I have a sensor which can produce voltage upto 10 V but can only produce 50 nA of current. I tried to harvest energy using TI's BQ25570 evaluation board but the current is too low to kickstart the ...
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6answers
103 views

Optocoupler Characteristics

In my application I need to isolate a PWM signal @ 1 kHz, which is generated from a Beaglebone Black microcontroller. In my signal, I want to have one hundred different steps in duty cycle (from 1% to ...
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1answer
31 views

Definition of \$ \frac{mm}{Ampere}\$ (unit of current sensitivity)?

I want to know how \$ \frac{mm}{Ampere}\$ (which is the unit of current sensitivity of PMMC instruments) is defined? i.e, How \$ mm \$ is defined in terms of \$ degrees\$ ? For eg.: \$ \frac{rad}{...
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0answers
20 views

Amperage rating of electrical panel [migrated]

Replacing a sewage pump for a building Existing panel is Challenger Electric J94 Company discontinued so unable to find amperage I know the Voltage-Motor Horsepower rating information. What is the ...
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2answers
34 views

How to read this figure (UDN2981 max current)?

This question is related to this question: why-are-the-pins-of-an-udn2981-related? In the UDN2981 datasheet, the figure below shows the maximum current (page 14, bottom left picture). Does this ...
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2answers
28 views

Why are the pins of an UDN2981 related?

This question is related to this question: udn2981-maximum-output-current-too-less. In the UDN2981 datasheet, the picture below shows the maximum current (page 14, bottom left picture). Since if I ...
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3answers
93 views

Why is the output frequency of the zero crossing detector (square wave generator) double that of the input signal?

I have built a zero crossing detector that acts as a square wave generator according to the circuit diagram shown. It is connected to a potential transformer. The output from the potential ...
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0answers
34 views

Partial power outage ,facing single-phasing [migrated]

My short name:Teza, we have had partial power outage in our house since months ago. First we would hear a short chirp sound then we would see flickering of some light bulbs, then power would go out, ...
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0answers
69 views

How to distribuite high current in multilayer PCBs

I'm designing a 150Amp controlled rectifier and I'd like to know how to distribute the current using a multilayer design. Currently, I have a 4 layer design containing: Top Layer: 6oz, Vdc+ and Vdc-...
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0answers
20 views

Uncertainty in current values of Power HD digital servo motor

In a project, we want to lift the load of 5 kg on the ground to half a meter. For this purpose, we use a 360-degree rotating PowerHD digital servo motor with a stall torque of 20 kg / cm. Motor ...
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0answers
49 views

UDN2981 maximum output current too less

For a LED 'matrix kind of' project I want to use UDN2981's for sourcing, and ULN2803's for sinking. I want to use 5mm LEDs, being able to use 100 mA (10% duty cycle). Since the ULN2803 can handle ...
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3answers
855 views

In which way proportional valves are controlled solely by current?

Proportional valves are drived by current because we need a steady force and since resistance changes with temperature if they were driven by voltage this force wouldn't be steady. Ok, this is what I ...
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2answers
108 views

Why (physically) does a current divider circuit show that both resistors have an effect on individual current?

I understand both the current divider formula and why it is mathematically correct. I am curious though why physically this is true. My book provided me the following circuit: simulate this circuit &...
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0answers
54 views

Current splitting in nA,pA range till 100 kHz frequencies

This relates to my previous question of current splitting. Current splitter/divider in nA/pA range possibilities I read about some circuits on current copying (current conveyor). However, the ...
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1answer
96 views

Current splitter/divider in nA/pA range possibilities

My objective is to realize a current splitter which could split current from a wire A in the range of pA, nA equally to wire B,C. I was initially sure what this type of circuit would be called, but ...
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2answers
41 views

How to choose proper power supply for 8 servos on Adafruit shield with Arduino Uno controller

I use Adruino Uno micro-controller powered with USB 5V from PC and Adafruit 16-Channel 12-bit PWM/Servo Shield on it with 1000uF capacitor, powered with 6V 2A power supply. Seems like it is not ...
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1answer
63 views

Crude Li-Po Battery Charging. Is it safe?

So I have this drone and I want to play with it but there are no chargers for it nor are there cables for this kind of li-po here but I have minimal knowledge with electronics, just enough to make ...
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2answers
71 views

Figuring out the principal working of constant current source

I've the following circuit: simulate this circuit – Schematic created using CircuitLab I was told that this is a constant current source. I think that the resistors \$\text{R}_1\$ and \$\text{...
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1answer
54 views

Why does not all the current flows through Zener diode?

Let's assume the following circuit, where Zener diode is used as a voltage regulator. R16 (R18 later) is the load. When the input voltage is sufficiently high for Zener diode to be reverse-biased, ...
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1answer
71 views

How to find Ron

Compute the effective Ron in the triode region of the v-i characteristic when Vgs = 3V, i.e., measure the current through the MOSFET switch when, say, Vds = 1V and report Ids/Vds as your answer below. ...
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1answer
62 views

Power Transformer question to power a motor load

So I bought a toroidal power transformer that can output 117Vac, 12.8A and has a power rating of 1.5kVA in order to power a motor that requires 115Vac, 13A. I wanted to see if this would be viable to ...
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0answers
75 views

Trapezoidal Rule of Complex RLC Circuit using MATLAB

I am having difficulty trying to figure out how to solve this circuit using the trapezoidal rule. I know how to do so in a first and second order RLC circuit however this particular circuit is giving ...
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0answers
180 views

Make a constant current source using a 700VDC supply at 4A

Goal: Charging a capacitor to 700V I want to charge a capacitor(any value) to 700V using an SMPS (buck converter.) to prevend inrush current. It's important that the system could charge the ...
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0answers
25 views

Labview - Active amplifier

I need to create a pulsed current variable from 0 to 20A to run solenoid with a very low resistance. Which is the best solution for you? Right now I am trying to generate a pulsed current with ...