Since all circuits have current adding this tag is rarely appropriate. Flow of electric charge - typically movement of charge carriers, such as electrons. Measured in amperes (A).
0
votes
1answer
88 views
Effect of an isolation transformer on leakage current
How do isolation transformers affect the leakage current through protective earth in a system?
Scenario 1: Mains is directly connected to circuit. Metal enclosure has a protective earth connection ...
0
votes
2answers
35 views
NCP59302 resistor question
What resistors do I need to get 5V on this chip? Sorry, I don't understand the reference to the Iadj in the formula. The section on the Iadj in Adjustable Voltage Design seems circular.
...
4
votes
1answer
106 views
How to build a voltage-controlled current sink / voltage-controlled resistor
I am trying to control a current through several current-mirror device (specifically the IREF pin on the TLC5940) using a single potentiometer. I've tried using a ...
3
votes
1answer
76 views
What do I need to know about leakage current?
I recently suggested a plan of removing one end of a resistor from a breadboard to remove it from the circuit in order to measure its resistance, but my mentor suggested that this won't work for high ...
1
vote
2answers
66 views
simple h-bridge polarity reversal
I am trying to reverse the polarity on a rather beefy motor (5 amp, 60v) in the most simple way possible.
I need to build an h-bridge just to reverse the current, I am controlling speed elsewhere. ...
3
votes
1answer
50 views
Convert between dBA, dBV and RMS values
How do I convert between dBA, dBV and RMS values? For example, I have used a current probe (clamp) with a gain of 100mV = 1A to measure a series of currents in dB and I would like to know the ...
1
vote
1answer
41 views
what is the effect of a current-carrying wire through a solenoid?
The solenoid coil concentrates the magnetic field lines through the interior when the solenoid wire carries a current.
I am curious about a different case, however. If a (separate) straight wire went ...
1
vote
2answers
34 views
IGBT's Ic (peak current): why always 2 times of Ic
I would like to know:
1) Why, almost on every IGBT datasheet that \$I_{cm}\$ (maximum peak current) is 2 times \$I_c\$? - for example see datasheet
How, can I measure this \$I_{cm}\$, to verify that ...
0
votes
1answer
81 views
Current flows from the source towards the sink
I happened upon the following schematic:
simulate this circuit – Schematic created using CircuitLab
It's supposed to reduce the max.voltage between the GPIO input pin and the current ...
0
votes
1answer
54 views
Low voltage/current power supply for wide range of inputs
I was thinking of simple low voltage/current power supply that can accept wide range of input voltages, up to the hundreds. Let's say, the input is 20 to 160V DC and output has to be 10V with 20ma ...
2
votes
1answer
67 views
transistor loop to limit the current
I am trying to implement the DALI TX/RX circuit below.
The description says:
The other transistor (T2) is controlled by the current flowing through the
resistor (R1). If a DALI slave unit is ...
-3
votes
0answers
40 views
How long does my battery last? [closed]
The only information I'm given is that each battery has a useful energy of 100000 Wh (500 Wh/kg), my discharge rate is 10C, and has to power an electric motor that should output 1000 kW. I'm having ...
2
votes
1answer
64 views
Octopus Component Tester Analysis
I'm a beginner in electronics and my knowledge is pretty basic. I've been trying to understand how the Octopus Component Tester Works. I know that it's outputs should be used to plot a Current x ...
1
vote
1answer
70 views
connection from an comparator to an optocoupler
I have the circuit below to decode a signal that is defined as Logic high >9.5 V and Logic low <6 V
To determine the ...
0
votes
2answers
127 views
DC-DC Voltage Doubler
I am an amateur, but i'd like to know if this circuit would work to double a 0-30 volt DC input to a 2-60 volt DC output. If so, what kind of CAPS and DIODES do i need to support this? I need to Power ...
1
vote
1answer
93 views
how to control constant current led driver output with pwm?
i want to control brightness of led series with constant current power supply.
but when i connect the power supply output to pwm controller and led series, i cant control the brightness because power ...
0
votes
1answer
79 views
How does a multimeter convert voltage/current to a numerical value?
Just wondering... How does a digital multimeter work ? How can it convert a voltage, a current or a resistance to a numerical value ? I guess there is some programmable chip inside, but how does this ...
6
votes
3answers
339 views
Why can't a power supply supply low current?
I've just read this article and don't quite understand how a power supply can't supply such a low current. I was always under the impression a power supply could supply anything up to its rating, but ...
1
vote
3answers
87 views
Measure current on a constant current source
I need to measure current on a constant current source(LM317), because I am using a 3v3 chip I also need a voltage divider to read it. Will this circuit work Or will it wreak havoc trying to increase ...
3
votes
1answer
138 views
Higher current LED driver for persistence of vision display
Project needs
We need an inexpensive LED driver IC that:
Can source or sink at least 15mA/LED
Has an SPI-like interface (not I2C)
Has a separate latch pin
Has at least 256 grayscale intensities
...
2
votes
2answers
88 views
What is the capacitor charging time when charged with a pnp current mirror circuit?
I want to use a 555 in monostable mode to make a ramp signal generator. The capacitor would be charged using a current mirror circuit.
Given a input voltage, what would be the charging time of ...
3
votes
3answers
340 views
220V 0.2A converted to 12V 5A, where are the missing amperes?
I have an AC adapter at home that reads (roughly) the following:
uses 220-240v AC 50Hz at 0.2A
produces 12V DC at 5A
I'm a little surprised that it uses 0.2 amps and produces upto 5. Here's what ...
5
votes
1answer
174 views
How does this LED setup work?
I noticed this LED setup in a datasheet for the Kingbright SA40-19EWA. Instead of the leds being in a simple series or parallel setup, each segment of the display has four sets of two leds in ...
1
vote
1answer
54 views
Cable thickness for solar borehole pump
I have a solar borehole pump: 24 volts - 270 watts panels (two x 135W). I want to move my panels 300 to 350 meters away from the borehole, reducing the risk of theft. What size of cable should I use ...
1
vote
1answer
66 views
Why does the nichrome heat up?
If I have a copper wire and a nichrome wire of the same gauge (e.g. 30 awg) with the same current passing through them. why does the nichrome heat up significantly.
Also, the length of the wires are ...
0
votes
1answer
60 views
How does the maximum current of solar cells combine in series?
Say I have one 4W PV cell and one 2W PV cell (both producing about .5V). I know enough to say that maximum current of the first cell is 8A (4 / .5) and the maximum current of the second cell is 4A (2 ...
3
votes
2answers
148 views
Vacuum cleaner power rating does not match line voltage and current rating
I have a vacuum cleaner on which is proudly written:
12.0 Amps
1300 W
Assuming a 120 V (RMS) power supply, how would the power consumption of the vacuum cleaner be calculated given the 12.0 ...
-2
votes
0answers
41 views
can we consider that in the forward -bias ,the diode become short circuit ?? and the opposite with reverse bias? [closed]
A lot of current flows when the diode is forward-biased, provided that the voltage is higher than 0.6V or so for a silicon diode or 0.3V or so for a germanium device. A very small amount of current ...
3
votes
2answers
122 views
arduino pulse to transistor power maximum
Hello I want to get a confirmation that what I am doing is not going to fry my Arduino Mega.
The sketch I am using to send a pulse out on pin 8 to a 2n3055 that is switching 12 volts is this:
...
-4
votes
1answer
73 views
DC Current Regulator 24v [closed]
I am trying to connect solar panels to a battery and then add a grid tie inverter of 1 kW. If you connect the grid tie inverter directly to the battery it draws way too much current, gets too hot and ...
1
vote
2answers
136 views
Problems when sharing a battery between motors and radio in an RC car
Background
I am building an RC Car that I am trying to modify to control from an Android phone.
When I connect the remote control module as well as the car circuitry (servo & motor) to separate ...
0
votes
4answers
112 views
How input current affects circuit? Is it ignored?
All the examples I have seen so far, take the input voltage as-is and start calculating circuit current depending on on-board resistors using ohm's law etc.
Can you just ignore the original current ...
2
votes
2answers
52 views
Input impedance of Arduino Uno analog pins?
I'm using the ACS712 hall-effect based current sensing chip on some small robotic arm motors, and reading in the analog voltage with an Arduino Uno. I've had reasonably good results, but only after ...
4
votes
4answers
165 views
Can electronics be damaged by under-currenting it?
Someone just asked Can electronics be damaged by undervolting it?, so now I am going to ask under-current. Let's say something requires 10A, 12V, if I limit the current to 5A, could anything go wrong?
...
2
votes
1answer
58 views
Frequency Scaling and current draw
I am trying to power a RPi of 4 AA's, and my mobile power device can only output limited current (500mA), but I can underpower my RPi by frequency scaling. Is frequency scaling and current draw a ...
0
votes
1answer
54 views
DC-DC converter maximum current rating
I am using an XP Power XP-IL1224S 12V to 24V DC-DC converter, does anyone have experience with the current rating of these kinds of parts?
The maximum current is rated as 84mA @ 24V, which works out ...
0
votes
1answer
87 views
Ground Fault Question Regarding a 3 Phase Circuit
I'm needing to design a 3 phase ground fault detection system for a 480V system. It will need to be able to trip when there's ground fault current >1A.
I have done some reading and it sounds like ...
-4
votes
1answer
113 views
How to find the current and Resistance?
Ok Everyone DownVoted! i am sorry about the diagram! So i Updated it
this is my new diagram:
simulate this circuit – Schematic created using CircuitLab
Then Now how to find I1? what is ...
2
votes
2answers
103 views
Can a too powerful battery damage a circuit? [duplicate]
I have an IOIO board, a 13V 10A Battery (when I tested with my multimeter). For the IOIO board, 5-15V, ~10mA is enough. Can a 13V 10A Battery do wrong to the board or is it okay?
3
votes
2answers
109 views
Ground vias on high speed PCBs
I know that if I use vias on high speed traces that I need to reduce the inductance effect of the via. So I will put ground vias next to these vias to help returning current. I have seen a picture ...
1
vote
1answer
52 views
Detecting Motor Overload
I want to make a circuit to indicate an LED if a motor is drawing too much current. (when the motor is stopped for example mud got stuck around the gears) I am using 9-12 volts to power my motor, and ...
2
votes
1answer
130 views
Calculating current in a simple circuit
I am new to electronics and am trying to figure something out:
I have a source putting out 12.6V and an unknown current.
I know that I can calculate current by finding the voltage drop over a ...
9
votes
3answers
143 views
Current produced by thermocouples
I can't seem to find an answer to this on Google.
Take a K-type thermocouple for example. The voltage produced is around 41uV/K. I'm wondering how this changes when a load is put across it. What ...
2
votes
3answers
171 views
Circuit that can convert current pulses to voltage
I have an anemometer which outputs current pulses. I can't take it apart but I know there is a phototransistor and LED in parallel shining through holes to it. I was told that with 30m/s wind there ...
2
votes
1answer
156 views
current controlled current source
Objective
I am trying to build a gain-of-1 current controlled current source (current mirror) that is less sensitive to resistor value variation. The designs i have been making are highly resister ...
2
votes
2answers
75 views
Measuring the current of a DC circuit
I'm creating a set of modules that can be daisy chained and hooked up to a master controller unit. I'd like to have a display on the master that shows the combined current draw of the modules in ...
1
vote
1answer
47 views
Values in a solar array
My dad had just bought a solar array of 4kW together with an inverter, a kaco powador 4400.
The array is now running and generating electricity. I am trying to understand how it all works, but ...
1
vote
0answers
74 views
Why does my bluetooth dongle use more current when paired then when idle?
I have a bluetooth dongle which is connected through USB to my PC. I wanted to measure the current drawn and hence I connected an ammeter in series with the 5V line and am measuring the current. I ...
1
vote
1answer
121 views
Amperian loop to measure solenoid's magnetic field
My textbook proves the formula \$B =\mu_0In \$ for a solenoid by taking a rectangular Amperian loop as shown here:
The problem I see with this though is that it only takes into account the ...
4
votes
4answers
270 views
Is current the same coming out of an IC as it was going in?
This is my first diagram so keep that in mind. I've come up with this circuit because
I've got some 74** series ICs and I want to be able to make them work. This example is
a simple AND gate with ...
