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
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4answers
130 views
How to get high current from 9 volt batteries
I am planning to make a solenoid.. Which should be so powerful as to lift up about 600N force.
I have thought about it, and I have a doubt. How can I get DC currents up to 20-30 A using a 9 V battery? ...
-4
votes
0answers
39 views
DC-DC Converter [closed]
We need a DC-DC converter IP 67:
-input voltage = 43-45 V; power = 200 W
-output voltage = 55-60V; power = 200 W.
We need to descend amperage from 5.7 A to max. 4 A.
Why?
We have two 100 W, 21,5 V, ...
3
votes
4answers
180 views
Do electrons actually flow when a voltage is applied?
It's said in books that a circuit is a closed path and thus that electrons come back to the source. If that's the case, what would happen when there were an earth fault in a circuit? How would the ...
1
vote
1answer
56 views
Logic gate using current source and diodes
This circuit is supposed to work as a logic gate. I need to find out the logic operation it performs. Suppose the diodes are ideal.
https://www.circuitlab.com/circuit/egg3wh/logicgate/
...
0
votes
2answers
62 views
Question about sign
I need to answer this question using PSpice:
It seems it's -15mA, BUT in the exercise, the current source is < (I understand it's + < -)
in Pspice I set it to < as well, but there is - ...
3
votes
1answer
92 views
Are there any rules of thumb when computing pulse current ratings for PCB traces?
Say I have a surface PCB trace, 4 oz, 50 mils. That trace should be able to carry around 15 amps continuous, according a calculator I'm using. (Obviously your trace ampacity estimates may vary with ...
0
votes
3answers
133 views
electric chewing gum prank circuit diagram
I'm new to electronics.
I'm trying to find out how this works out of curiosity.
http://www.amazon.com/gp/aw/d/B0050UNNQS
Does anyone have a circuit diagram for the circuit?
Is the current safe for ...
0
votes
2answers
66 views
Kilowatt hour from Complex power
How can I calculate Kilowatt Hours from:
Complex Power = 1,5 kVA
Electrical current consumption = 10 A
It's three-phase electric power.
2
votes
2answers
95 views
Using a transistor to add to max current output from a opamp?
I thought I understood transistors but now I'm confused again.
I have a basic opamp circuit to amplify the input of a electret microphone. The output of the opamp will vary within 1-4V. Now I want ...
-2
votes
0answers
47 views
Is this problem due to some kind of faulty ground connection? [closed]
The electric wiring is very old in a house and recently I have observed this strange incident: I connect a power strip (containing five nos. of three pin-sockets and a common on/off switch for the ...
0
votes
0answers
52 views
Small-signal input and output resistances of the circuit
I am given this circuit:
And I am trying to determine the small-signal input and output resistances.
I was either given or found all the following info for the circuit:
VA = 110V
β = 115
T = ...
2
votes
2answers
125 views
Is this switch circuit correct?
This is a follow-up question to How high is "high impedance" on this chip (CD74HC125E)
I finally decided to use a pn2222 transistor to act as a switch that activates the transmitter. The ...
2
votes
3answers
71 views
Computing Current from known Capacitance and Time to Charge to Known Voltage
If I know how long it takes to charge a capacitor of known size to a known voltage (within 10%), how do I find out the average current for that period of time? This only needs to be approximate.
...
1
vote
2answers
111 views
Current consumption in milliseconds
If I use 10mA for 40 milliseconds. How much current have I used in mAh (milliamperes per hour)?
0
votes
0answers
51 views
Electromagnet duty cycle
I have a project where I would like to use an electromagnet to lift an item for a longer period of time. I was looking at a magnet like this one:
...
2
votes
1answer
82 views
Anyway to Visualize Current without an Oscilloscope with that Function?
Having only an ordinary oscilloscope that shows voltage, is there any way to modify the circuitry or do some intelligent guessing to get an idea of what the current wave form looks like?
In my case, ...
7
votes
1answer
100 views
Should I use a resistor between an input pin of MCU/CPLD and VCC/GND?
Some times, I want my MCU or CPLD to input a static logic. So, I choose to tie it to VCC or GND. The problem is that should I put a resistor in series to limit the current? I just think by myself for ...
0
votes
1answer
117 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
148 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
92 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
97 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
56 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
45 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
35 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
83 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
65 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
73 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 ...
2
votes
1answer
90 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 ...
2
votes
1answer
88 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
222 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
121 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
86 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
366 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
101 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
155 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
102 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
384 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
181 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
57 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
74 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
67 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
155 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 ...
3
votes
2answers
128 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
75 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
141 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
115 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
126 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
167 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
60 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 ...
