Voltage, otherwise known as electrical potential difference (denoted ∆V and measured in volts) is the difference in electric potential between two points (adapted from Wikipedia). Voltage can be constant (DC) or varying (AC).
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127 views
Do I need to double the voltage with double the motors?
I am totally new to electronics.
Let's say I am building a DC circuit with a motor using 6V taking 1.28A.
Now, if I build a circuit that uses two of these motors, will I power the circuit with 6V and ...
2
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3answers
143 views
Lowering voltage linear [duplicate]
Possible Duplicate:
How can I use a 12 V input on a digital Arduino pin?
I want to measure a car battery voltage (range is between 10-13v). But my AVR accepts analog inputs from 0-5v. How ...
2
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1answer
273 views
Battery Power for RC Car
I'm working on a school group project which involves setting up a remote controlled car with a BeagleBone, webcam, WiFi module and a powered usb hub.
To handle the mechanical side, we bought a cheap ...
5
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2answers
94 views
Scaling voltage to meet two conditions at once
I am using an IC (STM6600) which, among other functions that I need, is also capable of Undervoltage Monitoring. It works like this:
The IC monitors VCC in comparison to two thresholds, V_Low and ...
2
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2answers
89 views
Maximum effective range of RG-6/U in CCTV
How long RG-6u i can use in my cctv? what's is the effective range using RG-6u?
4
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1answer
90 views
Input and Output pin voltage specs on a datasheet
I'm a bit confused about input pin voltage tolerances and output pin voltage values of ICs.
I would think that datasheets for ICs that involve signal inputs/outputs would list two values:
The ...
4
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1answer
227 views
How to Protect an ADC Input from Overvoltage
I have a module with an ADC with a maximum input voltage of 2V. I would like to monitor the battery voltage of 15V with this input. I have successfully used a trimpot as a voltage divider to ...
6
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2answers
128 views
Setting a part's VCC slightly lower than board's supply voltage
I'm interested in using the undervoltage detection feature (in addition to the primary function) of this chip. This IC draws 6 uA (microamps), and accepts any VCC between 1.6V and 5.5V.
The ...
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1answer
121 views
Which fuse and LED should be used for a no contact testing screwdriver? [closed]
I'd like to make my own testing screwdriver based on an existing one which has 2x LR41 batteries, a 2.2Mohms resistor, a KSP13 Darlington transistor, a 5x15mm fuse and a red LED. It works for ...
2
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2answers
108 views
Interfacing signals between two parts at different voltage levels
I would like to connect four output pins of a certain IC to four input pins of an AVR microcontroller (Atmega328).
I'm running the IC at VCC that varies between 3.50V and 4.00V. It outputs signals ...
3
votes
1answer
155 views
How to use an audio codec as an ADC?
I would like to add ADC functionality to a TI C6748 dev board. I need 16bit precision, but relatively low sample rate(~5K).
Not finding any suitable daughter ADC card, I am considering the ...
0
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1answer
169 views
Need help designing a current controlled source in PSpice?
The image below shows an electrical network with 8 elements, a current controlled source, a bunch of resistors, one current source and a voltage source.
Although I haven't labeled them, there are 5 ...
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3answers
383 views
What is the lowest capacitor voltage rating that is safe to use?
I'm using a few Case R tantalum capacitors (10uF 6.3v) as bulk decoupling on the 3.3v power of a 100mbps Ethernet phy. I am also using 0.1uF ceramics closer to the pins.
As usual, I'm terribly ...
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1answer
52 views
Wrong voltage sent to output
Using miniLab1008, I am trying to send 10V to my D/A OUT0 but it sends only 5V and when I send 5V, I get 2.5V. I am using the universal library example VOut01.c
Is this a board problem? However using ...
1
vote
1answer
159 views
Connecting arduino to power another device
I have an arduino board which I want to use to give power to a device which uses two 1.5V batteries. I think I have to remove the batteries from the device and control the power supply via arduino, ...
3
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2answers
175 views
Stepping from 5 V / 1000 mA to 3 V / 750 mA
I'm trying to go from 5 V, 1000 mA, which is a USB transformer for Apple devices, to 3 V, 750 mA (which is a small camera I have). I have purchased a NTE1904 3 terminal volatage regulator which 3.3 V, ...
6
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1answer
131 views
Why do standard cells typically have slower timing with high temperature, and faster timing with low temperature?
Threshhold voltage typically falls with increasing temperature, which would seem to indicate that high temperature operating conditions should result in faster gates than low temperature OCs. However, ...
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3answers
230 views
using led stripes with external battery: any side effects?
i have to power some led stripe from ikea with a drill battery:
On led stripe power is written: 12V 0,25A. and on drill power: 12V 2A.
Now i want to power n led strip (for example: n=4) and i ...
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3answers
484 views
Why is the voltage across a reverse biased diode equal to source voltage?
Why is it not equal to zero since a reverse biases diode is essentially an open circuit?
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2answers
6k views
230V AC to 5V DC converter, lossless
Is there any IC which converts 230V AC to 5V DC? As lossless as possible. I want to connect my microcontroller to an ordinary electrical socket and I don't have enough space available. Thanks.
6
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1answer
398 views
Center tap split supply question
Lest's say that I have the following setup:
a split supply (using two voltage regulators: a positive and a negative one) connected to a center tapped transformer (12-0-12). The output of the ...
1
vote
1answer
108 views
diy 110 volt tester
I want to copy a 110volt tester I made in the 7th grade.
It consists of one small bulb and I believe one resistor.
Both fit inside a small tube(transparent gas line) with two leads coming out. I need ...
3
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1answer
119 views
equivalent load resistance
I have the following circuit
I am having some trouble determining the relationships between Iac, Io and Iacpk. I'm not quite seeing how the final equation for Iac was determined, specifically ...
3
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1answer
121 views
Identifying an irreducible circuit?
How would you go about identifying an irreducible circuit? By irreducible, I mean combining resistors whether in series or in parallel to reduce the circuit.
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2answers
354 views
What is meant by relative voltage?
Suppose you have a circuit
,you are told that the voltage at point 2 relative to point 1 is -90V, the voltage across R2 is -30V and V0 is 200V.
What is the meaning of voltage at 2 relative to 1? ...
2
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1answer
192 views
Voltage/Amperage load rating
I'm a newbie when it comes to electricity, and this has been bugging me since like 9th grade when I first learned about V/I/R/P combinations, and to this day I still can't wrap my head around the ...
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1answer
151 views
What's passive about the passive sign convetion?
I've heard and read about the passive sign convention, but don't really understand its meaning and importance in solving electric circuits. Is this because of conventional current which flows ...
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1answer
182 views
diode nightmares
Let me start by saying I am a complete amateur trying to stumble my way through some pretty basic PCB design, and I have run into a problem selecting diodes. The PCB I am designing will be for some ...
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2answers
176 views
What use is the reference node in nodal analysis?
Rules for identifying a reference node in a nodal analysis of a circuit include;
Node with largest # of elements
Max # of voltage sources
Node of symmetry
My question is, whats the point?
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2answers
1k views
Driving a large 7 segment display using a micro-controller
I need to drive a large seven segment display (segment length is a about 2 inches) using a micro-controller (PIC 16F877). I've driven normal seven segments directly from PICs without issues, but I ...
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2answers
136 views
Current/milliamp rating of adapter versus device requirement [duplicate]
Possible Duplicate:
Choosing power supply, how to get the voltage and current ratings?
My DC adapter for a cordless mike has broken It' ratings are:
Input 230-240V ~ 50Hz 30mA
Output 20V ...
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1answer
264 views
LT3080 regulator question
The datasheet of the LT3080 voltage regulator says that "For true zero voltage output operation, this 1mA load current must be returned to a negative supply voltage."
What exactly does this mean? How ...
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2answers
479 views
3.7 Volt external battery to charge a another 3.7 Volt Phone Battery?
I would like to know if a 3.7 V external Battery would be able to charge a phone battery of the same voltage. From my understanding, the batteries would charge each other until the charge in both the ...
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1answer
242 views
'Voltage Fuse' or better
I have a power supply with multiple outputs (5v, 12, 24v)
According to the manufacture (and after testing) there must be a minimum load on the PSU for it to supply the stated voltages. Without a ...
5
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1answer
305 views
Connecting multiple grounds
As I'm relatively new to the electronics world, I was wondering if you can connect multiple ground terminals (corresponding to several different voltage outputs) to the same ground. Or do they each ...
3
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1answer
214 views
Battery in parallel with main power source
I have a system that is powered by a main voltage supply and I want to connect it to a battery for backup, in case of power outage.
I need to know what would happen if I connect the system with the ...
5
votes
1answer
344 views
Laptop power supplies - why the spectrum of voltages and connectors?
Why do are laptops designed with different Voltage input requirements? Is this just a power requirement consideration, or something more technical? Maybe the lithium battery requirements? (And - for ...
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1answer
165 views
Why is voltage inverse to current in a shunt generator?
Here is something I read:
Current in the field windings of a shunt-wound generator is
independent of the load current (currents in parallel branches are
independent of each other). Since field ...
2
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3answers
514 views
Step up DC/DC 5V -> 6V
I have a circuit that runs 5V. I need to integrate a CO2 sensor that requires 6V. What would be the simplest, most cost effective way to do this? I need about 200ma for the sensor
0
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1answer
310 views
Multi-tap transformer current handling capability
I have a transformer with a single secondary winding but with multiple taps, as shown in the image.
It is rated at 4A @ 24V (96VA).
Does this mean that at lower voltages (16V and 8V) it will be able ...
6
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4answers
542 views
MOSFET Switch w/ Fast Settle Time for Switching E-Field
Application:
I have a copper mesh (10cm x 10cm square) in a vacuum chamber connected to a BNC connector by a 24-cm-long copper wire. The goal is to switch the mesh voltage (referenced to ground) from ...
6
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2answers
424 views
Why does a printer's inrush current double for 240V vs 120V?
In this answer, the inrush current for a laser printer is listed as follows:
...
4
votes
4answers
371 views
Replacing a switch with a transistor
I am working on a project on the Raspberry Pi, it is a bit experimental as I am learning the electronics side as I go along... please edit out any problems with terminology.
My aim is to replace a ...
3
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2answers
196 views
Current path question
This may be a stupid question but it seems that I don't have a clear image about how this works exactly.
So my question is:
In the attached schematic, why will there always be a higher current in ...
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4answers
244 views
Share battery between different voltage devices
I have a keychain-sized China-made camera that has an internal LiPo 3.7v dc battery, and a TI MSP430 microcontroller that operates between 1.5v and 3.6v dc. I want to use the microcontroller on the ...
2
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2answers
132 views
Negative Voltage Breakers?
I've been reading a bit on negative voltage, but I have a question that will probably reveal some ignorance, so I apologize ahead of time. If someone tells me that they want a (2) 5A breakers, (1) ...
2
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1answer
120 views
Inductance of a HDD BLDC Motor Phase
So I have set up a little experiment which involves a HDD BLDC Motor, a scope and a multimeter. Pretty simple, I know. Is it possible to determine the inductance of a phase by the voltage the phase ...
2
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3answers
305 views
Difference between voltage and current ratings on a component
This is a pretty basic question, but I'm new to electronics, and I'm a little confused: if you have a component that say it runs at 12V, it still needs a certain amount of current to run, right? If ...
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1answer
77 views
which battery will supply the load?
I have connected 14V supply terminal from alternator to 12V battery terminal and has taken the load across these terminals . But the load is operating still in 12V, and when measured across the ...
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3answers
263 views
How to calculate series resistor to provide a certain voltage to a pin?
I (theoretical physicist, all the basic theory, no further electrical engineering background) am just diving into Arduino and I have a very basic question:
I am playing with a Zilog ePIR motion ...
