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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How to reduce 28v to 24v under load?

I need to PWM control six 24v DC fans with a total load of 10.6 amps. That's easy, right? Just PWM to a few MOSFETs. However, my system voltage is 28v. At 28v I'm out of spec for the fans and ...
2
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1answer
88 views

When is voltage level shifting needed/unneeded?

I know the question sounds simple, but I am facing an edge case here. I have a microcontroller with 3.3V on the GPIO's. I want to use it with this LCD panel. Adafruit creates their own breakout board, ...
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3answers
69 views

How to find the positive wire on wall charger

i have a TPLINK wall charger from my old router. It's almost new and i would like to use it for my 5V regulator project. The prboem is that i dont know which of the 2 wires is positive and which ...
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6answers
151 views

Batteries in parallel vs voltage signals in parallel

From a practical point of view, when you connect two audio signals to one speaker the result is that both audio signals can be heard. That means the two voltage waves were added, correct? However, ...
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0answers
28 views

Dual power sources to 12V batteries in MPPT solar setup? [on hold]

I have 12V batteries charged by a 1KW 60V solar panel array. The system uses an 80Amp MPPT solar charge controller. I would like to add a secondary power source - possibly a 12V peltier based ...
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2answers
65 views

Converting Voltage [duplicate]

I have a pair of batteries that can operate at 7.2V (series) or 3.6V (parallel) and I need to power up a device using 5V. I can use a Voltage Regulator to down voltage at 5V or I can use maybe ...
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1answer
69 views

Why is voltage 0 after the last component in a circuit given electron current flows from negative to positive?

Perhaps a different way to ask my question is why does voltage drop occur on the negative side of a component and not the positive given what is known about electron current? E.g. in the diagram below ...
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34 views

Powering high power LEDs [on hold]

I want to power some high powered LED (R2) with this circuit. I would like the LED to be on for about 1 minute and they discharge C1 via R2. When C1 charges SW1 is open and the LEDs are off. When ...
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2answers
66 views

How to reduce current

I need help reducing current in my motor driver. The chip is the L293D motor driver with output max 600mA. My stepper motors draw maximum 350mA per phase and operate at 12V, so I am concerned about ...
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1answer
41 views

Enable pin with maximum 3.0v

I've an Enable pin active-high that have maximum voltage rating of 3.0v, but I use a 3.3v MCU outputs. I've also a 3.0v voltage regulator on board. Should I use resistor voltage divider or there is a ...
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3answers
132 views

Can I visually obtain an equation from this curve?

While I was in the lab I was able to get the correct voltage curves on the oscilloscope, but time was short so I took a picture instead of measuring the voltage incrementally (the ultimate goal being ...
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3answers
204 views

Max voltage vs current for LED

There's some basic flaw in my understanding of how LED's or diodes in general work so hope someone can help and forgive the simple question. So generally when one has an LED in series with a ...
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2answers
107 views

Voltage regulator from 24v to 3.7v [duplicate]

I need to build a simple voltage regulator that can drop voltage from 24V(from a DC power supply) to 3.7V and supply at least 2A or more(up to 5A if possibile). Can I just use a 2 resistor voltage ...
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2answers
45 views

Full wave AC Voltmeter Vs True Rms Voltmeter

Does a full-wave rectification AC Voltmeter give the same indication as a true rms voltmeter when you measure a 50 Hz sine wave?what happens if the the sine wave is clipped by an inadequate ...
1
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1answer
67 views

Why does the volatge drop is huge once a load is connected to a generator?

At no load condition the generated voltage at transformer secondary output is 140 V ac. When a 60W resistive load is connected the voltage drops to 27 V ac. The pmg generator rating is 1 KW 415 V and ...
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2answers
55 views

how can i decrease the voltage of an AC-DC adapter without decreasing current (mAmpire)

i have an AC-DC adapter with 5volt 350mA (actually an old cellphone charger). i need to decrease it's voltage to 3volt. i tried adding a resistor in series & it worked, but it also decreased the ...
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1answer
91 views

Is using a transformer at reduced voltage a bad idea?

My Google is failing me. I want to make an isolated AC voltmeter capable of working at 120 or 240 VAC. I've found a suitable 240 volt to 5 volt transformer to use (current capacity doesn't matter - ...
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1answer
49 views

What can be the reason for a voltage drop across daisy chained RS485 servo motors?

We are using a set of RS485 servo motors(Robotis EX-106) for our humanoid robot. This motor has a 4 pin connections namely Ground,VCC, D+ and D-. The Ground and Vcc terminals are from the power ...
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0answers
40 views

switching of mosfet using IC TL594

Switching of mosfet using IC TL594 I can't find the required circuit diagram switching of the MOSFET using an IC. Is it good to use the PWM method for switching ??
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2answers
56 views

Induced EMF of a slope wire?

If a single wire is moving at \$v\$, inside a magnetic field \$B\$, with length \$L\$ then induced EMF is:$$\epsilon\ = -vBL$$ That is for a vertical wire that's motion is perpendicular to a magnetic ...
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1answer
68 views

How to determine DC motor voltage

I am building a new controller for an existing robot. I need to know the voltage to send the motors. I don't want to remove the motors from the robot, but am able to take measurements while it ...
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3answers
82 views

Circuit Starving Question

I have a circuit where 2 DC motors are connected to 4 AA batteries and being controlled by an Arduino microcontroller. Whenever the motors start, they starve other components in the circuit and it is ...
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3answers
95 views

Can voltages be different if watts are the same? Does DC vs. AC change this?

I'm currently building a home in a van, it's my first tango with electrical engineering. I watched a video on voltages and amps and my understanding is basically like so: a battery is like a water ...
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0answers
84 views

Voltage Doubler Circuit

I currently have a 25 stage voltage doubler circuit I am using 50 0.1 uF x2 suppression capacitors, 50 1N4007 Diodes, and a 20 Mohm current limiting resistors at the final emitter stage. I am using ...
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2answers
80 views

Discovering operating power of a component without destroying it and without specification

I have a laser pointer component that I figured was a 9V pointer, and it worked nicely and shone very bright. I kept decreasing the voltage to see how low it could go, and it turns out it runs great ...
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2answers
63 views

60VAC resistive load (heater) on 220VAC?

I need to run a ceramic fiber heater (Watlow part number vc401a06a, datasheet) at 220VAC. This particular part is rated at 60VAC, for 220W. Can I safely use this on 220VAC, if I'll be controlling it ...
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6answers
160 views

How do you find the voltage across a capacitor at time t= 0 and t = infinity?

Here is a diagram of the circuit, I am confused about problems a and b. How do I go about solving these two problems? Thanks! By the way you don't have to tell me the answer, I just want to ...
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4answers
143 views

What will happen to a transformer if rated output voltage is injected to the secondary terminal?

I believe that I have a three phase delta to single phase transformer 1Kva with input 415 v three phase and output 230 Vac single phase. ( Someone help me to identify what kind of transformer is ...
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2answers
146 views

what happens with diode voltage drop when connected directly to constant voltage supply?

The diodes usually have voltage drop of about 0.7V or so, which is said to be constant for some type of diode (ie. not depending on voltage/current). So what would happen if one connected a diode ...
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5answers
113 views

How do voltage, resistance and amperage work? (In DC circuits)

I have a (probably newb) question that I can't figure out. What I think I know is this: Voltage is electric potential (or rather a difference thereof) Amperage is the rate at which electrons move ...
2
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3answers
139 views

How does a flame sensor or thermocouple operate with just one wire?

I am learning electronics and I just got stumped. I was just looking at a flame sensor and it appears to have only has one connector. I thought sensors in general need two wires to form a complete ...
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1answer
46 views

Li-ion Battery charging process [closed]

Why are constant current mode and constant voltage mode needed when charging Li-ion batteries? Why do we apply saturation charge even after the cell voltage reaches 4.2V? What exactly is 'I-sense' ...
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3answers
84 views

Instrumentation Amplifier Level Shifter

I am working on a temperature measuring circuit using a pt100. The input of my instrumentation amplifier (AD8226) is between 80-200mV. The Gain is set to 20.84 so I get an output range of 1.7-4.2V. I ...
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2answers
158 views

Voltage regulator up to 100v? [closed]

I want to make a power supply that outputs 90v DC, and I was looking for a 0...100v voltage regulators, but I don't find any...? How can I achieve this if I can't find them? The input voltage of the ...
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1answer
52 views

Choosing Correct Switching Power IC for 5v 2A Output from 2S Battery

I am designing a Power Circuitry for a Application that needs to feed 1x Beaglebone Black (5v), 1x Device with 600mA (5v), and 2x XBeePro Modules (3.3v) via a 2S (7.4v 1Ah LiPo) Pack. The Plan ...
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4answers
451 views

Why do I need a delay as PIC powers up?

I'm using a low-power PIC16LF1554 together with an nRF24l01+ 2.4GHz transceiver. During power-up, the PIC will try to initialise the RF module before the supply has reached the required minimum and ...
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0answers
27 views

Voltage Across Patch Antenna and Power Output

I'm modeling a patch antenna using two copper plates (ground plane and patch), ceramic in between the copper plates, and a lead connecting the patch and ground plane that runs through the ceramic in ...
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2answers
95 views

How to power a 12V6A peltier device with a 14.4V battery?

How to power a 12V6A peltier device with a 14.4V battery. My son is working on a school science project and unfortunately I have very little knowledge on electrical engineering. Please be patient ...
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3answers
137 views

Is there a way to adjust the DC Voltage

I have a source (1) of power which can be adjusted from 1-5 Volts and 40 mAmps. I have another source (2) of power which delivers a constant 5 Volts and 400 mAmps. I want to build a circuit which ...
1
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5answers
128 views

doesn't ohm's law applied to every thing? [closed]

I've read that voltage is high in step up transformer due to greater no. of turns it makes sense but why it reduce current?I have done a lot of search on it but there is only one answer.that is to ...
0
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2answers
96 views

What is TBD power, TBD power, TBD

I was reading up about a processor spec and I came across the acronym TBD. On googling, i could only find only colloqual explanations, but nothing solid. Here is one research paper link ...
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2answers
122 views

Bench DC power supply output

I recently purchased a ATTEN APS3005D Regulated DC power supply from eBay and I'm having some odd and potentially alarming results that I'm trying to get my head around. Note: I'm testing this ...
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2answers
50 views

Voltage shifting from 5V to 1.5V

I have a 5V TTL which is basically a trigger output that I want to give to an FPGA I/O pin which takes 1.5V, 10mA. What's the best way to do it and what's a quick way to do it ? I was able to look up ...
0
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0answers
51 views

Calculation of line-to-ground voltages from line-to-line voltages

I'm studying Electrical Engineering with the specification on Energy and Drive Systems in Germany. I currently have a task to develop a program, which gets some three-phase Voltages (line-to-line ...
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2answers
72 views

transistor voltage drop

I'm having an issue with a transistor. I'm apply ~3.3v to the base, 4.7v to the collector, but only getting ~2.5v from the emitter. I need to be getting close to the full 4.7v I'm aware there is ...
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0answers
29 views

In trying to fix my laptop power adapter, current is going through the wire but the laptop will not charge? [migrated]

My laptop power adapter has recently stopped working (will no longer charge my laptop), and I would prefer to fix it if possible, instead of putting a couple hundred bucks into a new one. I used a ...
0
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2answers
68 views

Can I feed lower than rated voltage?

I'm poking around on eBay for some capacitors to use in circuits which I'm working on and see that they have a rated voltage. After some quick research, I found that going over the rated voltage of a ...
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0answers
25 views

How to protect my home from high voltage? [migrated]

Hello and sorry for my bad english :( My household circuit has an effective voltage of about 220 volts most of the time.(98% of the time).There are cases when the voltage is to high 250,300,350 and ...
0
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1answer
105 views

How much resistance will I need to drop the voltage?

9 Volts is applied to circuit. There is an LED which runs on 3 Volts. I want to drop 6 Volts. how much resistance (\$R_1\$) would I need for that?
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1answer
61 views

Powering a rechargeable battery with a solar cell

just a short question. I have a solar cell that outputs 7V. I want it to charge a 9V battery source. Is there anything I should be worried about or take note if I try to do this?