# Questions tagged [voltage]

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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### Shocked by beginner circuit kit

I was trying to visualize a beginner circuit problem on my breadboard and I plugged in my circuit, touched a resistor and got a nasty shock. I am a cs student playing with circuits to build some logic ...
159 views

### Total voltage doesn't add up to 5V

I made a simple LED circuit with an Arduino Uno with a 220 ohm resistor. I measured the voltage across the outputs on the wires. It shows 5.08V. When I measure the voltage across the LED and the ...
74 views

### Why high current low voltage?

The company I work for started a new contract building SCR controlled power supplies. They have a 480v input that's transformed down to 12.5/15/17.5 V. In testing we can push as much as 2800 A on the ...
27 views

### Voh and Vol value in S32K142 Microcontroller

I'm having this S32K142 Microcontroller. 64 pin package. I have some trouble with the logic level compatibility between the above Microcontroller and the A80604-1 Backlight Boost LED Driver. ...
97 views

### Understanding a voltage multiplier circuit

I have a question about this circuit. I don't really know what it does. I have searched it up on google and I found something with voltage multiplier. I don't know what it does or if it is even a ...
35 views

### 1-5v throttle signal to 0-5v

I’m trying to adapt a new speed controller onto my motor. It uses 0-5v for the throttle input. The throttle I have now uses a hall sensor that can only do 1-5v so the motor will continue to roll even ...
65 views

### How to realize a negative voltage with a positive regulated DC output?

I found an AC adapter that converts 230V 50hz AC to +16V, 0V, 32V (3 pins) DC. I wanted to convert this into a +12V, -12V dual power supply. Someone suggested that I use a positive buck converter to ...
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### Analog mixer design help choosing between 2 states

I have designed 2 types of mixer an additive and a substractive one: The additive one is a practical application of Millman's theorem connected to an opamp: simulate this circuit – Schematic ...
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### Routing multiple video and power through one multicore cable

I currently have three cctv camera feeds each with a dedicated cable, I assume a 4 or 3 core of some layout (not sure if this is shielded or otherwise). Currently each cable has a dc pair end ...
81 views

### How can I calculate the voltage on the load in this circuit?

I've been try to solve this circuit for hours and have no idea on how to find the load voltage U_s. I tried applying the Thevenin theorem to find the equivalent ...
55 views

### What resistor is needed to regulate the current through 2 3V LEDs in series with a 9V battery?

So I'm trying to power 2 of these LED lights together in series. I know that I have to add the voltage of the two lights together and get a resistor that restricts the power to that level. I have a 9V ...
73 views

### Nominal voltage of a battery

How is the nominal voltage of a battery determined? A NiMH cell's usable voltage ranges between around 1.4-1.0V and the nominal voltage is quite in the middle of that at 1.2V. Similarly, the nominal ...
240 views

### How to vary the voltage output depending on the changes in temperature?

I am working with the Siemens Logo8! PLC (0BA8 version) and the purpose of my circuit seems to be simple: If temp > 25°C then output voltage = 8V If temp < 25°C and >15°C then output voltage = 5V ...
415 views

### Why is there a positive body voltage when grounded, but none when not?

So after reading about earthing and earthing mats, I decided to make myself a very basic one for cheap to test the concept before jumping in with purchasing more sophisticated products. Here's what I ...
6k views

### How to light a strip of 32 LCD backlight LEDs

Ok, for starters I haven't been able to find a lot of solid details about the LEDs I have here. All I know is that there are 32 of them; 8 LEDs per strip, in series, and 4 strips, each also in series. ...
20k views

### Under what conditions should we use negative voltage?

As mentioned in the title I'm curious and confused under what circumstances a negative voltage should be used? Does it mean in a negative voltage power supply the current is flowing from ground point ...
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### Battery initial state of charge after charge/discharge

I'm trying to estimate the initial state of charge for my battery (NiMh 9.6V @ 3300mAh) using the open-circuit voltage - state of charge discharge curve. I use an IC that measures the battery voltage/...
47 views

### If I supply more current than needed will my electronics fry [duplicate]

If I have a stepper motor and driver that require 5V and 240mA and I supply 5V at 3A will my circuitry die? I have heard the expression that a motor "draws" the current that is needs, but I ...
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### Question about outdated “amplidyne” technology

Can someone please help me understand something better about "amplidyne" technology that was used back in the day. What I know It appears to be a dc motor generator that acts like an ...
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### LED lighting for use in miniature tanks

Novice, built a model for a popular wargame. I built a modular tank using magnets for multiple variants from 1 kit. I hope to add some LEDs (max of 20 3V) & fibre optic lights on the vehicle and ...
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### Voltage on the Serial Link and Parallel Resistor Value

This question is related to the previous question that I had over here I found the serializer that I am using. It is over here From the above serializer datasheet, on page 9, I found that the maximum ...
368 views

### 10S1P issue - battery not charging

I recently bought a E-board (electric skateboard) which would not charge. I opened up the battery compartment to check the voltage of the batteries. In case of an undervoltage which led to them not ...
1k views

### How to convert exponential output to linear output

I have a sensor which gives me roughly exponential output from 0 to 6 volts. How would I convert this to a linear range?
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### Does voltage travel from the HERM terminal in the capacitor to the START winding or to NEUTRAL?

I have an AC and it has a dual capacitor. The compressor terminals and the fan terminals are connected to it. Does anyone know if the voltage flow (when the compressor gets power) from the HERM ...
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### Auto Voltage Selection between 12V and 5V for Irrigation Controller

Background I am working on a hobby project, it will be a general purpose open source irrigation controller. I haven't built the PCB yet but I want to power the board either through the USB port for ...
179 views

### Bypassing a voltage regulator if input voltage is too low

For my project I want to allow the user to either use a 12 or 24VDC power adapter if needed but I dont want to make 2 seperate DC inputs. Neither do I want to use a buck-boost because I dont want to ...
59 views

### Use household power strip for 12V/24V power

I have a 12V/24V dimmer (rated 60W) and need to hook up 8 different lights, can I just use a regular power strip to distribute the 12V/24V? the power strip of course says 230V on it, but does it ...
172 views

### L293d, Input Voltage Specification

I have made project " DTMF Based Land Rover ". The whole circuit is working in usual manner. The voltage at arduino output pins is 3.46 volts. And pin no 16 and 8 are Vcc of L293d respectively So ...
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### Voltage on the serial link

I am using this MAX9278 deserializer. The inputs to the IN+, IN- pins of the deserializer are twisted pair inputs. On the IN+ and IN- serial link, I have 2 AC coupling capacitors of 220nF 50V on each ...
37 views

### Powering a NEMA 17 motor | Wattage Vs Voltage

I apologize if the question is silly as this is my first project involving stepper motors and I'm confused about power supply specifications. So I'm working on a project involving: 3 NEMA 17 Stepper ...
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### Voltage gain from AC

Voltage gain CE & CC from AC Can you tell me please if I am true in calculation of gain of this circuit? Assumption: gm is known and beta=inf, Early VA=inf => gbe=0, gce=0. Here the Matlab code : <...
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### Electric shock and ground potential question

Why don't I get shocked when I touch my phone charger cable connector while the switch is still on? What happens if ground potential is not 0V (e.g. 150V or lower or higher?) Will the energy still ...
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### Simplyfing a circuit by replacing two nodes with a voltage source and removing a connection between resistors

I am given the first circuit (A) and I have to find the voltage across R4. Since the potential at node C is independent (V2), I was thinking about a possible transformation to circuit B. However, I am ...
55 views

### Can you cross Live and Neutral traces on opposite sides of a PCB?

Can 230V live and neutral traces be crossed over if they are on the top and bottom side of a PCB? I know there are requirements for creepage and clearance; if that requirement is less than the ...
207 views

### Voltage divider network calculation

Hello I am troubleshooting a voltage divider circuit in which I know the output going to U28 pin 3 should be around 700mv. What I am measuring however is around 7.5v. How do I calculate the v out for ...
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### External transformer for PCB made for someone else a few volts higher than circuit was designed for, will this damage the optoisolators?

I sold my first PCB to someone for a bowling lane project. This PCB has 10 opto-isolators(LTV-817) which are connected(after going through a bridge rectifier) to external switches going to a ...
44 views

### How to determine the rated voltage for 3 phase motor

I have an unlabeled 3 phase motor (based on the size probably 5 HP) with 3 pairs of wires and a schematic picture for wye and delta connections. Since there’s no label I have no idea what the rated ...
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### How to mitigate/stop voltage spikes when turning AC transformer on and off

I wish to use a certain transformer in a project of mine but when I power the transformer on or off I see a series of large voltage spikes on the oscilloscope. The project is a DC power supply. The ...
44 views

### Laplace and KVL

I was preparing for my exam by solving questions and there is this one question I was stuck on but when I saw its solution provided by book, I think KVL applied is not right or I am not able to ...
129 views

### How to select standard resistor values for a voltage divider?

I wanted to select resistor values for a voltage divider that sets the output voltage of a buck converter. I picked the values recommended in the datasheet, because 3.3V is a standard value there were ...
847 views

### No potential difference between the negative terminal of battery A and positive terminal of battery B?

I know that if you have two batteries, battery A and battery B, and connect the negative terminal of battery A to the positive terminal of battery B, there is no potential difference. If you consider ...
2k views

### Power 15 meters of LEDS?

I'm trying to make a display out of 2811 LEDs from China (15 meters long x 7 LED strips). Each strip consumes 18W@5V(3.6A) per meter and I plan to use 7 strips, each 15m long. My calculations show we'...
47 views

### RMS value calculation of 3 phase line voltages for power calculations

In my textbook in the power calculations section of the balanced three phase circuits, a part confused me a little bit, it is this part: Why are we dividing by $\sqrt{3}$ to find RMS values of \\$V_{...
13k views

### Silicon Diode Threshold Voltage 0.7

I have wondered myself why is that value fixed to around 0.7 V (0.3 Ge). I have researched about this topic over and over again, but I always find the same answer. They say "Because the voltage for ...
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### Can anyone help clarify all the values on these rating labels?

I am doing some small asssignment for my class. But I am bit confused about the power ratings on these two labels. For example, the first label, I used P=VI to calculate power. So P= 12 * 1= 12 [W], ...
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### How do appliances prefer to use my solar power from a grid-tie inverter over the power from the grid?

I have a grid-connected solar inverter. In the swtich board the incoming wire from the street, the incoming wire from the inverter and the outgoing wire to the loads in my house are all connected ...
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### how to find voltage difference between two points(Ethernet) by using two single-ended on oscilloscope [closed]

I have an MDO 4000(Tektronix) and two TPP1000 probs, I am trying to do a trigger on an Ethernet cable. I connected the first prop on the color (orange/white-orange) and the other on the color (blue/...
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### How can I calculate V1 and V2 in this circuit?

How can I calculate V1 and V2 in this circuit? This is what I tried so far: Calculate the voltage of R5 through voltage divider but I didn't find the way, I was looking about second OA circuit but ...