# 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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124 views

### How can capacitors pass AC without or with minimal voltage passing?

My question is: How can capacitors pass AC without or with minimal voltage passing? If the current is caused by a voltage (potential) difference and current is just the voltage (or charge) passing per ...
73 views

### TX and RX on single wire

Here I am not using any RS232 or RS485 protocols. I will transmit analog square signal of -12 to +12V and also receive the -12V to +12V signal. So I have a circuit which can transmit and receive the ...
68 views

### What to do with unused open drain pins

I have a light sensor IC. I have 2 questions: The I2C Lines is connected between the microcontroller (3.3V domain) and the light sensor IC. The microcontroller is placed on a PCB and the light sensor ...
67 views

### It okay to use 12V 2.5A adapter instead of 12V 1A? [duplicate]

I have a piano keyboard that uses 12V 1A adapter . The adapter was not working anymore so i used another one which was 12V 2.5A but after 45 minutes of usage the keyboard got little heated up in the ...
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### Differential Impedance Matching

Below is a small portion of a schematic which I have seen It mentions that the transmission line will have a differential impedance of 100ohms between them. In case of Single ended it would be 50 ...
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### Twisted Pair input routing on PCB

I have a twisted pair input to the IN+ and IN- pins of the MAX9278 deserializers. The Parallel data output of the deserializer consists of 4 LVDS data channels and 1 LVDS Clock channel to a 3.1" ...
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### reduce voltage for inverter in solar system

I have a solar system (solar panel, controller, battery and inverter). Battery have standby use 13.6-13.8V, cycle use 14.5-15V. I set the charging voltage to 13.8V. The problem is that inverter to 230 ...
48 views

### How to get started knowing how to power my robot? [closed]

I have been a software engineer for many years writing code for websites/servers etc. I recently became intrigued with the idea of building land drones. I have decided to build a small tank that has a ...
98 views

### Case fan making humming noise when used with potentiometer

simulate this circuit – Schematic created using CircuitLab When I turn on the circuit above, when the potentiometer is not at minimum or full speed, the fan makes a high-pitched whining sound, ...
58 views

### Battery Packs not showing any voltage on multimeter

I made 4 battery packs with 10 batteries in series each using a spot welder. Each of the batteries in each pack are 1.37V, but when they are connected, the voltage is shown at zero. I took the ...
41 views

### Power of a controlled voltage source

I'm learning a bit about controlled sources and I'm a bit confused about calculating their power. I have this circuit. Link to Falstad Simulation According to the formula for power P = U * I, I get ...
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### How to stop ESP32 resetting when motor starts?

This is my first post here and I'm new to electronics. I am trying to control a motor using an ESP32 Cam. See attached image for a rather crude schematic. The power supply is rated for 2.4A. I am ...
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I want to read input voltage from a solar array for my circuit. That's not a big deal if the voltage is up to 3.6V. The problem is that I am expecting maximum of 15V and obviously I won't be able to ...
57 views

### How is the output voltage adjusted on this schematic?

This is a schematic of TI's reference design for a 65-W USB Type-C high density active clamp flyback with GaN (PMP21639), which can be found from this reference design page. The page claims that the ...
51 views

### Do switches induce voltage spikes in the AC power grid?

I know that DC inductive loads create back EMF when turned off and that's why we use a freewheeling diode. Does this also true for AC inductive loads and AC loads in general? I know we can't use a ...
80 views

### Why can't KVL be applied here?

I was asked to find the Is current I applied KVL in that loop but my ans is wrong. what concept is wrong on my approach?Why kvl cant be applied on that loop please explain
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### Voltage multiplier circuit not working

I am trying to make a voltage multiplier circuit. When I connect it to mains $120 \; V$, the output voltage becomes $90 \;V \;DC$, I do not know why this is. Capacitors: $20 kV \; 1000 \; pF$ ...
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### How do I determine which microcontroller can help me measure peak to peak voltages for my 400 kHz sine wave signal? [closed]

I have 400 kHz sine wave signal with a variable voltage between 0 V to 5 V, and I would like to use a microcontroller to measure peak to peak voltage of the sine wave. My understanding is that the ...
64 views

### Make time auto shutoff PC fan - safe?

simulate this circuit – Schematic created using CircuitLab I am making a fan that shuts off after a minute or two, but is this circuit safe for the fan? It runs at full power at first, but as ...
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### Driving 18 Thermistors in parallel

I am designing a circuit that needs to have 18 thermistors to measure the temperature at various points. The thermistors are 2metres+ away from the ADC Usually when I power a thermistors I use a Vref ...
99 views

### How does current flow in this circuit

I'm just trying to visualize how the current flows in the following circuit. It is a follow-on question from here. The circuit is a small-signal model for a common-source MOSFET with source ...
107 views

### Connecting PWM computer fan to transistor and adjustable resistor

Edit: Please do not change the circuit after the circuit has been discussed and answered. Thank-you. --MathKeepsMeBusy simulate this circuit – Schematic created using CircuitLab I'm making a ...
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### Build a circuit to modify a printer's power supply

Can I in anyway build a simple circuit that would change the printers power supply to be able to power the printer in the photo? I want to convert a 22V 455mA power supply output to 16V 500mA output ...
105 views

### The relation between Vin and Vout (diodes circuit)

Can anyone here tell me if the function I found that relates the Vin to Vout is right? So I made a mesh analysis to find the current in the first mesh (left to right) and in the second and got that ...
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### Deserializer Datarate calculation

I am having this MAX9278 deserializer IC. The input to the pins +IN and -IN is a twisted pair input and therefore, it is a differential signal. I have configured the CX/TP pin to low since it is a ...
28 views

### Working of Comparator and LED Driver pin function?

I have this LED Driver - A80604 I need to generate 30V for my LED Driver String for generating 300mA. My question 1 - Both pins ADIM and PWM seem to perform the same function? Both typically take in ...
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### Driving multiple LEDs from microcontroller pin

I have a 12 V supply and I want to connect 4 LEDs to each pin of the microcontroller. Voltage and current of each LED is 2.5 V and 20 mA. When the output of the microcontroller becomes high the LEDs ...
62 views

### Determine a known battery's instantaneous capacity through voltage? / voltage's relation to capacity

Is it possible to approximate a battery's current (the "right now" kind of current) capacity, given its absolute capacity and a voltage measurement? An example: I have a 1s 260mAh LiPo that ...
108 views

### Why does current continue flowing in a circuit?

Sorry for the amateur question, but I'm having trouble understanding this phenomenon. In a closed circuit, electron current flows from the negative terminal of a battery to the positive terminal. But ...
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### Will diode be turned on? [duplicate]

Assuming we have this circuit: simulate this circuit – Schematic created using CircuitLab Assuming D1 is a silicon diode and D3 is a germanium diode,Will D1 be turned on so the VAB = Vfd1 or ...
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### Why would you protect a 120-277 LED driver with a fuse that is 600V rated

Sorry about the silly question but is there a reason why you would want to protect a 120-277V LED driver with a fuse that is 600V rated? Does that really protect the device/driver?
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### How to prove that the $3$ nodes have the same potentials?

The question of symmetry. The each resistor has the same resistance(given by $r$). Why a current doesn't flows between the each endpoints of the middle $2$ resistors? The text book only states of ...
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### What will be the output voltage graph of the following circuit if output voltage is considered across the resister?

The circuit is given below. I know that until the Vin reaches the first peak, the voltage across R (output voltage) will be 0 since capacitors draw current to charge. After that, I couldn't figure it ...
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I've got a motor driver controller, I found an SMD component that is the same component shown in the picture. I need help identifying this component. I've tried to google the part number, but no luck.
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### How this equation of the voltage is attained?

I've may been asking the very easy question. The each resistor has the same resistance(given by $r$). The textbooks states the following. $V_{AB}=r\{i_1+i_2+i_3+(I-i_1)\}$ How the above equation ...
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### Question on H bridge motor circuit

I just finished task 1 on my project but my teacher has not provided any good guidelines so I was just hoping if you guys could check my work before I move on to step 2 and let me know if I'm correct ...
100 views

### Diodes circuit confusion

If we have this circuit: The diode with the lowest forward voltage drop will conduct and turn on while the other will turn off and not conduct current. If I have this circuit: Assuming the 2 diodes ...
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### Understanding specifications

I have a differential signal which I want to measure with a differential probe. While reading the specification of the probe, I got confused with a few terms. Can someone what the highlighted terms ...
49 views

### Zener diode simulation issue

I have this simulation issue and I don't know how to solve it: The Zener current is smaller than the breakdown current yet the Zener diode still acts like a voltage regulator. Any help? Shouldn't the ...
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### What are these on the probes

I am having a Lecroy differential probe and trying to measure a LVDS signal. This is the Reference Manual which I am referring to as a guide. My differential probe tip/lead model number : DX20 - SP/SI/...
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### How does mouse keep working when the battery is drained?

When battery is drained with time it provides less voltage. Which makes me wonder - how does appliance (like a mouse) keeps working with lower voltage? Is it because electrical components inside can ...
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### phase between the input voltage and the output voltage?

If I have this circuit, how can I calculate the phase between the input voltage and the output voltage (capacitor voltage)? Knowing that the signal frequency is 1kHz
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### Detecting a parasitic voltage/current that differs from line frequency

I have a question related to electronics: "Someone told you that there might be a problem with the electrical circuit: In addition to the standard 50Hz alternative voltage, it mights exist ...
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### Current to voltage circuit

I'm currently doing a project that consists of testing bio-implants to see if they are still good to use. For this, I have to measure the impedance of the implant from frequency starting at 10Hz to ...
115 views

### Voltage regulator output too high

I'm trying to provide a 3.3V source for my micro controller from a 5V power supply, however seem to be having issues with all the 3.3V regulators I've tried. I'm currently trying to use an MT1117-3.3, ...
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### Maximum voltage divider resistances for sensing LiPo battery voltage over 10bit ADC: is MOhm range working?

I've designed a PCB that should contain as few components as possible but it should have a simple way for measuring the battery voltage using an ADC channel and a simple voltage divider. My current ...
56 views

### Rear light on vintage motorcycle 6 V split to 5 V

I have a 6 volt vintage motorcycle. With it being a 1920s motorbike, there was no need for a brake light to be attached/fitted by law just a rear light. However I am not comfortable with this and I ...
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### What keeps voltage/current/power from flowing into “branch two” from the “Vout” node in the below drawing?

I need Vin to go into one of two branches and then continue to Vout, the boxes represent DC-DC converter, one at 20V and another at 15V. What keeps voltage from going through Branch 1 into Vout node ...