Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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).

0
votes
0answers
51 views

How to choose resistors for a multiple resistor voltage divider circuit?

I am trying to create a voltage divider circuit to off offsset two BJT input voltage is for a push pull amplifier configuration, and I am having trouble choosing the proper resistor values for my ...
1
vote
1answer
38 views

How do I find the Thevenin voltage and resistance equations of this circuit?

How do I find the Thevenin voltage and resistance equations of this circuit, with respect to the terminals U and G when Rc, Vc, Rt, and Rtrans are given?
0
votes
1answer
61 views

What is the current draw of a capacitor in a VOLTAGE BOOSTER

I'm trying to learn by myself the principles of a voltage boost converter. **BATTERY IS 1.2v@4300mAh I noticed that many sources* suggest not putting a resistor in series with the capacitor (as in ...
0
votes
1answer
59 views

Realise circuit for hFe measurement

To measure Beta (hFe) of the transistor you should zero u_ce (voltage across CE for the AC component in signal). To zero that component you put capacitor in parallel with transistor AND as shown on ...
0
votes
2answers
68 views

How to determine the correct polarity of the diode

I'm having trouble knowing when is the cathode negative or positive and vice verse ( I'm not talking about the symbol ) I'm saying, when do the polarities change? For example, look at these 2 pictures ...
1
vote
1answer
23 views

Vdc in ripple factor

V_p(rect) is the rectified unfiltered peak voltage V_r(pp) is the peak-to-peak voltage after filtering by a capacitor Here is a picture: V_r(pp) is given by the expression: Which I have no problem ...
0
votes
3answers
45 views

Resistor in series needed with LED string?

I have an adjustable 24VDC power supply. I have 1W LEDs that I was planning on stringing 7 or 8 in series to get approximately 24V across all of them together. They are rated 3.3-3.8V each. Do I need ...
2
votes
1answer
60 views

Relay - must drop-out voltage

simulate this circuit – Schematic created using CircuitLab I have an output that can operate a relay at 12V but the drop out voltage is 6V. So the relay never drops out once pulled in at 12V, ...
0
votes
0answers
31 views

Inductor fallback

What happens if I have a circuit with 3 volt battery and 10mH inductor. Circuit is closed and I open it when current through inductor is 600mA. Will there always be a spark, Why ?Article
0
votes
4answers
132 views

What will happen if I use laptop charger (3.42A, 19.2V) to charge 12V battery? [closed]

The battery's voltage normally is 13.8V when it fully charged. Say I have 5.7Ah motor bike's battery. The laptop's charger will be connected to a battery. The positive port of the charger to positive ...
2
votes
2answers
73 views

Read voltage of the battery that feeds ATmega328p

I am designing a system focused on the uC ATmega328p and I am feeding it directly with a 3.7V LiPo battery. I also have a 3.3V LDO feeding several sensors in the system. My question is the next, If I ...
0
votes
0answers
39 views

Simplest way charge a 3.3V capacitor off of a 9V battery

If we have a series RC circuit in this case, the voltage across the capacitor will exceed 3.3V as the current decreases, no matter what the resistance is, right? This will blow the cap... So what ...
0
votes
3answers
113 views

Is high current in a speaker the same as high voltage?

I'd like to build my own Amplifier, and because I know that the current creates the magnetic field, I don't understand, how amplifying the voltage makes it louder. I mean with high voltage doesn't ...
0
votes
1answer
51 views

MCP73871 Battery Under Voltage Protection

I want to use MCP73871. Is there a battery under voltage protection in this charger IC? or may I use a battery protection IC? Answer for @Bimpelrekkie I decide to use my power architecture as ...
0
votes
1answer
61 views

LTC3106 - getting 3.26v instead of 3.3v

We designed a power supply for an iOT. The uses SoCl2 battery and solar panel combination. The circuit is functioning and we are getting 3.26v consistently for over 3 days now. LTC3106 is configured ...
0
votes
2answers
36 views

Using a 10V stepper motor with a 12V controller board

What should I do when using a 10V .5A NEMA14 stepper motor with this board: https://reprap.org/wiki/MiniRambo (beyond setting proper current limits in firmware)? If I understand it correctly, the ...
0
votes
1answer
35 views

Use of large motor capacitors to stop voltage drops from because of high electrical draws

Good Day Everyone. Please bear with me and have patience. I have a feeling I will quickly be considered the village idiot here. I have trouble with voltage fluctuation especially with high demand ...
0
votes
1answer
103 views

Is this DIY high voltage AC generator safe to use?

Making a DIY type high voltage AC power supply from 40 W soldering iron, 220 V AC to 12 or 6 V AC step down transformer and 5 A fuse. These things are ALL connected in series to the 220 V AC mains. ...
4
votes
1answer
350 views

Feedback in LM2574

I wonder what is the purpose of 'R66' at the feedback terminal of LM2574? I have seen its datasheet but I cannot find info about this. Instead of a single resistor there is a voltage divider shown in ...
0
votes
2answers
66 views

High voltage drop when load is connected [closed]

I'm getting 6 volts open circuit voltage. Whenever I connect a load (resistors), there is a huge drop in voltage values. Does it signify power input is less or is there any other reason for the same? ...
0
votes
2answers
67 views

How do I convert the units of a moving magnetic field to volts?

Copper wire wrapped around an iron core produces current when a strong magnet is moved in its vicinity. I gather the "magnet movement" part is expressed in units of "weber" (kg⋅m2⋅s−2⋅A−1) or perhaps ...
2
votes
1answer
124 views

Generator Dropping characteristics

I was studying about Droop characteristics. I came across the following flow path for a thermal plant Plant is working at 130MW and 50Hz Due to some load increase, frequency of the grid drops say 49....
1
vote
2answers
141 views

What does 9 V mean in 9 V motor?

Does it mean that you need 9 V to make the motor start, or is this the max voltage before it is damaged?
3
votes
5answers
107 views

Diode and resistor series

Can someone show me how to calculate voltage drops and current on this circuit? simulate this circuit – Schematic created using CircuitLab I have 9 V source and 100 Ohm resistor. So for the ...
0
votes
2answers
27 views

Thresholds in Static discipline

The Voltage thresholds \$V_{OH},\ V_{OL},\ V_{IH},\ V_{IL}\$ as far as I understood, they represent, \$ V_{OH}\$ ~ The sender must produce a voltage above \$ V_{OH}\$ for sending a \$1\$ \$ V_{OL}\$...
1
vote
2answers
67 views

Plot voltage for different resistor values in LTSpice

I've signed up for a SPICE course at work, that will take place on Monday and I'm desperately trying to learn electronics and SPICE. (I work as an embedded engineer but with very lacking electronics ...
1
vote
3answers
79 views

How can I calculate voltage drop on non resistors?

I understand that calculating voltage drop with two or more resistors in series is easy because we can apply ohms law and divide up the supply voltage relative to the resistance of each individual ...
2
votes
5answers
449 views

Cheap 12V to 5V DC-DC converter for PCB? [closed]

I want to clarify: I understand there have been many questions on this site regarding this same voltage conversion; however, what I am asking is not simply how to convert 12V to 5V but how to do it in ...
1
vote
5answers
71 views

When charging rechargable battery, should we care about watts and ignore voltage and current?

I know this might be a silly question, but it's from a beginner. Let's say I want to charge a rechargable lithium-ion battery, so when I charge it should I only check the watts and ignore voltage and ...
1
vote
2answers
41 views

Driving Avalanche Photodiodes (PCBs)

I am using Avalanche Photodiodes and I was told that they use a much higher voltage then standard photodiodes and I was wondering if I need a High Voltage PCB to drive them? I am currently just using ...
2
votes
1answer
102 views

X5R capacitor derating and highpass filters

X5R capacitors derate to about roughly 85% when DC voltage is applied, from what I have been told. Does this have an effect on high pass filters, even though HF filters off DC (0Hz)? If I wanted to ...
0
votes
0answers
36 views

Finding the voltage of base Vb

I wanted to know if Vb in the trasistor in the photo is equal to the formula in red circle: Vb=R2*Vcc/(R1+R2)
0
votes
2answers
77 views

Tape recorder with live chassis [closed]

I am trying to repair a Revox B77. The issue is that the whole machine is live. I am looking to know if the issue is with the voltage selector or even some guidance as a starting place where to look ...
0
votes
1answer
69 views

12V DC voltage drop for second switch 10 meters away

I have a ground floor main door lock operated by a solenoid (12W, 12 V), the switch (push button) of which is located at first floor, the power to this switch is given by an AC to DC(12V) adaptor - ...
1
vote
1answer
41 views

What would cause a voltage rail to be held low without measuring a short circuit?

I have a circuit that provides power (1.8VD) to an FPGA and some ADCs. I have seen in the past where damage (ESD, EOS, etc) occurs to one of the ADCs. This causes a short from 1.8VD to GND internal to ...
1
vote
1answer
51 views

Suitable NMOS with 3.3V gate voltage to switch 12V 500mA

I've got a circuit board with a D2PAK NMOS pad that I need to find a mosfet that will work with a raspberry pi's 3.3V GPIO. This is the current one I'm using and it isn't working well. https://www....
1
vote
2answers
53 views

what limits the maximum voltage of this optocoupler (6N137)?

In the datasheet it is stated that the maximum VCC voltage is +5.5V.(https://www.vishay.com/docs/84732/6n137.pdf) Because ive been told to question everything (and i have enought of them to kill one ...
-1
votes
3answers
75 views

How can I increase the AMPs in a transformer less power supply

I am very new to electronics and trying to do something which I am not much aware of yet. I have a NodeMCU (based on esp8266) for which I need power supply of 5V and it required I guess more then ...
0
votes
1answer
56 views

Random Noise Voltage

I have a signal I am interested in obtaining power from. The best way to describe the signal is that it is random. In the graph, the voltage fluctuates from negative to positive with an RMS of 0.5 ...
1
vote
2answers
115 views

Battery failing. Oscilloscope?

The question is - is there an inexpensive oscilloscope I can use to measure DC voltage and current to see why my battery pack is failing to power a DSLR? In order to take long time lapse photos with ...
0
votes
2answers
87 views

Sharing a USB keyboard between two PCs on a button flip

The PCB for the task would comprise of a USB connector, two sets of 4 PTH for the two USB cables (one set towards PC 1, the other towards PC 2), shared GND and TX and a DPDT switch for separating the ...
2
votes
2answers
96 views

Powering a 3 Phase 230VAC Motor with 28 12V Batteries wired in Series

Mechanical Engineering student here. I'm a part of a senior project team that trying to run a 40 HP 230 VAC three phase motor with a 40 HP VFD for a hydraulic pump. Our plan is to wire 28 Lead Acid ...
0
votes
1answer
52 views

5 V and Ground Reverse direction

I have a circuit drawing like below image. I need to replace a connector, but when I checked the connection is different compare to the original drawing. (New connection indicated by red color) 1) ...
3
votes
4answers
222 views

What types of mechanical switches are appropriate for a 200 V DC 20 mA circuit

I have looked at many switches, most recently I considered snap action switches (micro switches). What I prefer to use is a PCB mounted switch, but I cannot find any that can tolerate the V DC ratings ...
2
votes
0answers
78 views

Way to power a monitor that requires 12 V 2.5 amps with a PC USB port [closed]

I am looking to see if there is a way to power a monitor like this: (https://www.amazon.com/gp/product/B07774L6TT/ref=ask_ql_qh_dp_hza) over one (or two) of the PC's USB ports, so theoretically it ...
0
votes
2answers
57 views

Can I run DC voltage through RJ45 Connector with Magnetics?

I am designing a PoE (Power over Ethernet) application. My question is can I run 48V DC Voltage through a standard RJ45 Jack WITH Magnetics? or do I need one WITHOUT magnetics? I am planning to use ...
18
votes
1answer
3k views

How much time does it take for a switch to go from on to off?

The equation for the voltage across an inductor is v = L di/dt. When a switch changes the circuit from closed to open, it changes the current very quickly. My question is how would one know exactly ...
0
votes
1answer
38 views

What does this bidirectional TVS diode do

This is a schematic for a crude taser design ive been studying. From what i can tell when the switch is on the relay turns on and off continuously, which charges up the LC circuit in which the ...
0
votes
0answers
32 views

Calculating voltage loss using impedance of a system

simulate this circuit – Schematic created using CircuitLab So I'm trying to figure out the Total impedance Z of a system with a capacitor in series with a resistor and inductor, where the ...
0
votes
1answer
22 views

Maximum Vin on load switch ICs

I'm trying to determine whether the absolute maximum rating for Vin on load switch ICs applies for when the switch is both open and closed. When the switch is closed, it makes absolute sense to me ...