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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48 views

how many volts will it take to run a 12 volt motor

I am attempting to repair a lemax Halloween decoration for my wife. The power adapter says 9 v output but there are 2 motors inside the decoration that shows 12 v. Does this mean the adapter is rated ...
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1answer
34 views

12V fans in series with 25 A supply

I'm trying to set up a relayed cooling mechanism for a mass spectrometer (i.e. cooling fans turn on when the MS exceeds a certain temperature). I have a 24V DC/25A power supply which converts 100-120V ...
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0answers
45 views

Series/Parallel configuration?

If I had a large bus bar, then split it into to pieces, and in between I connected them via separate wires that have their own insulation depicted in this simple diagram: At point A it shows the ...
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1answer
39 views

Powering a Futaba S3003 servo

I'm working on a project and I need to use a Futaba S3003 servo, I'm about to buy a transformer that gives 6v, the thing I'm not sure about is the amperage. Is this transformer ok? I can choose 3V, ...
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2answers
43 views

How to calibrate an ammeter and voltmeter?

How can I calibrate an ammeter and a voltmeter. I just want to know about it. Because it might be helpful and I think it is a vital thing to know. So how can I do this?
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0answers
57 views

Reusing a old non perfectly regulated 12v powersupply

12 volt power supply shows 16.8 volt Not long time ago i made a simple low voltage rgb pwm circuit to test with raspberry and arduino. Now after a while of reusing old chagers and recycled ...
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1answer
78 views

Do AC voltages on datasheets refer to peak voltage or Vrms?

I'm attempting to find a relay to switch UK mains voltage (230Vrms); this gives a peak range of approximately 325V, -325V. Consider something such as the datasheet for this relay. It has a ...
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1answer
44 views

Voltage measurement

With the 100ohm resistor sitting between my 12V power supply and my device it doesn't spin (it's a hard disk). I also tried to measure the voltage drop with a multimeter to no avail. It always shows ...
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4answers
929 views

Checking when a car horn is pressed?

I want to detect when a car horn is pressed. The only way I can detect it currently is using the voltage on its line. When the car is turned on, there is always 12V being supplied to the horn through ...
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0answers
46 views

Distortion in an amplifier

I need help with this exercise: "Given a common-source amplifier without any charge, it can be seen that there's cut-off distortion. How can you fix that, without changing the gain of the amplifier?" ...
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0answers
39 views

JFET - Pinch off voltage value

I have a JFET channel N and I have N_A, N_D, V_TH and the width of the channel without any bias voltage applied. I need to know the cut-off voltage. The cut-off voltage is the pinch-off voltage, ...
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1answer
53 views

is this possible: Amps feed joining a Regulated V line

As we all know linear regulators cannot handle a lot of amperage and tend to waste a lot of energy, so I was thinking if it is possible to create a regulated output then put the amperage after the ...
2
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2answers
422 views

transformer has continuity but no voltage output?

I have two old transformers that appear to be fine, however no DC voltage was measured on the secondary coil. I have measured: The input voltage: 229 AC the input coil ohms: 0.015 kOhms the two ...
2
votes
4answers
75 views

Moving two elements from series to parallel

I got a small pizza oven with two elements (top and bottom), they are rated 115V 600W and they are connected in series, as we have 230V in Europe. Everything works fine, but I would like to control ...
0
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1answer
37 views

Confusing transformer winding, what is it and can i change it?

here are two 380V to 24V/48v transformers that weigh 10 pounds each. I was hoping i could get 15V with 500w out of one at 240V and measure the welding potential. the secondary winding uses 0.5mm ...
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2answers
263 views

Measuring current drops voltage?

We have some pcb in which contains an MCU ,and some WiFi module . Usually at start, the board takes 70-100mA with 3v3 . It gets its current from the UNO board connected to a mac. It works great like ...
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1answer
22 views

Large voltage/amperage battery issues

I have purchased this lithium polymer battery (11.1V, 5500mAh), to power a robotics project. The project uses a Raspberry Pi, three continuous-rotation servo motors, a couple of LEDs and a Sparkfun ...
0
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1answer
106 views

dropping 24v to 12v simply and efficiently

I have a 24v solar system, and I want to get only 12v from the DC output Currently I am taking a wire from only 1 battery, but this causes unbalance in the batteries and I have to check it a lot and ...
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6answers
2k views

How can voltage burn out an LED?

I understand how a current higher than what the LED is rated for can burn out an LED, but how does something equivalent happen with voltage? If the correct current is on an LED but the voltage is too ...
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1answer
47 views

Common-Drain Amplifer vs OP-Amp for unity gain (voltage Follower)

What is the difference between using a nFET vs OP-Amp as a unity gain amplifier, i.e. voltage follower. Application: Provide constant voltage with a variable load, see example below: Min Current ...
3
votes
1answer
170 views

Achieving (near) exact voltage divider ratio

Often, I'll have a need to create a voltage divider that has a specific resistance ratio, to obtain whatever voltage I need on the output. For example, for a specific project I'm working on (creating ...
2
votes
1answer
63 views

How to make arduino GPIO to operate at 3.3v instead of default 5v

I am working on a project, I use arduino mega 2560 with system operating voltage of 5v, at the same time I have a Bluetooth module which operates at 3.3v is there any way to reduce my arduino output ...
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3answers
74 views

How do I know current across unknown load if I know voltage

If I know voltage across a load, but don't know load resistance, how do I know current going through load? Do I put a resistor of 1K and calculate? My voltage is square wave so multimeter only get ...
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0answers
57 views

circuit help voltage multiplier

Hello I am using a breadboard and I created the circuit below. I am using Two buttons to gain and fade a voltage output. I am using a voltage multiplier because my source is only 5 volts and I want ...
2
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0answers
45 views

node voltage conflict

background: My goal is to use an Arduino with two proximity probe (sensors) to achieve some output. It is worth mentioning that the output of the proximity probe has two components: DC output that ...
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1answer
58 views

What does 125VAC mean on a small indicator bulb?

I have recently discovered a small box device that used to have an indicator bulb on it that would switch on when a switch was flicked. I am not sure what voltage to give the bulb, or if its AC or DC, ...
6
votes
1answer
183 views

Trouble getting 555 timer IC circuit to work properly (Make Electronics Book Experiment 18)

I am currently reading a book titled “Make: Electronics”. This is an electronics book whose target audience is supposed to be complete beginners. One of the book exercises (Experiment 18) includes a ...
2
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2answers
119 views

How to adjust linear voltage regulator equivalent?

I'm attempting to build a linear voltage supply. (I'm not touching the mains yet.) My first thought was to use an adjustable linear voltage regulator. Unfortunately, I found that linear voltage ...
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2answers
61 views

Internal reference of MCU

The internal reference of the MCU is 1.45 V. I am relying on this to measure ambient temperature ratio-metrically using NTC and a resistor. The MCU datasheet says that the internal voltage reference ...
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1answer
117 views

LED indicator for DC voltage

I am planning to using a buck / boost converter to run a DSLR camera from my USB powerbank AND other power sources. For that module I want to build with the buck / boost converter, I need a simple LED ...
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3answers
133 views

BJT Circuit Base-Emmitter voltage

I don't understand, why the voltage V2 is approximately Vb. Can't V2 be 0, if Vb is enough high, so that the emmiter-current of Q2 is Ie2? The assistent only told me, that because both transistors ...
0
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1answer
45 views

How lightning arrestors are usefull? [closed]

What is a lightning arrestor? How they work? And where we have to use this in our electrical power system? I think i have saw this at the output of transformer. And also i have notice that, even ...
1
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3answers
72 views

Can I use a voltage divider and a multiplier to power a 12V component from a 5V supply?

My idea was to use a the two points in a voltage divider circuit (5V and let's say 2.4V), feed those through a multiplier to power a 12V component. Is this possible? Any problems that may be ...
1
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0answers
98 views

Buy amplifier to amplify analog 0-5V signal to 0-10V [closed]

I realise the title question has already been answered here in one way or another: Amplify 0 - 3.3V DAC signal to 0 - 10V and Scale 30-50mv signal to 0-5v range I don't understand electronics very ...
3
votes
1answer
44 views

How can you build a floating two-port VCVS?

I have a control voltage at one point in a circuit which I need to duplicate at various other points (3 or 4, if I remember correctly). I'd like to use one potentiometer to control these voltages, so ...
1
vote
2answers
65 views

DC motor as rotational speed sensor?

Will spinning a small DC motor work effectively as a rotational speed sensor (by producing voltage)? I'm trying to measure the rotation of a shaft (driven by a trackball) on a shoestring budget. I ...
0
votes
1answer
78 views

Circuit help. I want a Voltage gain from 5 volts to 10 volts.

I need some circuit help.. I am trying to boost my voltage from a 5v source to a 10v output so I want a Gain of 2. I Ran the simulation and built the circuit exactly how it is shown in the figure ...
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2answers
61 views

Will changing my capacitors for ones with higher voltage but same microfarad allow me to use higher voltage batteries

I have a r/c car that I'd like to use 8 of the 3.2v AA batteries instead of the typical 8 1.2v AA. There are two capacitors one is 2200uf 10v the other is 220uf 16v, if i replace them with 35v of the ...
1
vote
2answers
28 views

RC circuit with lossy capacitor

This circuit simulate this circuit – Schematic created using CircuitLab can be regarded as an RC series circuit with a lossy capacitor. The time expression for \$V_C(t)\$ with \$R_2 \to ...
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2answers
61 views

How to calculate the voltage across the load of this circuit

I have this rechargeable night lamp which I built it using the circuit which I got it over the internet.There is no problem with the night lamp but I just wanted study the working of the circuit but I ...
0
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1answer
43 views

Combining two different voltages into one regulated voltage at higher amperage

The Commodore 64 user port has a +5V supply at 100mA and a 9VAC supply also at 100mA. I need about 150mA from the port at 3.3 volts. Is there a way I can use both supplies to get the amperage I ...
0
votes
1answer
38 views

Different voltages and amp draw

This is probably a basic electronics question, but I'm a self-taught hobbyist and I can't seem to find a direct answer to this. I have a host device that I want to connect to that supplies 100mA at ...
0
votes
3answers
75 views

Can (or should) two voltage regulators be connected in a parallel configuration. [duplicate]

I have two 5 volt voltage regulators that I would like to connect to a 9 volt source in a parallel configuration. Is this advisable, problematic, or even commonly done? I have tested this ...
4
votes
2answers
474 views

Why does measuring the voltage drop across a thing not simply measure the battery voltage?

Imagine a trivial circuit with battery and one resistor. To measure the "voltage drop" across the resistor, we stick a voltmeter in parallel with it. However, this means the voltmeter is also directly ...
0
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1answer
50 views

question about charge pump circuit

My charge pump circuit is giving increased Vload in simulator, about 22v. but when I breadboard and test, with Vsupply from a 12V power supply, multimeter shows Vload about 11v. I've tested changing ...
0
votes
2answers
48 views

Confusing relay rating [closed]

I have this relay and the ratings are quite confusing - 10A 30v and 10A 28v, I'm confused as to why there are two. Could anyone please explain it to me. Thank you
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0answers
42 views

High pass filter DC blocking equations

Given a 12 volt DC supply to a potential divider circuit and a coupling capacitor connected to a 40 mVp AC, how would I confirm that the resistance between ground and capacitor is low or high enough ...
1
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1answer
65 views

calculate Amp Hours when voltage is given

I'm trying to wrap my head around how exactly Amp Hours work. I have been trying to figure out this question for a while now, but can't seem to find the information that I need. This is the ...
0
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0answers
43 views

Whats the KVL equation for this circuit?

Here is what I calculated but I'm not sure: $$-10 + 5*I2 - 2*I1 + 1*I4 + 5 - 3*I3 - 4*I3 = 0$$
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0answers
25 views

2 - 12 volt power sources into [migrated]

How can I power one 12 volt outlet (feeding a xm radio transformer) from 2 - 12 volts sources on a RV (ignition and coach power). Is it feasible to use 2 diodes