DC stands for Direct Current, which means the flow of electric charge in a single direction. Examples of a DC source are batteries, solar panels, dynamos.

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How to implement an adjustable DC offset removal with single supply?

I want to make a circuit where I receive very weak badly shaped constant frequency pulses with DC offsets and obtain an ultimate output with adjustable pulse amplitudes, and with adjustable dc offset ...
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29 views

How to implement a variable offset voltage in a single supply non-inverting Op-amp? [duplicate]

I want to add or remove some DC offset from the output of single supply non-inverting Op-amp. When I connect the inverting input to a voltage source(instead of GND) lets say V volts, the output has -V ...
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1answer
53 views

How do I build a DC time out circuit that stays off until power is toggled?

My girlfriend bought an LED faucet that is actuated when you turn the water on and is powered by a battery pack of 4 AA batteries (2 wire out). However, when the water is turned off, the slope of ...
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3answers
975 views

Can a diode effectively regulate a supply voltage?

I have a 6V DC battery that's rated at 2A. My microcontroller uses 5V supply at about 50 mA. I've been told I shouldn't worry about the current since the microcontroller will just take what it needs. ...
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1answer
56 views

Possible to take 110 down to safe level to run LEDs?

I'm working on a lamp project that I found online. It's a DIY lamp with a whiskey bottle for the base. The project itself just uses a standard 110V plug that goes right in to the wall, but I wanted to ...
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1answer
57 views

Transformerless rectification is giving out AC component [duplicate]

I want to convert 240V AC 50hz to 12V DC without transformer.I want the output (12V) to drive 25 white LEDs.The circuit is giving an output of ~14V DC.But the problem is that it is also giving out ...
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34 views

DC Motor Speed Control With 555

Can you please explain why this circut is not working in simulation. I get GMIN Stepping failed, too many iterations errors. Is there something wrong with the design?
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2answers
59 views

N-Channel MOSFET as 12 VDC switch

A little background: I have a 12 VDC "cigarette" socket in my car which is a non-switched circuit (so, always on). I'm in need of a switched socket, whereby power is cut when the car is not running. ...
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1answer
38 views

Is Deuterium arc lamp a AC or DC light source?

I have created a prototype photo-detector circuit to use in spectroscopy. The micro-controller code take 120 A/D readings and then returns average. I have noticed that when I use visible light ...
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0answers
20 views

Is the armature resistance of a DC motor the sum of the resistance of each winding?

I am aware of a number of methods of measuring the armature resistance of a DC motor including locking the rotor, giving a fraction of the rated voltage, measuring the current and calculating the ...
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2answers
20 views

Frequency design parameter for DC signals

I have been using some online tools to design a circuit to amplify photo-diode current. I have understood that all such tools needs a frequency/bandwidth to drive the calculations. For example, a Low ...
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1answer
42 views

Replacing a Piezo with a button

In my senior engineering design class for high school, my teacher bought a toaster oven and microcontroller and tasked my group to make surface mount digital dice kit for him to teach surface mount ...
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1answer
49 views

How to supply 5 to 12v amplifier LM386

I started electronics recently and I'm trying to make the most basic mp3 amplifier. First I tried to make the amp myself with reused electronic parts but I didn't succeed... Amplify speaker with 9v ...
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1answer
75 views

Non-zero output from a LM741 in a differential configuration

I'm trying to amplify a DC voltage coming from a strain cell (with a built in Wheatstone bridge). The voltage swings from -1mV to about 4mV depending on the strain. I've set up a differential ...
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6answers
85 views

Frequency DC voltage

Maybe it is a silly question, but a microcontroller it is powered up with a voltage of 3.3 DC voltage, and we all know that the frequency of the DC voltage is 0 Hz. Suppose that i want to generate a ...
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1answer
49 views

Is there any way to use an ac load ssr with a dc load

i have a s202s01 relay that i want to connect to my microcontroller. The problem is that the load i want to control is a DC source. Is there any way to make that ssr (3-24dc, 8A 250VAC) work with a ...
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1answer
45 views

voltage range of ac signal

I have an ac signal in the range of 1.5v-10v and it needs to be shifted down by 0.5v so it is in the range of 1v-9.5v. How can i do this exactly? assuming it uses a single power supply. any help ...
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1answer
45 views

Combining 2 or more DC sources

This is a fairly general question with no specific example in mind as I was just thinking about the problem, but was unable to find any answers on the internet (probably because I am not asking the ...
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0answers
18 views

lmd18245 dc motor driver

How to build dc motor driver lmd18245t. wanna control dc motor with arduino uno by pwm signal so how make driver circuit using lmd18245t ic and in pic. i made circuit schematic is this correct or any ...
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1answer
47 views

Powering 3 DC devices from one outlet

I have be trying to research how I would go about powering 3 Raspberry Pi devices using only 1 outlet. The raspberry pi require 5v and a max of 2a. I think I know just enough about electronics in ...
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5answers
601 views

Using DC current to operate a fish feeder that takes 2 AA batteries [duplicate]

I'm a complete electronics newbie. I have a auto fish feeder that takes 2 AA (1.5V) batteries. After changing the batteries quite often I got curious to find out if the feeder can be modified to run ...
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0answers
174 views

Circuit Q - Calculating the minimum internal resistance for max 2% voltage error

I am stuck with this question. Not very confident with my approach. In the circuit below: Question reads: "Assuming you have a real voltmeter with non-infinite internal resistance and that you ...
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6answers
186 views

Why does electricity have a phase?

Anyone who's seen the j in electrical formulas knows that electricity has a phase component as well as a magnitude. But where does the phase come from? Does it only ...
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2answers
46 views

DC analysis of common source MOSFET circuits to find gate voltage using different power supplies

simulate this circuit – Schematic created using CircuitLab strong text I am solving problems on DC analysis of MOSFET circuits. We are supposed to find various parameters like Id(Drain ...
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3answers
123 views

Why don't DC PSUs need a fuse?

This feels like a silly question, but after taking apart some of our 6W 12V DC power supplies I've noticed that none of them are fused. Out of curiosity more than anything else, I'm wondering why a ...
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0answers
47 views

Inverter vs Rotating Machine

My question is in how to relate a 3 phase PV inverter to a classical rotating machine. How is the machines power angle realized by the inverter? In power flow studies, real power flows by ...
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2answers
97 views

Need help with a VU meter analog signal

I am making an Arduino VU meter. I need to convert an analog AC audio signal to a varying positive DC signal. I would like the following outputs: 2.5 V output at 0 V input (from VM1); 5 V at maximum ...
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1answer
38 views

please help me choose power mosfet for multilevel inverter

I am doing my senior project on cascaded multilevel inverter. I am planning to use MOSFETs as switches in my project.Please kindly give me instructions and respective formulas for getting right ...
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1answer
63 views

Make a brushed DC motor move “free”

I want to place a DC motor on the driveshaft of a marine steam engine. Since i do not want to loose or add power to the drive but only having the motor there for backup reasons, i want to let the DC ...
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1answer
29 views

reverse load on dc motor( series/shunt) and its speed control

if dc motor produces 10 Nm torque , and load acting on dc motor in reverse direction produces 6 Nm , then net torque is 10-6= 4Nm, dc motor consumes current corresponding to 4Nm , and so speed becomes ...
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0answers
58 views

Reverse engineering MOSFET power circuit

I'm looking at a portable heater circuit that uses a 1.4 Ohm resistive load as the heating element. The circuit in question uses an N-channel dual output mosfet, and on the other side of the board a ...
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3answers
53 views

Switch current rating AC vs DC

I'm looking for a high current DC switch (able to switch something like 5V@30A) and I've encountered several DPDT that might do what I need, however they are only rated for AC applications (3A@250VAC ...
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3answers
74 views

Controlling audio singal with digital potentiometer?

I am very confused about how to go about using my digital potentiometer to control an audio signal. I have a MCP4231 digital pot and would like to use it as a MCU controlled variable resistor for gain ...
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1answer
150 views

Dangerous Power Supply [closed]

I recently bought a 3D printer from the USA and imported it to the UK, it came with a Chinese 12v DC 30 Amp power regulator. The PSU is a metal enclosed box. It can take 220 Volts +/-15% so it should ...
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2answers
57 views

how to compensate power drains in dc circuits?

This has been on my mind for a while. Lets just take any electronics device. Lets say a mobile phone or a laptop. They have fixed voltage and current, but some components needs higher voltage/current ...
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1answer
48 views

Low Breakover Voltage Diac [closed]

I wanted to know if there is commercially available Diacs with Breakover Voltage of 20V or less. I tried to find in the internet but always ending up to Diacs with Breakover Voltage of around 30V or ...
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1answer
47 views

Cable parameters calculation for a long 1000 V DC cable

How to calculate the current that is needed to charge the cable capacitance and inductance while switching DC power supply ON? And the current that is released from the cable inductance and ...
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1answer
50 views

Shared Voltmeter for 2 DC Circuits at Different Voltages (battery & solar)

I want to use one panel mount voltmeter (Powerwerx PanelDVM) for measuring both my 12VDC Battery output and the input voltage from a Solar panel ,which has a higher DC Voltage. This all is hooked to a ...
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3answers
67 views

bulbs in series with individual power [closed]

Three lamps (with individual power of 30W , 40W and 50W ) are connected in series to a source of 100V . What is the voltage to the terminals of the 40W lamp ?
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2answers
127 views

How does a bridge rectifier work exactly?

If this question was posted before, please let me know. I searched for "how does a bridge rectifier work" and did not find an answer. The part that I especially find confusing is when I have the ...
3
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1answer
49 views

Circuits problem

simulate this circuit – Schematic created using CircuitLab My question is what's the voltage between C and D? R7=1kΩ Vc-Vd = (Vc-Vb)/1000 + (Vb-Va)/1000 + (Va-Vd)/1000 = ...
5
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2answers
111 views

How do I combine multiple A/C and D/C power sources into one electrical system? [closed]

I'm looking to design an off-grid power system for my house. I'm a complete novice at this point but I'm willing to do a lot of reading to complete the project. There is a lot I still don't yet know ...
2
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1answer
61 views

should I use high voltage or high current to burn carbon rods to dust

I want to burn carbon rods in a vacuum chamber to coat samples in carbon and need the carbon rods to be completely evaporated (worn out /eroded) through electrical power. I also need the +ve ...
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2answers
75 views

Can pulsating DC be used for induction heating?

I want to make an induction heater work using a 12 v, 35 A-h battery(used in cars). I don't want to use an inverter. Will a pulsating DC input to the induction heater make it work?
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2answers
58 views

Create a Time-Variable Dc Power Source

For some reason, I need a Time-Variable DC power source that changes it's value according to time. I need this changing of value to be controllable. I'll put it this way : Say I have a 12 volt DC ...
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3answers
112 views

Why does a simple circuit drain a battery slowly?

OK, so if you directly connect the two terminals of a battery, there is very little resistance in the circuit and you will drain the battery very quickly. However if you have a very simple circuit, ...
3
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1answer
41 views

How to select a DC cable connection type based on current?

I have a battery and DC-DC converter solution that I've ordered. The solution will output 20A continuously at 5V, and will sometimes pulse up to 30A for durations up to 10 seconds. I believe voltage ...
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3answers
63 views

Are DC induction motors possible?

Forgive me if I am asking something absurd, I really do not understand much about electric motors. After reading the answers of Why does a Tesla car use an AC motor instead of a DC one? , I got ...
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3answers
115 views

How to analyze this Diode Circuit by hand?

I need to analyze this circuit by hand, I'm a Mechanical Engineer, so I really have no idea what I'm doing here. I thought about doing the parallel of the 2 top resistances and same for the bottom ...
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2answers
60 views

Powering a rpi and accessory of a 9v battery [closed]

We are trying to use a raspberry pi to record the current going through a dc circuit. The circuit we are trying to measure the current in is powered by a car battery. We have no idea how to record the ...