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 add a DC bias?

I have 70Vrms sine wave, I rectified it with full wave rectifier. So the output is 100Vp.I will divide it down to 1V using voltage divider (0-100V to 0-1V). How could I add a 1.4V DC bias to the ...
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39 views

High Voltage MOSFET Controller - Random Failure

I have a 120V DC Motor that I need to control the speed of. I am doing this through a High Voltage PNP transistor (MJW21193) rated at 250V and 16A with a peak of 30A as I understand it from the data ...
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2answers
64 views

DC non invasive power measurment

For one of my PhD project I have to measure power consumption from different electric wheelchairs during various tasks and recor these measurment for later studies. I have not much experience in ...
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1answer
56 views

Taking an unstable DC voltage, and stabilizing it

I have a DC motor generator (basically the motor spins, and it powers an LED at the moment), and the output current (mAh) and voltage (V) is very unstable. The goal is for the entire circuit to run ...
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30 views

ATX Dell PSU to Offical ATX 2.0 spec pinout [migrated]

Hey all I am using an old Dell Precision R5400 which has the 750w hot swap-able power supply. Problem being, since its a dell, the ATX pin layout is different than that of a normal, standard ATX 2.0 ...
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1answer
40 views

DC motor speed control: 12VDC 700mA fan motor powered by 7.2Ah sealed lead-acid battery

I am using a 7.2 Ampere-hour Sealed Lead Acid Battery to power a 12V DC motor which is driving a fan, and I need to understand ...
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1answer
51 views

floating ground for AC and DC power supplies

I wanted to connect two power supplies, one is AC (240V , 6A) and the other is DC (3,3V, 300mA). But i read in some referrence that connecting AC and DC power supplies could be dangerous if the two ...
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3answers
50 views

Panel mount DC barrel jack on PCB

Is it possible to solder the panel mounted DC connector shown in the image below on to a PCB? I was unable to find an Eagle library for the same. If it is not possible to solder on to a PCB, any ideas ...
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1answer
53 views

Dual Dc regulated voltage circuit design

I'm working on my term project which is designing a dual DC regulated voltage that gives a DC voltage between +or-ve 3 to +or-ve 15. I have completed the testing for positive DC output part, but I ...
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30 views

What polarity is represented by the black with white stripe on DC power cable? [duplicate]

I have a 12V DC adapter that is bricked I want to change it, and I don't know the polarity, this is the photo: What polarity represents the black with white stripe cable?
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1answer
47 views

Transformerless power Supply - 24VDC, 120V AC and 230V AC

I want to know if it is possible to design a power supply for a circuit that can operate from DC and AC using the same input terminals. Thus, the output should be xxV DC (5-24 or whatever is decided ...
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1answer
32 views

no-load DC output voltage of DC wall-wart circuit

I have this question and I believe the answer is 12.73 from the equation V(N) = V(Rated) * sqrt(2). Is this the correct formula and can someone show me how we arrive at it if it is. I am unsure ...
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1answer
48 views

Meaning of AC15, DC1, AC1, and DC13 in relay durability curves

In the datasheet of the relay OMRO G7SA from the durability curve they specify the number of operations as a function of the contact current. Each curve is for a specific current and voltage. The ...
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0answers
29 views

connecting AC signal 250V to DC signal 3V3

I want to measure an AC and DC current about 250V for AC and 3V3 for DC, i want to use an LT1787 (High Side Current Sense Amplifiers) with amplier stage and DSP to acquire the value. The problem is ...
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1answer
43 views

BJT Circuits at DC, base current calculation

I'm trying to walk through the example calculations in the attached example however I cant understand how the author gets the expression for the first step in the process. I tried making up the ...
3
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1answer
140 views

Is there a way of dividing 2 DC voltages? ie Vout = V1/V2

I need to take the ratio of two filter outputs as part of a project. I converted them to DC voltage values using a rectifier and a smoothing capacitor thinking that this would make division easier. ...
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1answer
33 views

Help solving a 2nd-order RLC circuit

This is the practice problem 8.9 of Fundamentals of Electric Circuits 5th Edition. Can someone help me with this question? I need a more detailed solution of this problem. Especially, what are the ...
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0answers
24 views

Mesh analysis confusion — resistor polarity

I used mesh analysis to find Vo in the figure below. However, my set of equations just end up cancelling each other when I do the math. I am also not sure if the polarity of the resistors changes ...
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1answer
38 views

Using an AC speed controllet with an rectifier and dc motor

I salvaged a 12 amp motor from an AC lawnmower and wanted to use a motor controller to reduce the speed. This is the controller I used http://www.amazon.com/gp/aw/d/B00GMBYFRK. The motor is a dc ...
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5answers
644 views

Why pulsed DC passes through a capacitor?

OK, the current flowing through a capacitor equals C*dV/dt, I'm aware of that. What I don't understand is the physics of the process: why does a capacitor pass pulsed DC (0-10V for example) when ...
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1answer
60 views

AC-DC Adaptor flashes on & off

i have bought an ac-dc adaptor to power my mini-water pump. When i give power to the pump it start & goes off immediately and it's repeating like that till i plug it off. Adaptors LED is also ...
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1answer
48 views

How to find places to add power indicator light in simple DC circuits?

I build a lot of little hobby circuits and I usually place them inside of some kind of project box. Right now I'm working on the "Atari Punk Consol" by Forrest Mimms. It looks like this: I tried ...
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1answer
90 views

How design a circuit to control a switch?

I would like to know how I can design a circuit that can control the switch in the diagram below? Output of the circuit should provide TTL operant to open close the switch that control a 12 V DC.
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28 views

Controlling Linear Actuators

I have two 24in linear actuators (http://www.progressiveautomations.com/linear-actuator) that run at different speeds when I connect them in parallel to a 12V battery. How can I get them to run at ...
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2answers
41 views

Problem generating square wave using IC555

I'm having trouble trying to build this circuit: (Step 5) - (diagram below). I built it, and everything works fine, but the coil doesn't spark. I then used a scope-meter to check, and there is a ...
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1answer
48 views

Scale 5-15V to 30-50V using op amp

I have a sensor that output signal values 5-15V. I wish to translate the given signal using op amp to 30-50V. Can u help me with the values of resistors and circuit diagram which shows sensor as well. ...
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57 views

Charge pump configuration

Can anyone please explain the charge pump config. in this circuit. I am having a hard time figuring out what the diodes are used for, and I am not sure I fully understand the caps config. either. ...
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40 views

Circuit Analysis - simplify circuit to calculate current

I have to calculate the current i in this circuit (the values of the resistences are in Siemens, not in Ohms) Using the equivalence between a voltage source in parallel with a resistor with only a ...
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1answer
72 views

Non-inverting op-amp with DC offset

I'm trying to amplify an AC wave (from an audio input) with a maximum amplitude of about 1.8v to a DC oscillation between 0V and 5V with the centre (what would be the zero-crossing on the input) at ...
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1answer
61 views

Is this SSR design recommended?

I want a hard power switch for some battery-powered BLDC motors, but the currents (5A, up to 20A transients) and voltages (up to 60V) limit the kinds of switches I can use. Because I want some small ...
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3answers
116 views

Single-supply DC amplifier circuit with “gain” of 0.66?

I have a DC voltage source \$V_{in}\$ which slowly varies in the range 2.5…4.8V. I need to linearly scale it down by ⅔, to feed into a 3.3V ADC pin. For a voltage divider, the source has too high ...
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2answers
79 views

Passive voltage drop from 6V DC to 5V DC for 3W circuit

I plan to put an Arduino onboard of my hub-generator powered bicycle circuitry. Currently, I have a circuit consisting of: 6V/3W AC hub generator (variable frequency and power); Rectifier bridge; ...
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1answer
44 views

How to wire this component (-4dB audio)

Getting frustrated because I don't understand what this -4dB thing is in the circuit and I can't figure out how to wire it correctly or even if I have the right part. I have a 3.5mm mono audio jack ...
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3answers
97 views

Why is DC Voltage called Direct Current ?

I have had this question since a long time, and didn't find any other place to ask this. So thought will just ask here. The "DC" in DC Voltage/Supplies stands for Direct Current. So why is it ...
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2answers
73 views

How to add ground to DC circuit?

I'm just a dabbler in electronic circuits and I'm really still kind of a noob. I am working on a project called the "Atari Punk Console" (Originally known as the "Stepped Tone Generator") but there ...
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1answer
85 views

Canon no longer makes CanoScan 8800F AC adapters, help needed to replicate its functionality

The CanoScan 8800F uses a proprietary 32VDC AC adapter that's no longer manufactured. A Flickr user did the trial and error to find out how to modify another 32VDC AC adapter for use with the 8800f. ...
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2answers
56 views

Charging a bank of lead-acid batteries in paralel

I have a lead-acid battery similar to the one in the picture (mine is 15Ah) and I also have a spare car battery (50Ah). Is it safe, or a good idea to put them both in paralel to achieve a bigger ...
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1answer
46 views

6w 12v 5a peltier only drawing 1a, I am supplying more current but its only drawing 1 amp?

I just bought the peltier and its of 60 watt 12v 5a and its maximum capacity is of 90 watt power. I am using my Pc power supply which have ability to provide 12v and 15a maximum. I connect to that ...
1
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2answers
79 views

Question about LDOs and the practicality of this application

I'll try and keep this as organized as possible so everyone can understand my thought process as easy as possible. I will be using a 12V 5A switching power supply (available on eBay) to convert my ...
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1answer
41 views

Determining DC gain of single supply op-amp (no AC component)

I'm building a homebrew PIC programmer, and want to support devices with varying Vpp voltages, so I'm using the DAC output of a PIC16F1825. But the PIC is supplied with a +5V Vdd, so that's the ...
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1answer
57 views

DC offset spike?

A week or so ago, I accidentally damaged one of the speakers of my audio system, most probably because of a loud and high-pitched distortion (noise? - it's basically a "pop" when ...
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0answers
67 views

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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0answers
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
63 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
998 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
57 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
68 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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46 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
77 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
50 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 ...