An electronic device which supplies electrical energy to a load. Can be AC or DC input. Typically DC output.

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18 views

What is a class 2 power supply (NEC Article 725)?

What is a class 2 power supply per NEC Article 725? Does a power supply with between 0 - 20v classify as a class 2 power supply? More specifically, would NiMH (8 AA in series for 9.6v) or lithium ...
-1
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0answers
17 views

240 or 120 VAC input options to 120 VAC output without switching a 240/120 switch

Hopefully this drawing helps. ( 2nd attempt at post ) The power supply takes L, N, Earth Ground for 120 or L, L, E.G. for 240. We want customers to be able to just wire in either without forgetting ...
2
votes
2answers
392 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 ...
1
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2answers
63 views

Power dissipation

In electronics, we always calculate power dissipation of components and devices all the time. I understand why we do this (heat issues and power supply), but there is something I never really quite ...
3
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4answers
820 views

How do I design a 2A or more power supply for my consumer USB devices?

I understand that many of my consumer devices charged by USB ports can charge at higher rates than 0.5A. However, in testing, I've found they don't consume more than this. Test Setup I have a ...
0
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1answer
42 views

Strategy for powering surveillance cameras

I would like to install 16 surveillance cameras All the cameras are connected to a DVR, 25 meters away (at most) All cameras are powered by 5V-DC, around 3W-6WS for each camera. I have two strategies ...
1
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1answer
49 views

How can I power 7 IL151 5mm Clear White LED leds for a sculpture in a series circuit?

I am in the midst of planning a sculpture. The sculpture will require 7 IL151 5mm LEDs with a forward voltage of 3-3.5v . I have NO experience in electronics and I've been looking around and people ...
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1answer
30 views

ANT-MMCX and Microstripe line and UHF RFID module circuit designing

Below, you see the only schematic of a 6 pages-datasheet of an UHF RFID module (working frequency = 840...930 MHz): There are three questions: What is that ANT-MMCX? I search it in Google and I ...
2
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2answers
236 views

What's the purpose of having two of the same value caps in parallel?

Why does this 5V circuit use two of the EXACT same value capacitors? It's not needing a larger capacitance issue considering 100nF is relatively small. Here is the full schematic: Arduino Leonardo ...
0
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1answer
50 views

ASIC Power supply requirements

I am a newbie in ASIC design process and have a question. What is difference (or pros and cons) of shorting the voltage supply pins(which have the same voltage requirements) in package level or in ...
0
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1answer
49 views

Usefulness of line EMI Filter on bench power supply

I have read this pdf file about EMI filters. I'm about to construct a variable bench power supply of 12V/5A. Will there be any usefulness to add an EMI filter to the primary windings of the ...
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3answers
42 views

How to apply HT gradually in a valve amplifier?

For valve amplifiers, it is said, that applying anode voltage before the valve is heated reduces lifetime and can have other negative effects on circuit lifetime. To avoid this, I want to add a ...
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0answers
31 views

Power Pi and LED-Matrix with one PSU

I am new to electronics, so excuse me if my question is very silly. I have a banana Pi and a LED-Matrix like this one (http://www.adafruit.com/products/1484). I want to power both of them with one ...
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0answers
19 views

Powering Qualtek 320-5

so I recently purchased the Qualtek 320-5 for a project and I have to admit that I have never used anything other than traditional benchtop power supplies at school that come with plugs in the back. ...
52
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7answers
3k views

Why is my circuit so incredibly sensitive to electric fluctuation?

I recently finished building a circuit showcased in a beginner’s electronics book. I have included the picture of my creation below because I think it may become relevant to the question. At the ...
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0answers
34 views

Inexpensive off-the-shelf programmable supply [closed]

I'm putting together an experiment that has a number of blocks that require a variable power supply that will be controlled by LabView (or possibly other) software instance controlling the experiment. ...
0
votes
2answers
83 views

When should I use opto-isolators and isloated DC-DC converters?

I am using multiple DC-DC converters to obtain 12V and 5V. Shall I use non-isolated or isolated converter for Arduino's? From what I have read so far, isolated are used when you have inductive ...
0
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0answers
31 views

Dual Power Supply Failsafe Logic [duplicate]

I need some help wrapping my mind around the following issue: I have one device that I want to be powered by a main power supply (18V), however in the case the power line drops (e.g. gets ...
-1
votes
1answer
64 views

Can I Charge a 12V Battery While It's In Use? [on hold]

I have a Time-Clock (Where employee's check-in and check-out to track working time). Currently set up like this: 12V Adapter >> Time Clock So whenever that 12V adapter loses power, the time clock ...
0
votes
1answer
67 views

Using 15 V laptop charger to power 14.4 V speakers

I recently moved from the U.S. to the U.K., to find that the mains voltage is different. Sadly, my speakers do not have a regulated power supply, as they were only designed for U.S. mains. ...
-3
votes
1answer
62 views

What could have caused a short circuit on a power adapter? [closed]

So, I've got a device without a power cable. I've found and used a old one I've found lying around. After getting the device to work, it started to smoke... What could have gone wrong? Here are some ...
0
votes
3answers
60 views

Power supply PCB

I made a PCB board (my first one) recently and I ran into some issues with it while troubleshooting. The PCB board is connected to an Arduino and draws 5V and the 3.3V supply from it. Also, the board ...
0
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0answers
30 views

Buck Converter power supply based on astable oscillator and zener diode feedback?

simulate this circuit – Schematic created using CircuitLab I've asked several theoretical questions about this before, but I've assigned values and changed my circuit quite a bit. The ...
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4answers
158 views

Troubleshooting PCB of an ATX power supply?

Im new to PCBs, know the basics of electronics and testing of individual components. I have a PCB (of an ATX supply) that is not working when I power it, so I thought of testing each components like ...
0
votes
1answer
38 views

loading on rail voltages in OPAMP

if an opamp is having +15/-15V rail to rail voltage, is there a way to determine how much will either of these power supply get loaded? will they get loaded equally? what happens if I use +18, -12V ...
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1answer
36 views

Rechargeable battery, power multiplexor and charging battery

I have a Raspberry Pi and a bunch of peripherials (web cam, WiFi dongle, H-bridge + DC motor, servo). Alltogether they consume ~4.5A when everything is active. And I would like to make this device ...
0
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1answer
44 views

Diodes to drop voltage for RF module

I am making a standalone battery powered arduino project which uses nRF24L01+ for radio communication. nRF draws 20 mA current max. Can I use 3xAA cells along with 2 diodes (which drop 0.6*2 = 1.2 V) ...
0
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1answer
49 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 ...
1
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1answer
29 views

Feedback in hybrid power supply

During my research of PSU I came across schematic from Linear's datasheet: 1) Whats the purpose of node which is going from output to SW pin of buck converter? 2) Is node which provides 6V ...
0
votes
1answer
37 views

Which 9 V DC Adapter Need for MB102 Breadboard Power Supply

Easy question. I'm a noob... I bought a MB102 breadboard power supply unit. But, it doesn't come with a manual. I need to get a 9V adapter for it. So, I'm not sure what I need. Does the 9V ...
0
votes
3answers
82 views

Calculate voltage of Led driver required for a given amount of led's

I have built some LED lights for my fish tank using six of these LED lamps: http://www.ebay.co.uk/itm/261813680886?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT I have tried using ...
0
votes
3answers
112 views

Capacitive power supply working principle [closed]

In a transformerless capacitor-input power supply how does the capacitor reduce 230 VAC to 12 VAC? Can anybody explain it with mathematical calculations?
0
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1answer
31 views

High Power LED strand Power Supply

I have an LED circuit built that requires 12V @ 6A (72W) to run at approx 80% max rating of the LEDs. The circuitry works but all the power supply/adapters that I have been able to find with those ...
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votes
1answer
79 views

How or where can I get a 120VAC to 3.3VAC power supply?

I'm using a safety gas valve (commonly found in household stoves) for a hobby project. The valve is rated for 3.3VAC, 3.6Amps. The problem is that AC-to-AC power supplies are quite rare, and I had no ...
0
votes
1answer
39 views

Non-diode OR-ing solution for n equivalent power sources

I wish to allow powering my circuit using at least one of 3 connectable periphals. For example, my application could have 3 usb ports that each connect to different usb hosts. Any combination with at ...
1
vote
0answers
36 views

Why does a cap in front of a choke input suply reduce rectifier current? How to calculate optimal value?

As I was designing the power supply for my tube amp, I was trying to reduce the negative transients of the choke input supply, I tried to add a capacitor in front of it (C1 in the schematic). It ...
1
vote
1answer
60 views

I don't understand transformer power ratings

I'm befuddled. I have a wall wart power supply that supplies 65W (it's for an Intel NUC). I'm interested in building my own power supply that will put out... several different voltages and currents. ...
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votes
2answers
84 views

Periodicity of sinewave

I am studying about continuous time periodic signal in that I saw some examples of sine waves and I have a question. The example is \$sin(400 \pi t)\$ is periodic or not. The explanation is given that ...
0
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0answers
39 views

Can I use a single power supply (as in, I plug going into the box

I am trying to put together a headless audio player. In my little wooden box, I will have: A Raspberry Pi (5v DC, micro usb) A DAC Board (5v DC, 2 pin jst). This can be powered from the Pi but I ...
-1
votes
0answers
13 views

12v led strip, 5v power supply [duplicate]

I'd like to know if I can use an AC adapter with 5V and 3A to power up a Led strip of 12V with 24W/5m when I'll only use about 2m of it. I made the maths and the current will be about 0,8A for the 2m, ...
-3
votes
1answer
47 views

roland micro cube fuse? [closed]

My power supply fried one day. While troubleshooting (like a fool) i twisted the cap to the t800 ma 250 volt fuse? I guess that's it. Its soldered on the board. I pulled the cap off and the glass ...
0
votes
2answers
45 views

Li-Po Battery Charging and UPS [closed]

Scenario: The main device is a bank of Li-Po 18650 batteries as the main power source. Sometimes the device will be plugged into AC power when needed for longer periods of time than what the battery ...
8
votes
10answers
2k views

Is it really OK to supply more current than what the component is rated for?

In this heavily upvoted answer the answerer states that it is okay to supply a component with more current than what it's rated for. The analogy is that (paraphrasing here) "If Johnny wants to eat two ...
-1
votes
1answer
49 views

Power supply issue with LM384 audio amp

I made an audio amp using the LM384 : My soldering skills aren't great but eventually the circuit itself doesn't look too bad. To power it, I used an old laptop power supply (18.5VDC - the datasheet ...
1
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1answer
37 views

Automotive power supply - considerations for selecting fuse

A power supply circuit for a device that runs off the 12V battery of a car, is shown below. simulate this circuit – Schematic created using CircuitLab LM7805 is used to generate a 5V ...
0
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1answer
20 views

Sizing Photovolatic cells based on solar load

I'm designing a Photovolatic system to power up a certain electrical load (around 1000 Watts). I've just finished my solar calculations determining the optimum tilt angle and the optimum surface ...
0
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0answers
50 views

Understanding Royer oscillator (for wireless power transfer), (specially mosfet gate driver circuit)

I need to understand how exactly this circuit works, there is not much references and books on those circuits, they're used as "power" oscillator for DC AC conversion for wireless. i finally found ...
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0answers
29 views

Converting 12V DC to 7.4V DC [duplicate]

What i'm trying to do I would like to power my DSLR Camera using an external PSU PSU - 12V DC - 21A Camera's battery - ...
2
votes
2answers
285 views

Where exactly does the ground line go in an AC-DC power supply?

I'm working in the United States. I'm looking into working with mains power, and I cannot for the life of me figure out where the ground line connects. For example, a simple power regulator from mains ...
0
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0answers
25 views

Limit large currents in a small space?

I've built a variable voltage bench-top power supply from an old printer adapter. I cut off the output wires, and soldered in connections to a buck converter module and a potentiometer. The limit of ...