A switch-mode power supply (SMPS) switches been fully-on and fully-off states quickly to maintain voltage regulation. They offer lower power dissipation and run cooler than linear regulators that continually dissipate power through a transistor.

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Microcontroller-based SMPS designing

Is it feasible to construct a variable voltage SMPS using one of each of the following: ATtiny84 microcontroller IRF4905 power PMOS 2N7000 signal NMOS 4.7mF cap 220uF cap AD5280BRUZ100 100kOhm ...
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19 views

Parallel transformer outputs

If I fed in ~140 volts at 100kHz to This transformer what is the most power I could get out of it? The data sheet rates it at 36 volts DC 3 amps on one of its three outputs but I am confused by this. ...
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84 views

Using a transformer with 400 volt rated primary side with a 120 volt line

Is it possible to use a transformer rated for 360 to 400 volts on its primary side on a 120 volt line? Will it still perform adequately? And I would assume the turns ratios still apply? This is the ...
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38 views

Arduino detects voltage on ground

I've been having a hard time finding a solution to this problem. I recently ordered a 5 Volt 2Amp AC to DC switching power supply from adafruit.cc When I connect my Arduino's analog sensor to the ...
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24 views

finding mosfet driver IC [on hold]

I am repairing a subwoofer amp smps. In the smps the mosfet shorted(no.PFF12N65) and 8pin driver ic blasted. I see a code SK322 on remain part of the smd ic but main code of ic cant see. So I request ...
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175 views

Relay not switching immediately from switching power supply to battery backup

WARNING This project as currently described is badly flawed in a number of ways that are liable to lead to complete failure of the equipment. As it is stated that it is intended to be used in a life ...
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57 views

switch mode power supply capacitors

If I am laying out two switch mode power supplies right next to one another from the same supply(24V), one is switching to 5V and the other to 12V then do I need both of the input capacitors? Thanks
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85 views

First steps in building Switching power supplies

I want to make a 50Amps switching power supply, I have already done 10A linear ones succesfully This time it has to be a switching power supply one so, any ideas or tips of where to start are ...
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80 views

Practicality of driving LEDs with high voltage?

After watching someone build a fairly wasteful project, I wondered if there was a better way. The LEDs are cheap chinese variety, with a forward voltage of around 34-36V @3A, and they throw off about ...
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43 views

can you make a generic smart charger?

I have a project in mind, to build an intelligent 3 stage charger from either ardruino or rasberri pi. I plan to have a voltage and amperage monitor, and via the press of a toggle button have the ...
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122 views

What's wrong with my switch mode power supply circuit?

I'm using a TPS54383 dual output SMPS IC from TI, putting out 12V and 5V; at least in design. I created a schematic and board and had it sent out to OSHPark and soldered it all up today and only the ...
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43 views

switching power supply - why doesn't P=VI seem to be true?

A few days ago, i bought an Edimax SP2101W to be able to measure the power consumption of my PC under different load conditions. Some of the figures the device gave me were 259W, 1.3A 477W, 2.5A ...
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64 views

Dual smart battery design and PCB layout

I have a system that is powered by a 7.4V Lithium-Ion battery. The system, which is a combination of processor module and sensors, draws a varying amount of current at varying voltages (5V, 12V, -12V, ...
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65 views

Does an ATX power supply have any isolated outputs?

I am working on an application that requires isolated power inputs. Wondering if the standard ATX PSU has any isolated outputs? Why are we having multiple ground pins on the Connector?
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27 views

Help with designing negative part of Dual-Sided SMPS

For a project of mine, I'm trying to make a dual-sided SMPS that has independently variable positive and negative supply rails, current limiting, short circuit protection, etc etc... My current plan ...
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45 views

How to estimate max current draw from an unknown PSU? [closed]

I have a couple of PSU boards from Sony PS2 consoles. They convert 230VAC to 12VDC and would be useful in a couple of my future projects. Unfortunately there's no information how much current they ...
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89 views

How can a Ultralow Voltage Step-Up converters start up?

I've read about step up converters working from unbelievably low voltages (20mV), namely the LTC3108. How can circuits even start at those low voltages? Diodes, FETs and BJTs shouldn't switch at ...
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238 views

Why do we need bulky filters at the input stage of SMPS designs?

I usually see costly and large filters at the input stage of switch mode power supplies. Isn't the AC signal already filtered by the large capacitor (the 100\$\mu\$F one in this example) after the ...
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109 views

3v3, 12v Smps: “Design ok!” “Pcb ok!” Why not stable? Please Help

Im working on a project and i need 3v3,5v and 12V in this. I though smps circuits would be better than Linear Regulators. So i choose LM2676-adj IC. I designed schemetics for 3V3-3A SMPS and 12V-3A ...
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59 views

Dual Power Supply Switch?

So the question is short, how do i connect a single switch to a circuit that has a dual power supply (+/-) connected to it? Or do i have to use an special kind of switch?
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83 views

Via's in switch mode power supply

I'm using a TPS54386 and currently designing a PCB layout. The data sheet says to avoid via's within a certain loop; I was wondering what would happen or if anything would if I went ahead and placed ...
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75 views

How does reverse leakage current of a Schottky diode come into play with a SMPS?

Looking at diodes for a low power switch-mode power supply I'm designing. I'm not quite sure what the reverse leakage current value is, or if it's relevant in the component selection.
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39 views

TPS54383 switching regulator components.

I'm trying to build a switching regulator using the TPS54383 dual output regulator, Now I've got most of the components and schematic figured out here. pdf Except the inductor's and diode; I'm ...
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94 views

Why do we compensate PWM controllers?

I have been studying switch mode power supplies for a while. I have understood the working principle of several common topologies But there is a detail in the control circuit structures which I still ...
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107 views

Why the voltage drop is so high in my Half-Bridge SMPS?

I have been building an offline Half-Bridge SMPS of about 300W with a friend of mine. We need a variable range from about 10V to 30-35V. We finally got it working and we could achieve 10A at 30V. The ...
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69 views

Set ground reference of a 5v DC power supply to the middle of a 24v DC power supply

I have 2 isolated AC/DC power supplies. one generates a regulated 5 volt power supply and other generates a 24 volt power supply as you can see in the picture below: I also have designed a circuit ...
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103 views

How reliable or trustworthy are LTSPICE demo circuits?

I'm looking at a few switching power supplies and one of the demo .asc files for the particular controller I was looking at really seems to fit my requirements. Can I use their schematics in designs ...
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118 views

PSU not providing enough current

I am using a computer PSU to power a 92 watt(12V 6A) peltier device.The PSU has a rating of 450W,it has got 2 rails of 12V ,one delivering 15A and another delivering 16A.However when I connected my ...
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75 views

What is the purpose of a Zener diode added to the output of a SMPS?

I studied circuit diagrams of some computer ATX power supplies. Some of them have got a Zener diode at the very end of 5V stand by line. The picture shows endpoint of the circuit - the SMPS is on ...
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30 views

Is a 100K+ 200vdc 100ma smps for audio possible?

Ideally a variation on this at a higher switching frequency. Would this board need to be changed very much to have it switch at 100K at 200v/50ma? http://desmith.net/NMdS/Electronics/NixiePSU.html ...
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29 views

Switching mode power supply ground island

I'm currently designing a 4 layer PCB with multiple buck converters on it and I would like to ask for suggestions regarding the best possible grounding scheme. To avoid that these converters ...
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62 views

Convert a device that is powered by a 12V 2 amp ac-to-dc SMPS to a battery powered device

I have looked up my requirements in all possible sources (Google, StackExchange, DiY boards, etc.) but I have not been able to find a clear answer to my problem. What I have is a device that needs ...
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81 views

Can I build a high-frequency SMPS choke out of an arbitrary coil of wire?

Suppose I want to build a boost converter that runs at 100 kHz, with an input voltage of 600VDC and an input current of 100 amps. (This is hypothetical, I know the semiconductors involved would be ...
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59 views

SMPS Inductor oversized vs properly sized

I am working on an SMPS for boosting an input voltage to drive a single string of LED's. The input voltage range is from 18 to 32 volts. The output voltage needs to be about 60V and the drive current ...
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96 views

SMPS regulator blows up, could it be a layout issue?

I have a curious problem which I have been trying to solve for a few days now and I just can not understand what is going on. I have designed a SMPS which takes 24V input and outputs 5V (which is ...
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84 views

Switching between two output voltage

I have a sensor which generates signal in range of 240mV to 940mv. Now, I use amplifier of voltage for my sensor, which generates output signal in range 350mV to 1000mV. I used rail-to-rail ...
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43 views

half bridge … transformer and devices overheating

I have made a SMPS for Audio Amp with the following Spec Input Voltage range - 100 - 270VAC Line frequency - 50Hz Output Wattage - 550W Output Voltage - + - 50V @ 5.5A These are very basic ...
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35 views

Why is the output voltage of the forward converter is dependent on the duty cycle?

The Wikipedia article "Foward Converter" claims that the output voltage of the forward converter is $$ V_{out} = D \times \dfrac{N_s}{N_p} \times V_{supply}. $$ Where, \$D\$ is the duty cycle. Here ...
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61 views

Connecting devices powered by separate SMPS without common ground

I have a power over Ethernet design using the SI3402 PoE PD chip to generate 3.3v for a pic 18F67J60. The switched mode voltage converter in the SI3402 is a little unorthodox in that it switches Vss ...
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52 views

Switching power supply using faraday cage and EMI protection?

Several switching power supplies in the market use this kind of cages to protect the circuit, however, i have this question, A) Is this used as a faraday cage due to the high frequency used by it? ...
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95 views

SMPS: What is current mode instability (aka “sub-harmonic oscillation”)?

In peak current controlled switching power supplies, there is a phenomenon called “current mode instability” aka “sub-harmonic oscillation”. What is that? Can't seem to get a good explanation of ...
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200 views

What is the advantage of a switching over a linear power supply?

I want to build my own switching power supply. I already know how to make a 10 Ampere Linear supply, and I'm wondering if I should bother. What do I have to learn to do a switching supply? What makes ...
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70 views

Info on transformers? Where to find?

I'm quite often taking things apart to salvage the parts and use them in my projects. Right now I'm taking apart an old PC-power supply for a switch-mode lab-supply project. The power-supply in ...
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74 views

Capacitors vs buck/boost converters

I'm trying to drive high power LEDs with a laptop power supply, and wondered if I should use resistors to limit the extra current, or something like this to limit the current. If I did use that ...
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56 views

Switching Power Supply makes speakers hiss

I have a computer with a 5.1 soundcard, that I'm using to run a standard PC 2.1 setup (Corsair SP2500) on the main audio output, and two rear surround speakers I had laying around. The speakers in ...
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53 views

Using bench power supply to drive ex-cordless driller

Ok, so I perhaps naively thought I was the first person to ever think of this - go figure. Anyhow I managed to get my hands on a couple of cordless drillers which have an expired battery and thought ...
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89 views

Simultaneous Buck-Boost or Flyback Regulator - Help Selecting Chip [closed]

I have been trying to find a switching DC power supply that outputs a constant voltage of 12VDC, given a variable input between 4V and 25V. It's to my understanding I'd need a buck-boost converter, ...
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131 views

Boost regulator: Unexpected output voltage

I just finished setting up an LM2577 as a boost converter, and have run into some unexpected issues. For starters, here is the recommended "typical application circuit": My application circuit is ...
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82 views

Strategies for powering an ATtiny micro controller and 40W peltier from mains

I'm trying to power an ATtiny1634 at 5VDC and a 50W peltier element at 12VDC. The microcontroller will, amongst other things, turn on the peltier via a 5VDC non-latching relay. I want to use an ...
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106 views

DIY wifi radio radio NOISE!

I am building a mono, internet enabled, WiFi radio and I have a problem. I am running into what I believe may be a grounding issue. When I turn the system on, I hear all kinds of noise coming from ...