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Questions tagged [step-down]

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7
votes
2answers
6k views

Is it possible to step down 240 AC to 5 DC without transformer?

Microcontroller which is controlling mains voltage circuit requires 5 volts to operate. Is it realistic to use diode bridge followed by capacitor to straighten the ac wave and then use voltage divider ...
7
votes
1answer
598 views

Step-down with external mosfet - why heavy current surges?

I built this circuit, which is supposed to deliver currents up to 20 amps (when everything else works...). The purpose is (eventually) to build a constant current source (as opposed to a constant ...
6
votes
1answer
625 views

Drop voltage a bit

I have this ATtiny13a mcu led setup that uses total of 33mA when both leds are on and it works perfectly when powered through usb output. My problem is that now I want to power it using a 6V 500mA ...
5
votes
10answers
2k views

Best approach to step down 220VAC to 160VAC?

Hey Electrical Engineers, I'm a newbie to electrical engineering (I am a software developer by trade and am starting to work with Raspberry Pis and want to learn about basic circuit design). My ...
5
votes
3answers
6k views

Do Step-Down Transformers Increase Total Power Consumption?

Firstly I am not at all experienced in electrical matters so forgive any wrong terminology. Here's the situation: I recently moved out of US to a country that uses 220v. We have a single phase step-...
5
votes
2answers
587 views

Buck converter - Spikes on output at switching frequency

I've been using LT1158 to make a step down switching regulator. I have an input frequency of 50kHz and this is my circuit I put 22 Ohm 50 Watt resistor on CON1 as a load. I got this output measured ...
4
votes
2answers
4k views

Input voltage for feedback pin on LM2596 Voltage regulator

I am using LM2596 for a dc supply where I could alter the output voltage. Datasheet here. I have setup according to page 9 "Adjustable Output Voltage Versions". Everything worked fine. The output ...
3
votes
4answers
569 views

Heat problems when using 5 buck/switching converters in a double isolated enclosure?

I want to use 5 step down converters (220 VAC -> 5V DC) inside an enclosure inside an enclosure (double isolation). The step down converters are similar to these. There will be 5 of them, where one ...
3
votes
3answers
339 views

How to efficiently power wireless sensor node from a 9V battery?

Context I have recently set out to add some wireless features to my entry-level smoke detector. Problem In order to achieve that, I will be adding a custom pcb embedding an ATmega328P and a ...
3
votes
2answers
1k views

Setting a step-down regulator to provide constant drop on the following linear regulator

I would like to have a clean output from a linear regulator (variable 1-5V) but also a small heatsink on it, so I thought about placing a ready-to-use step-down module before it, and to wire it so ...
3
votes
4answers
1k views

Step down transformer for vintage tube amplifier

Hi so I've just bought a 60's tube guitar amp from the U.S, I live in Australia. Through searches across the internet I've found a few potential issues with the safety of running the amp through a 240-...
3
votes
1answer
231 views

Cause for failure after short circuit Step-Down Converter Input

I'm currently evaluating the Semtech TS30042 step-down converter. My input voltage is 24V, output voltage is 5V. I followed datasheet recommendation in my layout in most aspects. The problem is, as ...
3
votes
1answer
1k views

Ground fault protection for fault on delta side of a wye-delta step down.

I have a distribution circuit with a primary 4-wire 21 kV and secondary 3-wire 12 kV circuit. The two winding transformer is a (grounded) Wye-(closed) Delta transformer. I know that if I have a ground ...
3
votes
3answers
932 views

Step-Down/Buck-Converter: How to replace feedback voltage reistor divider to electronically control the regulator output voltage

Most today used switching regulator ICs that I've seen have some kind of feedback voltage pins. I think I've pretty understood the way it works: A resistor divider from output to ground is created to ...
3
votes
2answers
208 views

Low cost 30A 24Vto12V stepdown converter [duplicate]

I'm trying to design a 24V to 12V step down converter. Power efficiency is not that important to me, but I want to come up with the cheapest solution possible. I don't need isolation neither. So I ...
2
votes
2answers
730 views

Is it possible to convert 19.5V 3.33A to 12V 5.5A?

I have a laptop charger which has 19.5 V 3.33 A output. I want to use it for raspberry, which needs 5V and 2.5A and for monitor which needs 12V 3A. Is that charger strong enough to run the whole ...
2
votes
9answers
2k views

The Relation of power heat losses with V & I in transmission lines

The voltage is stepped up at the beginning of transmission lines and step down again at the end of the latter. This is, of course, to reduce the current passing through the line and thus reducing the ...
2
votes
3answers
2k views

What is the difference between monolithic and non-monolithic dc-dc converters?

What is the difference between monolithic and non-monolithic dc-dc converters? For example this is monolithic dc step down controller: LTC3609
2
votes
1answer
5k views

How to read this transformer label

I have the following transformer that takes in 117V and steps down to 12V and 9V. However, I don't understand the label. "PUR" and "RED" are listed as 117V, does that mean PUR is power and RED is ...
2
votes
1answer
3k 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 ...
2
votes
2answers
100 views

Step-Down convertor. Why does the input voltage go to the output

At the moment when I insert the USB cable, at the output of the converter, 5 volts appears for a short time. Why is this happening? Circuit: Voltage Oscillogram: BUT! When I connect the ground ...
2
votes
1answer
80 views

Will a buck converter allow current to pass through if Vin is less than the configured output voltage?

In general, will a buck converter allow current to pass through if Vin is less than the configured output voltage? Specifically, I'm reading the TPS54308 datasheet and I'm not seeing an answer to my ...
2
votes
3answers
1k views

MP1584 DC/DC step down converter cause whine in audio, how to avoid?

Short story I use the MP1584 to step down 5VDC to 1.5VDC to power an audio equalizer taken from a Panasonic walkman (RQ-P255) from the nineties. However this is working great, sound is great, it ...
2
votes
1answer
220 views

switching power supply pcb layout

I'm studying for the best practice to route a switching dc to dc step down regulator. Particularly this TI part. On page 37 there's a layout example. I was wonder if it could be any problem to place ...
2
votes
2answers
570 views

Cooling buck converter mosfets by placing on bottom layer of PCB - a problem?

I have a design and layout for a buck converter which currently sits on one layer of a 2 layer PCB. I would like to force-cool the heat generating components of the board by placing them directly onto ...
2
votes
1answer
3k views

How should I step down 220V (ac) to 180V for a DC motor?

I have many treadmills motor of rating 180V 10A which I would like to use for power tools. Locally we have 220V ac 50Hz. I thought of using iron-core transformers. But having one for 1800W+ is ...
1
vote
1answer
1k views

AMS1117-3.3 from 5VDC show 0.09vdc

Hey all I am having an issue using this AMS1117-3.3 SMD: According to its documents it says its either a fixed or adjustable version? So I hook it up as I see in the documents: The left pin (1) ...
1
vote
2answers
2k views

Is it OK to use switching regulators to charge mobile phones (and such)?

I had several issues with car usb adapters (dc-dc step-down regulators), and I'd like to make one myself. Issues: Nokia cell phone refusing to charge Motorola phone power supply circuitry fried ...
1
vote
1answer
136 views

Inductor for Switched regulator

I'm implementing a Step-Down Switching Voltage Regulator with Vin = 12V, Vout = 5 V 300mA and I followed the application which is in the page 13. I have no doubts in choosing all the components ...
1
vote
3answers
127 views

How many capacitors are needed for a step down circuit?

I'm tyring to build my first step down component using TPS562219 to get 5V output from a 12V input (instead of 1.05V output shown in the example). But as I'm new to this electronic stuff, I have some ...
1
vote
1answer
209 views

Step-down converter and ceramic minimum ESR capacitor

I'm building a step-down converter, based on the TI TPS5450, which provides a reference design and various considerations on the capacitor. Even on the minimum ESR required. But when states "The ...
1
vote
1answer
7k views

Dropping 12V to 7.4V

I'm trying to power up my NXT Mindstorm Brick which needs 7.4V (at least, that's what the battery output is) with a 12V Power Adapter. I'm doing that because I want a constant supply from the socket ...
1
vote
2answers
631 views

Best way to power a 12V-2A load using 18650 Li-Ion batteries

I would build a small present for my friend's child who has a 3D pen like this: 3D pen link By now it only works with an AC-DC adaptor, so it always requires a wall plug. My idea is to build a ...
1
vote
3answers
461 views

Understanding a variable 220v AC to DC Power Supply

Can someone just please explain how and why the diodes D3 D2 and D4 are used? Why D3 is single while D2 and D4 are in series? How do we calculate the capacitance of capacitor required in a circuit ...
1
vote
1answer
228 views

Need help with stepping down DC volts

I don't have much experience with electronics, I'm simply trying to get (at least what I think) is a fairly simple circuit running. I've got a blower fan that I need to get running. It uses 12VDC at ...
1
vote
1answer
760 views

Why is Rack Mounted Step-Up Transformer Not Industry Standard?

I'm tasked to source a 1U step up transformer so that customers with only 120 VAC mains power can utilize 240 VAC for our products. I've contacted TrippLite and APC who both offer a 2U (2 rack unit) ...
1
vote
1answer
315 views

lt1076 buck boost converter outputting voltage that is too low

I am using this buck boost converter from the lt1706 datasheet: It should take 10 to 40V and output 5V and 2A. But when I proto boarded it it only outputs 2.2V and I really need the 5. I am giving it ...
1
vote
2answers
85 views

How to efficiently trigger QC and convert it to constant 5V and a peak of 5A?

Introduction For a university project I started working on RGB LED Shutter glasses, which are based on the idea of a kickstarter by Macetech. However, these glasses miss some features I was looking ...
1
vote
1answer
53 views

Is it acceptable to replace 2 parallel 100uF capacitors for LM2596 with two 220uF capacitors

I have a printer motherboard with the LM2596 IC. The older version of the motherboard had one 100uF capacitor at the output pin of LM2596 but LM2596 recommends that 220uF be used. Because a cheap ...
1
vote
1answer
234 views

Step down transformer 220Vac ~ 380Vac

I have a 10W AC/DC converter that works in the range of 80~265Vac and I was using it with an input of 220Vac, but now I need to supply with 220Vac or 380Vac. I was thinking about using a step down ...
1
vote
1answer
760 views

Is a diode an effective way to replace a resistor in an application where heat should be avoided?

Currently with my project where I removed some christmas lights from a string, I used a resistor in place of the removed bulbs successfully. (Note: Skip down to "Diode as replacement?" section for ...
1
vote
1answer
66 views

What is the most convenient way to make/buy step 66V DC down to 12V DC?

There is a big battery that I have which has 64-67 volts, and I need constant 12 DC volts from it. I tried ebay, but the best buck converter that I found had limit of 55 volts. My local electronic ...
1
vote
1answer
80 views

Find out how much current a mains adapter can supply? [closed]

I have a mains adapter without an enclosure which delivers 12V. Is there a way to find out how much ampere I can draw from it max/safely?
1
vote
2answers
412 views

MP1584 inductor calculation

I would like to calculate the inductor value for MP1584EN.The datasheet says: $$L= \frac{V_{out}}{f_s \Delta I_L} (1- \frac{V_{out}}{V_{in}})$$ On the first page of the datasheet there is a typical ...
1
vote
1answer
65 views

Constant battery voltage

I purchased a RC car and tore out the electronics and replaced with an Arduino. I am powering the DC motor from the battery but when it loses capacity it loses power. So the current is varying. For ...
1
vote
3answers
438 views

Voltage Drop across Diode

I have a 6V input on my board. I need to put a load switch for USB 3.0 which needs 5V. I need to stepdown 6V to 5V using a series diode. 6V is going to other circuits also. Can someone suggest the ...
1
vote
1answer
565 views

Ideal ripple current on a DC to DC step down switching regulator

I was studing a linear's datasheet, a step down DC to DC switching regulator. More specific: the LTC3615. I am a little bit confused with ripple curent which involved to inductor value calculation. ...
1
vote
1answer
1k views

Step Down Regulator - Output voltage unstable/voltage drop with load

I'm currently trying to build a USB charger device for my mobile phone using an old 12V car battery as power source. I purchased different step down modules (see below) to regulate the voltage from ...
1
vote
0answers
67 views

DC-DC buck output voltage

I am designing a DC-DC step-down converter (asynchronous) and I would like to achieve a Li-Po charging with it (18 - 22 V input voltage). My goal is the CC/CV charging but to do this, I need constant ...
1
vote
1answer
276 views

TPS63070 Buck-boost not bucking or boosting correctly

Can some check my layout since I am using TPS63070 buck-boost regulator and I would like to get 4.7V output at TP12 but I am getting 11.5Vwhich is wrong and don't know why? Base on the Datasheet R1=...