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Questions tagged [ac-dc]

Questions regarding the safe and effecient design and implementation of AC voltage to DC voltage supplies. Typically Mains to some lower DC voltage.

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2
votes
1answer
558 views

DC bus inversion to 3 phase AC modified sine wave using IGBTs

I'm working with a variable voltage inverter. I have 3 phase AC voltage coming in at 480V RMS line to line. It hits a full wave SCR front end, has a DC bus link, and is inverted with IGBTs to created ...
1
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3answers
3k views

Connecting led fairy lights together powered by ac mains

Iv a set of fairy lights, Rated Voltage 3v, 15mA, I would like to connect four sets together in series (12v 60ma).I can get uk ac/dc 12V 1A Power. Question1 : Do i need to connect a resistor if so ...
0
votes
1answer
94 views

Need a cheap 24Vac to 12Vdc circuit to test car audio amplifier / equipement

I have inherited from a friend a lot of car speakers, amplifiers and related equipements, 'cause his widow says i'm the only friend with some general interest in this field. Most of these stuffs are ...
0
votes
0answers
69 views

What external power supply should I use for Arduino modules?

I build a data logger with Arduino MEGA, SD, Ethernet, RTC, GSM, display module, and thermal printer. I am facing problem with unregulated power supplies. I have tried many power adapters, phone ...
1
vote
1answer
269 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
3answers
519 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 ...
0
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3answers
326 views

How to get rid of voltage drop of this timer circuit?

I'm getting ~ 12VAC pretty stable without load with this circuit However when I try to convert this signal into 6VDC up to 500mA or 1A with AC to DC conversion and a regulator; I get huge voltage ...
4
votes
3answers
137 views

Given the diagram, where do I add/replace a larger capacitor for continued power while bike is stopped?

Following the circuit diagram, included as an image in this guide, where do I replace/add a larger capacitor for continued power while the bike is stopped? My guess is that it should replace the ...
0
votes
2answers
1k views

Why are laptops grounded to earth via 1E6 ohm resistance and desktops not?

I measured a few laptop AC-to-DC adapters. 1E6 ohm between GND pin (goes into the laptop) and earth prong (into the wall). Desktops are grounded directly to earth: 0 ohm. Why this difference?
0
votes
1answer
71 views

Projects that require 2 power supply voltages (Raspberry Pi)

I'm looking for some help building a circuit to supply a Raspberry Pi Zero, as well as a 1W RGB LED driven through a Picobuck driver. The Picobuck needs 12V and the Pi Zero just needs 5V (from a USB ...
0
votes
2answers
493 views

Compact on board AC to 5VDC converter [closed]

So I'm playing around with an idea, but I'd like a good, compact way to power it. In the past I've used old wall warts to provide the power. Just find one with the power output I need, solder the AC ...
3
votes
1answer
642 views

Non-isolated Off-line AC to DC Power Supply

I found two very similar designs (ignoring the LDO on the first one) of this type of supply and was curious if one is better than the other and if so why. I guess a 15V zener is slightly more ...
-1
votes
2answers
1k views

110 V AC to 5 V DC converter circuit and Eagle schematics [closed]

I have a circuit and a microcontroller. The circuit take 110 V AC, and I need 5 V DC to power the board. The circuit is plugged to a power outlet where it takes its power. What I need to do is to ...
-1
votes
1answer
989 views

On an AC-DC adapter, what is the use of the mA number printed on it? [duplicate]

releted to this question I wonder what the use of the number of mA printed on an AC-DC adapter/converter means. I am charging a Bluetooth headset, which came with ...
0
votes
1answer
69 views

Strange signal on minus DC contact [closed]

It should be -11V, but the oscilloscope shows something like this: The frequency of this 'signal' is 100 Hz. And for the +11V it seems to be normal: If I understand everything correctly, the input ...
0
votes
2answers
234 views

This circuit uses a transformer on a rectified DC voltage, what purpose does this serve?

I am trying to design a USB charger from scratch, and I have come across this schematic in the data sheet of a AC-DC converter that I would like to use (NCP1011): Unfortunately the circuit does not ...
27
votes
7answers
6k views

Why is this power adapter transformerless?

I saw a battery charger that converts 220V AC to 6V DC without a transformer. Now I am wondering why many (if not all) power adapters are using a transformer, is it about efficiency or about ...
-2
votes
1answer
2k views

AC-DC 5V 700mA 3.5W Power Supply Buck Converter Step Down Module [closed]

I am trying to implement 220V AC-DC 5V converter on my custom PCB. Anyone can refer me to the circuit schematic that is being used in the referred link below. I am expecting the converter to have main ...
0
votes
2answers
145 views

Connecting varaible DC to PV input of Solar MPPT inverter

I have a synchronous alternator with output of 170~220 VAC and 40~60 Hz (1200-1800 RPM). I am designing a system to stabilize my output to 220 VAC and 50 Hz. So I am working on AC-DC converter that ...
10
votes
3answers
1k views

Can a 50 Hz, 220 VAC transformer work on 40 Hz, 180VAC?

I am designing an AC to DC converter. My power source is a single phase synchronous alternator that has a voltage range of 170~260 VAC and a frequency of 40~60 Hz. Can i use a transformer designed on ...
1
vote
0answers
152 views

How to force USB device to drain 500mA Current for charging?

I designed an AC-DC converter circuit(220VAC to 5VDC@700mA) to create a smart phone USB charger. The Transformer that I used in my design can supply only 700mA current. I searched the Web and ...
1
vote
1answer
68 views

I have a power window motor which is powering a rock tumbler and baffled!

I have two AC / DC adaptors. Model SY-002-5-12 Output 12V_...2A 5V_...2A and Model LX1205 Output 12V_...5A Only the 12V _2A will run the motor. What am I missing? I thought the 12V_5A would ...
0
votes
2answers
503 views

Consequences of inrush current out of specifications in AC/DC power supply

What would be the consequence of an inrush current bigger than acceptable limits at the output of a AC/DC power supply? We are currently using a MeanWell model (GST160A15) whose datasheet reports a ...
0
votes
1answer
142 views

Soldering generic AC/DC to 4 pin plug

So, long story short: I'll soon have a PCB which accepts 24v 5a power input and has a 4 pin power plug of this type: And is wired like this: My question is: assuming I have a generic AC/DC adapter ...
-4
votes
2answers
4k views

Does anyone know an alt code for ac/dc - Alternating Current (AC) Direct Current (DC)? [closed]

I have been trying to find an alt code for the ac/dc symbol, but have not found one or a way to suggest it.
0
votes
1answer
382 views

240V AC to ~380V DC converter at 3500 continuous watts

I have a single phase 5KW generator connected to a diesel engine capable of producing approx 3500 Watts of power I need to convert the 240V AC to DC in order to send it to my solar charge controller ...
5
votes
3answers
690 views

Why AC supply is rectified first before stepping voltage down?

I have opened one of my phone chargers and was trying to understand how it works.. I found IC MB6F just at AC input which came out to be a bridge rectifier. My question is why AC is first rectified ...
-1
votes
2answers
534 views

sensing the existance of the AC power line [duplicate]

I have more than one AC power source and I want to detect which one of them is ON which one is OFF using a Microcontroller. So my question here is what is the cheapest and smallest in size method to ...
0
votes
1answer
95 views

Extremely low power sensors powered from mains (110/220) [closed]

I hope to find some help here with powering of sensor module. I have sensor, that was designed primary for battery usage, so it is extremelly low power, now I was aked to try this sensor also indoor ...
0
votes
2answers
208 views

Wire size for part of the circuit (AC)

I've bought some cheap AC-DC converter online. The goal is to place it inside a roof lamp's base, and power an ESP8266 clone at 3,3 volts from mains (in Europe, so 220v/50Hz). The lamp connection (...
1
vote
2answers
143 views

Are M-G sets still available/in use?

I'm specifically talking about a motor-generator AC to DC converter. Are there applications where you'd need perfect, ripple-free DC current(and voltage) so you'd use an AC motor coupled to a DC ...
5
votes
2answers
1k views

Blown Capacitor and Bad Zener Diode in a Switching Power Circuit

We have got a few boards with failed power. Some boards went alive after replacing a bad capacitor (swollen can). Some boards went alive after replacing a zener diode (somehow shorted to ground I ...
3
votes
1answer
1k views

AC/DC converter problem

EDITED to update diode spec and schematic... I have two failed outside security lights each with PIR circuit with relay to switch 240V AC mains voltage to another circuit which looks to be a simple ...
0
votes
2answers
84 views

What is the term for a DC-AC Isolated Power supply?

I'm reading DC coupling in tube based guitar amplifiers and how avoiding capacitors in the signal chain reduces signal loss, phase distortion, and noise introduction from the resistors that also have ...
1
vote
2answers
2k views

What is the purpose of all these resistors and capacitors in this power supply? [closed]

This is the schematic diagram of pa-12 family laptop adapter. I think it is based on flyback topolgy but i have a problem understanding many things in it. Actually, in many circuits in general ...
1
vote
1answer
218 views

Bias-tee for adding multiple frequencies to a DC line

Objective - To add multiple frequencies on sine waves onto a \$24V\$ DC Line. Each frequency block (\$F_1, F_2, ...\$) generates a sine wave of unique frequency within the given range. When the \$n^{...
0
votes
3answers
3k views

LED Strip Light - Power supply issues

I'm making this right now - https://www.youtube.com/watch?v=qlMtakaa7u8 Each 5m roll of LED takes 60W power (http://www.ebay.com/itm/182028302443?rmvSB=true). He's using two of these rolls, so a ...
0
votes
1answer
950 views

True RMS-to-DC converter with AD736

I built a true RMS-to-DC converter circuit using AD736 chip on breadboard. The schematic is shown below. I'm a little confused with the output that I'm getting though. When I applied a sine wave of ...
0
votes
1answer
359 views

Will the use of an AC relay keep my power supply isolated?

An isolated power supply is used to convert 120 VAC 60Hz power from mains to 12V. A linear voltage regulator then converts the 12V to 5V. A 5V micro-controller is then used to switch on a 12V relay (...
3
votes
3answers
1k views

Will a fuse improve the safety of my non-isolated buck converter design?

I have a power circuit that implements an AC-to-DC rectifier and a non-isolated buck converter to convert a 120 VAC 60Hz signal to 12V and then a linear voltage regulator to step the 12V down to 5V. ...
1
vote
2answers
228 views

Does the transformer in this circuit cause a voltage drop to the DC motor?

In this circuit: Is the transformer and the circuit on the secondary side of the transformer only there for the test-point or does it affect the voltage to the DC motor? The DC motor is a 90V motor ...
1
vote
1answer
218 views

What does “Transient Response Recovery” means in the output specification of a AC-DC power supply?

I'm using a AC-DC power supply to provide 24VDC input to a PCB. A 100uF,35V tantalum is used as one of the filter capacitors for the 24V(same from supply) input of DC-DC regulator on PCB. In some ...
0
votes
2answers
131 views

How is this device getting low voltage?

I've opened up a Lutron dinner, and I'm trying to understand how the microprocessor gets its DC voltage. With my limited knowledge I'm not seeing an AC/DC converter. I've attached pictures, can ...
-1
votes
2answers
1k views

Multimeter reading 0 and drawing too much from DC power supply

So I've got a circuit that requires both 5V and 3.3V so I bought a 5V 2A AC/DC converter from a store, which I will add resistors to later for the 3.3V. Before I connect it to my circuit, I wanted to ...
-1
votes
4answers
934 views

How to convert 700V AC to 5V DC 500mA?

I have a device that requires approximately 500 mA at 5 VDC, and I am required to get this power from two legs of a three phase power supply. The voltage between these legs can be between 110 and 700 ...
2
votes
2answers
107 views

What are the safety and device risks associated with not connecting the grounding prong on a 120V AC device?

For example, imagine a device that comes with a 3-prong (grounded) AC plug. What are the risks associated with, for example, plugging this device into a 2-prong extension cord which effectively ...
1
vote
2answers
481 views

What are design considerations for grounding an enclosed AC-to-DC converter?

Here I'm talking about a device that takes 100-240V AC in, and outputs 10-20V DC out. In terms of grounding, I'm referring to the grounding offered by a standard outlet (e.g., a NEMA-5-15R receptacle)....
1
vote
2answers
2k views

Can I use a Triac dimmer circuit to control the brightness of an AC powered LED light strip? [closed]

I am using this Triac circuit to control the brightness of several incandescent lights. The circuit monitors the phase of the 120 volt wall current, then signals an Arduino when the phase crossed ...
0
votes
1answer
430 views

DC-LVDT Output noise filtering

I am working with the DC-LVDT Omega 620-25 http://www.omega.com/pptst/LD620.html Manual: http://www.omega.com/Manuals/manualpdf/M4345.pdf Specs: http://www.omega.com/pressure/pdf/LD620.pdf I am ...
1
vote
2answers
318 views

Is a capacitive power supply safe?

I'm doing a home automation system which uses a RF transceiver(nRF24L01+) paired with an arduino to control the relays. Since these require low power DC to run I was researching on ac to dc when I ...