Tagged Questions

0
votes
0answers
61 views

ATX power supply front-end: How does this work?

I've been trying to educate myself on general power supply operation and stumbled across several schematics for ATX power supplies. In general I understand how a SMPS operates, and an ATX PS is just ...
1
vote
1answer
73 views

How will the output of a 12V transformer wall wart differ from that of a 12V SMPS brick?

I have been working on a project to drive an electric door strike from an Arduino shield of my own design. Actually, I'm using a Freetronics Eleven and not an official Arduino, which is relevant ...
1
vote
2answers
39 views

Current sense magnetics with critical/boundary conduction PFC chips

I was thinking of using a critical/boundary conduction PFC controller in a boost PFC. I'm not sure how convenient it is to find an inductor with an auxiliary winding. I can find lots of choke type ...
2
votes
2answers
83 views

How to simulate a circuit with LM2576 in it?

Background: I am software engineer with a limited knowledge of electronics. This is a n00b question. I want to design a circuit to step down DC voltage from about 24V to 12V. I have tried a 7812 ...
0
votes
0answers
27 views

Can I wire a PicoPSU with PCI-E in series to a SMPS?

It would look like this: The SMPS model is Mean Well EPP-300-12. It's rated for 300W at 12V/25A
2
votes
1answer
65 views

Can a linear regulator in shutdown mode have the output in parallel with a switching regulator

I am trying to design an efficient battery powered circuit using a 3.3V microcontroller (NXP LPC1343). One of the requirements is that the microcontroller periodically read a value from an ADC and ...
2
votes
1answer
42 views

Confusion over SMPS controllers/regulators

I am looking at datasheets for ICs like FAN4800 or NCP1337. Some of these are PFC boost converters and others are for other types of SMPS topologies. My confusion is that I can't tell if these ICs ...
0
votes
0answers
52 views

Recombining split phase US 240VAC to get normal 240VAC

When measuring voltage on a US residential 240VAC circuit a meter will not show any voltage flowing across the two hot wires. Reason being is this is two 120 volt hot wires that come from a center ...
-4
votes
0answers
26 views

How to repair Olevia TV that won't turn back on after shutting itself off (standby light stays on) [closed]

Was watching the TV, when all of a sudden, it shut itself off and went to standby mode. Now, neither the remote nor the main switch will turn it back on. The blue light stays on all the time. I ...
3
votes
2answers
117 views

Converting universal AC to 3.3v DC @ 0.1A

There's a bunch of topics around this but i haven't found something that fits my requirements. I'd imagine this is a fairly common thing though so any pointers would be appreciated Basically i want ...
1
vote
3answers
94 views

Is it always safe / reasonable to replace a power supply brick with one rated for more amps? [duplicate]

I am specifically looking to replace a 12V 3A power supply that seems to have disappeared from a backup HDD. I found a 12V 5A power supply with the right connector on Amazon, and ordered it without ...
0
votes
3answers
113 views

(When) does an SMPS use a push-pull converter to translate the voltage?

I'm reading up on SMPSs and related technology and have come across contradictory information, or so it seems to me. Various sources on push-pull converters (for example, the English and German ...
3
votes
1answer
48 views

Effect of switching noise on a handheld measurement device

I'm planning to make a handheld LCR meter (plus more) based on Cypress's PSoC 5LP chips. One of their many features is a built in boost converter, which seems an attractive prospect, since it would ...
4
votes
2answers
102 views

How to properly snub transient spikes from a transformer and prevent switch mode power supply burn out

I've received a failed switch-mode DC-DC step down converter (part# LTC3631 from Linear). This circuit was driven by a 24VAC transformer which is rectified on the circuit: simulate this ...
1
vote
2answers
75 views

What is the current limit/saturation of series inductors?

I am currently trying to increase a 12Vdc 30A (from a computer power suppy) to 24Vdc 12A. The circuit I have used is based on a application note for the NCP3063 boost circuit with an external mosfet, ...
3
votes
2answers
224 views

Designing a Transformerless power supply

I am working on a transformerless PSU for maiking a 3nos.x3 watt led, each having forward voltage around 3.6v and current around 650-700ma. I have worked on this kind of circuit: I guess a 1uf ...
0
votes
1answer
63 views

Noise on Bluetooth Low Energy module power supply

I have a bluetooth low energy module (BLE112), which I'm trying to use on my PCB. When I supply JUST the module with a coin cell battery, it works great and I can see it advertising on my wireless ...
5
votes
3answers
217 views

What can cause a Drain-Source short in a FET?

Background: I am using a Si7456CDP N-channel MOSFET in a switching power supply. The power supply and load are housed in a plastic enclosure. Yesterday, the power supply and load were working ...
3
votes
1answer
162 views

How does this circuit regulate voltage?

I have an old Nokia phone charger with 5.6 V output, so I tried to adjust it to 12 V. By changing the Zener diode though I manged to do that, but I can't understand its circuit (I replaced the 9v1 ...
3
votes
1answer
137 views

Synchronous DC-DC converter and fast diodes

I'm a bit at a loss when trying to optimize a DC-DC converter (Half Bridge) and selecting my MOSFETs. Up to 200V I get good results (MOSFET switching times are fast ~ 20ns and the anti-parallel diode ...
1
vote
2answers
90 views

step up/down power supply using mc34167

I'm looking at building a bench supply using a 24V 1.3A DC power supply and a ON Semiconductor MC34167. Along with an appropriate inductor and MOSFET as suggested in the datasheet. I want to make the ...
-6
votes
2answers
69 views

Any body could tell me which MOSFET is perfect for Input Dc 200-2800 and Output 15V @ Output Current 3A [closed]

Please Help me to find MOSFET or IGBT for High Voltage Dc Input from dc input 200-2800V and output 15V @ output Current 3A This is for dc-dc converter which we will use MOSFET.
0
votes
0answers
36 views

Are there off-the-shelf sources for high-frequency high-current magnetics?

I'm often looking for high-frequency chokes. My typical spec ranges are 500-1000 volts, 10-40 kHz, 5-200 amps. Off-the-shelf chokes in that range are almost non-existent from what I've seen. The ...
4
votes
1answer
118 views

Capacitor identification

I am replacing a blown capacitor on my LCD monitor power supply board. While I have the thing in pieces I thought I would replace the other electrolytics as well as they may well fail in the future. ...
1
vote
2answers
106 views

Power adapters logos

Is there a list with the logos which appear on some power adapters? I have two adapters and I'm wondering which one is better for my application. I'm interested especially on the output EMI ...
5
votes
1answer
248 views

Hand winding smps transformer

I would like to hand wind a smps transformer for prototyping work. The specs of the transformer are as follows : Transformer Parameters Core Material: EE16, NC-2H or equivalent, gapped for ALG of ...
2
votes
3answers
390 views

Switch-mode power supply, and output voltage range - unregulated?

This Wikipedia entry specifically on the SMPS part, says: Switched-mode power supplies are always regulated. To keep the output voltage constant, the power supply employs a feedback controller ...
2
votes
4answers
454 views

Why does this buck converter output such low current?

I'm making my first attempt at building a buck converter, as a constant-current supply for a 700ma LED, from a 5V or 12V supply. I have it working with the parts I had on hand, at about 88% ...
0
votes
1answer
104 views

Connecting power supplies in series

I need to draw approx 4 amps for 10-15 hours at a minimum of 18V. I have hooked up two 300 watt power supplies in series: +12V on one and +5V on the other: the output is only +15.8V rather than the ...
3
votes
2answers
147 views

Paralleling MOSFETs or MOSFET and IGBT to increase capacity in QRSMPS

Is there a relatively simple way to increase the load capacity of a integrated SMPS/MOSFET controller by adding a parallel device? This is the device: Fairchild FSCQ1265RT The method has been ...
4
votes
2answers
214 views

Why only 500VAC rating for this Y-capacitor?

I’ve been looking through a reference designs for an off-line flyback converters (this one by Texas Instruments and this one by Linear Technology). Both of them have a Y-capacitor between primary and ...
2
votes
2answers
244 views

Ferrite beads in Quasi-Resonant Switch-Mode Power Supply (QRSMPS) primary?

I am using the Fairchild FSCQ series and I am shocked that nowhere is there any guide for sizing the bead on the drain. The frequency range is 24kHz min. to (looks like) 90kHz. There is also another ...
0
votes
1answer
88 views

Are these two Li ion chargers equivalent, despite their stated spec?

Not being game enough to DIY it (as suggested in some answers to this question) I've bought a 240V charger for my beard trimmer. Despite the singular "240V" listed on the label, the person at the ...
0
votes
4answers
135 views

Enable pin current limiting resistor?

I was looking at the AOZ1280CI DC-DC buck converter, and I'm having trouble properly interpreting the datasheet concerning the enable pin. In the pinout description, it states: Enable pin. The ...
3
votes
2answers
757 views

How to safely ground a switching power supply with floating outputs?

I just received a 120VAC to 5VDC (20A) switching power supply (the kind with a passively ventilated metal casing) for use with a microcontroller project I'm working on (driving long LED strips). I've ...
1
vote
1answer
55 views

Designing Power on failure system

I came a cross a design problem which I need your suggestions in it. I have 3 power sources, Main Supply which is 9-32DC, a battery pack 12VDC, and PoE Module, all are connecte to tripel output 12, ...
3
votes
1answer
265 views

In a boost converter, should ground plane be placed underneath the gate trace?

When designing the PCB layout for a DC-DC boost converter, one does not place a ground plane under the inductor, to prevent induced ground currents. Also, for SMD MOSFETs, the drain (switch node) ...
3
votes
2answers
214 views

Question about transformer design

I want to use a transformer to convert AC voltage. Input is 220V AC at 50 Hz and output is, for example, 5V 30mA AC. Many people told me, this transformer will be huge because the mains frequency is ...
-2
votes
1answer
210 views

ATX power supply troubleshooting [parttern of failure] [closed]

I'm troubleshooting a ATX power supply and I found that fuse has gone. Then I replace the fuse, Then fuse burnt very violently. Then I trace the tracks and found that RL207 diodes , 3 out of those 4 ...
1
vote
1answer
147 views

Obtaining +- 1.5V, +- 20V, and 3V from single LiPo [closed]

I want to use a 3.7 volt LiPo to power a portable device. What's the best (efficient and small) way to get ± 1.5V, ± 20V, and 3V from a single cell LiPo? Here are some specs about the ...
0
votes
1answer
103 views

SMPS power supply shows strange AC voltage output

Hi I have been using a simple laptop power adapter (15V) for my electronic lab-works. And today I'm troubleshooting some RF circuits, and I found a little guilt about ground loops, So I check ...
4
votes
2answers
178 views

Can electronics be damaged by plugging into a lighting dimmer circuit?

So my stupid room is wired so all of the lower receptacles are driven from the electronic wall dimmer. Stupid me plugged in my brand spanking new brother laser printer into the lower receptacle. It ...
3
votes
2answers
366 views

Why does a multimeter show VAC on VDC power supply output?

I used my simple digital multimeter to measure the real output of several small PSU's I have got at home. They all should give just direct current and show some values in VDC mode, but the multimeter ...
2
votes
3answers
262 views

Why gate drive transformer is not connected directly to the gates in this App Note?

Here’s a circuit from TI App Note SLUA323, which shows a synchronous rectification in a current doubler circuit. U2 is a gate driver. Transformer T2, which looks very much like a gate drive ...
1
vote
2answers
146 views

Why is there always fixed rated current for an SMPS? [duplicate]

Possible Duplicate: Choosing power supply, how to get the voltage and current ratings? I have a conceptual question about the rated current shown on a laptop charger. And I assume it is a ...
3
votes
4answers
234 views

Checking maximum current provided by charger, how?

Using only an entry-level multimeter (and an assortment of common discrete PTH components, say on a breadboard), what could be a reliable way to check the maximum current that a switched-mode AC-DC ...
2
votes
3answers
188 views

Power management for a bus/self powered USB device

I'm building a development board similar to the Arduino, with similar power sequencing requirements. It has both DC and USB power support, and it should prefer DC power. The DC input needs to support ...
1
vote
1answer
170 views

alternative fix to: How can I calculate a Joule Thief

This is based on the original question: "How can I calculate a Joule Thief. How Can I calculate a Joule Thief. Since the gain of common emitter voltage amplifier and it will depend widely on the ...
3
votes
1answer
191 views

SMPS design, requirement of generating High Frequency

Question: Is that requirement of converting 50Hz to a higher frequency in SMPS (Switched Mode Power Supply) is just to reduce the transformer/inductor core size? Background: Since as we all know ...
0
votes
1answer
402 views

Reparing a Chinese power supply Unit

My Chinese phone usb charger has gone. I opened the lid to repair it, and this is how it looks like (picture below). Actually how it looked like after I removed Q1 for testing. I suppose it has ...

1 2 3