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Questions tagged [power-supply]

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

25
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6answers
30k views

How efficient is a capacitive power supply?

Something like this Falstad sim version of it (I'm tired, I keep making mistakes, so please excuse me for the second time.) Now these are not very safe PSU's, due to the lack of isolation. But in ...
9
votes
4answers
5k views

Easiest and Best PoE Ethernet Chip/Micro/Design for DIY Interface with Custom Arduino Board (AVR Solution)

I am looking for a PoE Ethernet chip that I can incorporate in a design I plan on using along with some of the Arduino features. I would prefer to implement a standalone mcu for the Ethernet device ...
3
votes
2answers
916 views

Capacitor to provide power to a circuit during a very small interruption

I need some help in figuring out what size capacitor I need, and if my idea will even work. I have a small remotely-controlled helicopter, and a very small camera. I am trying to record video while ...
2
votes
2answers
1k views

Mini ITX PSU and Power Brick Wattages

So I have 4 systems with mini itx power supplies and am looking to purchase power bricks from the manufacturer. What confuses me is the power bricks are 102 Watts while the PSU can do 160W with a max ...
2
votes
1answer
561 views

Pico ITX Power Supply and AC-DC Inverter

So I have four computers all using these little pico itx power supplies and was wondering rather than have 4 power bricks attached to these power supplies could I just use an Power-Bright-PW900-12-...
1
vote
3answers
895 views

Ipad charging via usb port

Ipad doesn't charge while in use and connected to the usb port. It definitely charges when connected to the supplied 10 watt power adapter. The USB port, as far as I know, supplies 5 watts. Can we ...
13
votes
4answers
10k views

What are the basics of making a rechargeable battery pack?

We have a device that runs off of a AC adapter, or a pack of 8 AA batteries. Since in normal use we use both, it would seem to make sense to have the battery pack recharge while using the AC adapter - ...
3
votes
2answers
1k views

High side current sensing in DIY bench supply

I would like to build DIY linear bench power supply, with adjustable, regulated output voltage and current limiting functions. The voltage and current regulation will be implemented using analog ...
12
votes
5answers
1k views

What are some alternative power sources for wireless sensors?

I'm looking to power several small, Wi-Fi enabled sensors, in a domestic home or office environment. As such I'm interested in keeping them powered as long as possible between charges. Obviously an ...
3
votes
5answers
349 views

How can computer parts suffer if the computer isn't protected by an UPS?

In datacenters it's common to use Uninterruptible power supply (UPS) to protect the computers. They are used for several reasons, but one is that electronics possibly can suffer from the power grid if ...
8
votes
3answers
3k views

Help with power-loss protection using capacitor

I designing a circuit will store log data to an SD card. The information will be coming form a parent circuit that this one plugs into. The parent circuit will supply 5V to my daughter card. The ...
7
votes
7answers
6k views

Dummy battery shells

I have a device that takes two AA batteries and I want to replace it with my own external power source and regulation circuitry. Instead of clipping or soldering wires to the device contacts, I would ...
8
votes
3answers
8k views

How do I design a device to automatically switch to the backup battery?

I've been told that many kinds of batteries work best if they are used until they are completely drained, and then recharged. (Edit: The "memory effect myth" is quite widespread. Batteries work just ...
6
votes
2answers
7k views

Connecting arduino and separate power supply grounds

I am working on an arduino project that uses transistor switches to power on high power leds that are powered by a separate 24 volt power supply. My issue is that I have two different grounds, making ...
3
votes
4answers
966 views

Delayed power supply startup

I would like to make a circuit that turns on a power supply to a microcontroller after holding down a button for a period of time (say 2 seconds). To make matters slightly more complicated, if ...
9
votes
8answers
7k views

Is it safe to use a DC power adapter that isn't UL Listed or CSA certified?

I picked up a 9V switching DC adapter from SparkFun a while back, but I've been hesitant to use it because it doesn't have any of the usual "safety" approvals that you normally see on power adapters (...
3
votes
3answers
428 views

Power supply amperage

I have a small PSU board out of a defunct DVD player that I'd like to use as a supply for my breadboards. It has two rails, +12 and +5 with two GND lines, but there's no current indication. My guess ...
26
votes
7answers
31k views

How to find the ESR of a capacitor

I am building a power supply circuit, and the switching regulator (L4963) calls for a low-ESR output capacitor. The capacitor in question is C3 of the evaluation board circuit. What does "low" mean? ...
5
votes
1answer
712 views

setting up an electronic load

I have an electronic load that I want to use to help me with some ATX switch mode power supply repairs. The instructions that came with the load were rather sparse and I haven't found much for my ...
13
votes
3answers
10k views

OpAmps - Single Supply or Dual?

I'm trying to pick an op-amp and I'm having trouble figuring out if the op-amp needs a positive and a negative power supply or if I can connect it to ground and the positive supply. What do I need to ...
16
votes
7answers
4k views

What if I overload a cheap AC adaptor?

I'm experimenting with PIC microcontrollers and various related circuits both on plugboards and simple homemade PCBS. I'd like to use various old AC power adaptors I have lying around to power my ...
18
votes
4answers
17k views

What is “foldback short circuit protection” in a power supply?

I am looking at buying a 24V power supply. Two of the options are these: PSP24-060S 24 VDC 2.5A (60W) power supply PSB24-060-P 24 VDC 2.5A (60W) power supply The first offers "foldback short circuit ...
3
votes
3answers
630 views

How do I build a cheap/efficient mains adapter for some LED lighting?

I've been considering building some LED lights to replace the mains-supplied lights in my house (as a more efficient alternative). For it to be worthwhile though I'd need to build an efficient UK ...
4
votes
6answers
4k views

Converting 24VAC to 5VDC - Need transformer demystification

I've got an automatic litterbox that 'needs' to be hacked for better control. As it ships, it comes with a 120VAC to 24VAC (300 mA) wall wart that drives the two motors in it. I'm trying not to change ...
4
votes
4answers
5k views

DIY Beginner's DC Power Supply? [closed]

My school uses HY 3005D-3 but I want to do it myself to save on $. Before opening it, I ask for tips about: not-to-break-it, cheap DC supply and DIY-materials (not that I know them soon). So how to ...
10
votes
8answers
9k views

+/- 9V DC Power Supply

I am working on a simple audio mixer project. The op-amps I am using (LM741) take +9V and -9V inputs. I am currently getting this by wiring two 9V batteries together, connecting + on one to - of the ...
9
votes
1answer
1k views

Isn't it overkill to use a regulated power supply for a nixie tube?

I've seen any number of nixie tube designs on the web that use regulated 170V supplies for the nixie tube anode. Wouldn't it be possible to use unregulated, half-wave rectified 170V peak power for ...
4
votes
2answers
2k views

Looking for a Wall Wart Power Supply with an Earth Ground Connection on the Output

I am looking for an AC or DC output wall wart power supply that provides an isolated output and brings out the earth ground connection to the output. Specs -- Either single output or bipolar output ...
6
votes
3answers
2k views

Can I Filter This Split Power Supply?

I've got a battery powered synth that uses two 9v batteries to make a split rail power supply (±9 and ground). I'm trying to use a regular AC-DC power adaptor to replace the batteries. The adaptor ...
3
votes
2answers
9k views

Mains Hum Filter

Are there any chips or simple circuits available for removing the 50/60Hz mains hum from a regular power supply unit? So I've got a few bits of audio equipment that have bad PSUs and they have a bit ...
6
votes
3answers
448 views

best quick&cheap power supply inverter

I have a +5V power supply and need to invert to a -5V supply sourcing about 25mA. I've got an LMC7660 running now. It's ok for the short term, it outputs -4.4V with 100mV p-p switching noise, but that'...
5
votes
5answers
24k views

How much current do you require in Arduino and embedded systems projects?

How much current do you require in Arduino/Sanguino or other embedded systems projects? After responding to the LM2575 inductor question I started to take a closer look at the TI power DC-DC ...
3
votes
2answers
2k views

Inductor for LM2575

Can anyone suggest a 330uH inductor and associated Eagle .lbr for use with an LM2575? I've been looking all day for this! Any suggestions would be appreciated.
6
votes
2answers
2k views

Can I combine the power supply?

Here's the circuit I'm working on, it's a robotic stringed musical instrument thing, that uses 6 DC motors and an Arduino Duemilanove - The resistors are 0.25w 1KΩ The transistors are TIP122 ...
4
votes
4answers
797 views

1.25-28V var. power supply mod

I have a 1.25 to 28 V variable power supply I'm working on. here's the schematic (from here): What I'd like to do is put in a fan (12v 0.16A) so it runs when i turn it on, however i don't know where ...
2
votes
2answers
2k views

power supply unit for Arduino/solenoid project

I'm trying to find an off the shelf plug in ac/dc power supply unit to work with my project. I want to power an Arduino Duemilanove and six 12v 1A solenoids. Here's the solenoids -> http://www....
7
votes
8answers
1k views

Investing in a bench-top power supply

For my projects I have always used hacky power supplies: wall plug + 7805, a USB port or an ATX PSU. I am looking at getting into 3.3 V circuits and I am having trouble getting hold of the necessary ...
6
votes
3answers
3k views

Wide voltage supply for PIC microcontroller

I am looking to power a PIC with a supply voltage that ranges from 4.5 V to 18 V. This will be a battery powered device so I would like to conserve power, i.e. linear regulators like the 7805 is less ...
7
votes
2answers
449 views

Where to cut my power supply for Arduino?

I have no vocabulary for this, so forgive my clumsiness in explaining. I need to hook up a power supply to use with solenoids and an Arduino, but I'm not sure where to cut it. Just before the power ...
7
votes
3answers
2k views

DC boost for low voltage?

I have a project where I'd like to convert a 0.5 V, 800 mA supply (a solar cell) to at least 3 V with as much efficiency as possible. I've seen DC boost converters, but all the ones I've seen are ...
27
votes
6answers
23k views

How to convert AC to DC

I am designing a circuit that needs to output 5VDC @ 1A. I'm trying to use a wall transformer to step the voltage down to 12VAC. The next step is the diode bridge and ripple capacitor. The ripple ...
35
votes
5answers
14k views

Switch between 5V power supplies?

I'm designing a board that can be powered either by USB or an ATX power supply. They can both be plugged in at the same time, independently. I'd like the ATX to provide 5V if its plugged in, but ...