Power supply Definition and 302 Threads

Suppose I have some resistor with resistance R. Using a typical power supply, application of a voltage difference V across the resistor leads to a current draw of I = V/R according to Ohm's law (so long as the only circuit element is a resistor without any complex impedances). Now, suppose I...

Today's switch mode power supplies for computers mostly have a nominal voltage range of 100 to 240 volts. Whatever the added cost of making them operate over that much of a range there is must be less than the cost of having separate products for the two major narrow voltage ranges used...

Hi. Does anyone knows about a DC power supply that can switch between forward bias and reverse bias automatically? For example, I start it with forward bias, after 1 minute, it will automatically switch to reverse bias, and after another 1 minute, it will automatically switch to forward bias...

Hi all, I'm brand new to the forum and dreadfully new to electronics in general, but am doing my best to learn and I figured this may be a good place to start. (ps - this is not homework..I'm not a student of an electrical engineering, just an enthusiast trying to learn :)). I'm trying to...

I have a ccd camera that I put a peltier element into, and there is noise from the power supply, even when it isn't plugged in. Just plugging the jack in gives noise, I tried the bypassing thing with a capacitor with no effect. Plugging the PSU in gives no change. I tried moving the power supply...

http://img683.imageshack.us/img683/5329/unledtw.png So its basically a power supply with a voltage regulator LM317T at the end. The question asked to find the voltage ripple across the capacitor. So I basically solved the peak voltage found which would be 12V * SQRT(2) = 17 volts...

Hello i need a 9VAC 1.3A source but it's hard to come by... is there a way i can use a similar source? i don't know too much about this sort of thing but from what i understand the power output is more important than the individual current or voltage out... is that right? for example, my...

Hello all, I am interested in placing a static charge on a conductor by means of an electrical circuit. One way to do this is by means of a Van de Graaff generator which uses the triboelectric effect to generate net charges, then places them onto two conductors having equal but opposite...

hi everyone, here is picture of power supply:-- http://img696.imageshack.us/img696/8841/powersupplyg.jpg at top it says power supply can give 3A. would this mean when resistance is 10 ohm is used and voltage is set at 30v. then current will be 3A. please tell me. what is the function...

Hello all, For my project, I am trying to measure the solute concentration of water inside a porous ceramic plate (~2mm in diameter). I am using platinum electrodes. There are two ways I think I could possibly do this. 1) Place two electrodes on the sides of the porous disk 2) Place 4...

I want to convert my power supply into a "lab power supply" but a lot less simple. I just want a 12V output on it. The power supply has 2 12V rails. Is it possible to connect both rails to increase amperage? Thanks for you input.

Hello, could someone please verify the proper way to supply power to this particular DAC chip: http://focus.ti.com/lit/ds/symlink/dac813.pdf Do I need to supply both +15 V and -15 V into +Vcc and -Vcc respectively? Or do I just supply +15 V to +Vcc and have the negative return lead of that...

Hey all, I've got a high voltage power supply that I need some sort of connector for. It's a 40kv 15ma output and the connector screws in over a hole that leads to an enclosed plastic tube with a metal rod about halfway down. Are these standard connectors or do i need to do something crazy to...

I've been looking ahead in my textbooks and reading some stuff online, and there's some things I'd like to know about DC power supplies. The DC power supply we have at school has 3 independent outputs, 2 variable and one fixed. How would they be isolated from each other like that...

why do we use a dual power supply? Why, for instance, do we use +12 and -12 volt instead of just a 12 volt power supply.

anything?

I currently have a slim-line PC I bought real cheap. http://www.abcwarehouse.com/product_catalog/pc_proddetails.asp~prod_id~34788# I paid $200, not bad. Well, the case is Custom, as is the internal power supply. The video card is lacking, and I know there are quite a few pci-e...

Hi, I have an ups used for my PC. I have just replaced his faulty battery and checked the output on battery operation with a multimeter.The reading are as follows: 1. Without load the ouput is about 184V. 2. With load the output is between 196V to206V. Can someone tell me if I use the ups...

I'm evaluating a wall-transformer type power supply used to power guitar effect pedals as a replacement for a 9V battery. It's rated at 9V and 2000 mA. I put resistive loads on it of (nominally) 16, 8 and 4.5 ohms, and made measurements with a Klein Tools MM1000 multi-meter. Here's what I...

Im using the 7809 IC to get 9v regulated dc supply. However, I'm also getting about 14v ac in the output as well. I've tried putting a notch filter tuned to 60hz to remove the ac voltage, but its still there. I'm using this power supply to power tl072 op amps and I'm worried that the ac voltage...

Hi guys and gals, please forgive the lame-o title, first poster here! I recently picked up a pretty fierce interest in electronics and I've been doing plenty of reading and experimentation but I have a few questions that I'm hoping will land on generous ears. What follows is a "brain dump"...

This is a very silly question. I can't believe I have forgotten. I have a 30v bench power supply and I am looking to test an op-amp running at +/- 15v. I have a supply which has a negative output/ positive output and inbetween a green common/earth output. How do I wire them to produce the +/-...

Hi, I'm trying to understand how to correct when you put Vcc as 10V your max output is like 9.18V. Is there a factor on the data sheet or what? I'm trying to build a bi-state multivibrator to generate a 10V peak value but it's being saturated. thanks.

Why use high frequency power supply for generating plasma?? Hi everyone, I noticed that for the plasma ball common in science museum, power with high frequency should be used for generating so called plasma inside to give out colorful glow. But one thing I can't understand is why power supply...

Can anyone tell me what the most standard way of changing the frequency of an AC power supply is? Can it be done with circuitry or does the method of generation need to be set at the desired frequency?

Hello, About me...so you know where I am coming from. If you don't want to read, skip to the end-ish... I'd like to start off my saying that I know next to nothing about electronics although I am eagerly reading the All New Electronics Self-Teaching Guide right now and it is confusing but...

I need a power supply for my M-Audio Keystation 61es MIDI keyboard, and I think I might have one that will work for it. The user manual for the keyboard says this: But then their website is selling a 9v 500mA as the proper replacement...

Homework Statement In one of my labs for a circuit analysis class we are told to design a simple DC power supply. The power supply will have three outputs, +4.5V, -4.5V, and an adjustable output from 0-11V. I have already done most of this and the question I have is could you design this so...

Will this power supply work for my device? URGENT! I have a Mini-fridge I need to get usable again. Recently, as of a few minutes ago, I opened up its power adapter to find that capacitors have burst and that would be the reason of the fridges death a few months ago. Given the mini-fridge is...

Hello, I am trying to design a foundation for an audio preamp that is powered by a single 9V battery. I am successful so far except the single power supply part. I am using the voltage divider scheme to get a +4.5V and a -4.5V reference voltages. With no load the supply voltages are close to...

A circuit has a battery(V), Capacitor(C) and Inductor(L) connected in series. At t < 0, the switch is open and the capacitor has an initial charge of -800uC and Io = 0.0Amps.. When the switch is closed at t = 0, I want to know what happens here. I only understand an LC circuit where there is...

Why are SMPS smaller than linear power supplies? I understand when you switch at high frequency, the transformer,inductor and capacitor size reduces. Usually, there are 2 transformers in a smps. One at the AC input and one after switching. How do they rectify the 60Hz using the first...

I am an EE student and would like to get my own power supply so I can experiment at home. I saw these two power supplies at frys and was wondering if they are any good. One is 0-30V 0-3A and the other is 0-60v 0-1.5A. I would like to experiment with making audio amplifiers. Which one of these...

Power supply -- Importance of amp Rating?? Hello all: I have a TV tuner that requires a DC 7.5 volt, 500 ma power supply. I have a 110 V input power supply rated at 7.5 V DC 1,000 ma. Can I safely use this powersupply with the tuner. Analogy: I can plug a 3.5 am vacuum cleaner into a 15...

Homework Statement For an electromagnet that is just made up of wires and a core, what power supply can I use other than batteries that let me adjust the volts? Can you explian in detail? Homework Equations none The Attempt at a Solution I have already looked on the...

Assuming I have the same voltage, correct polarity, and sufficient current, can I generally replace any class 2 power supply with any other? This will be used for common household electronics. In particular, when researching power supplies, I see specifications for ripple, noise, setup, rise...

Greetings, Does anyone know how to use a laptop's charger to externally charge its battery? I am using a battery from an old DELL laptop to power my handheld radio. I wish to use the charger that came with the computer to rejuvenate the battery, however, the charger circuitry is smarter...

I would appreciate any help, opinions or explanations on this as I am receiveing many different views currently. I measure the discharge voltage of a single power supply (laptop ac charger) using a digital chart recorder. On a trial and error basis I achieve the data as close as possible to...

Ok so i received the suggestion to get such a power supply by rigging a variac to a bridge rectifier, but variacs are rather expensive, so after some snooping around i came around this site: http://www.scribd.com/doc/9779212/ebook-free-energy-50000-vdc-power-supply they basically just use...

Could some one explain how a bridge rectifier works with a diagram and its mathematics? Also please explain how a center tap transformer and a bridge rectifier are used to provide a symmetric power supply. I have the Ckt Diagram for that but I cannot understand its working. thanks...

I want to know if I am figuring correctly. I am putting together a 12 volt 3 amp DC power supply. The formula in the instructions is C = Tc / R. I figured the required cap to be 20,750 uf. When I went to a couple of supply catalogs to check the price for the cap I found that no one had had a...

Hi, I'm new here so I apologize if my question isn't composed appropriately. I’m currently designing water cooling unit, which is a component of a larger project, that utilizes peltier plates as a heat pump to displace the energy from the water. To cool the peltier plates themselves I...

OK, so if I'm inputting 120V ac @ 1.5A equals 180W and my output is 19V dc @ 3.16A equals 60.04W simple subtraction says 116W is left. that can't be right can it? am i doing this wrong or am i actually losing 116W of power?

Just a quick question for you guys out there. I have an AC/DC laptop power supply. I was thinking of using it for a few projects. Th power supply's output is 19 volts and 3.16 amps. My question is is 3.16 amps the max current that the power supply can take without frying? I mean the number of...

I am expermenting with a sperical metallic neodymium magnet ball that spins like a DC motor when I hook up a + or - charge up to the north or south pole of the ball and then hook up the other charge to the equator of the ball. I have only used alkaline batteries and it works with a AA 1.5 volt...

Does anyone have a circuit diagram for a power supply that outputs about 25kv at a few mA dc. 25kv is just a ball park figure it could be 22 or 30 kv, or even better adjustable from 22 to 30. Input would be 230v ac Thanks.

Ive recently completed a project in microcontrollers (my first project with uc's actually) and I built a power supply which gives me 12v and 5v dc. I use a transformer to step the voltage down to 12v AC from mains and then the 12v AC is converted to 12v dc using a bridge rectifier with a...

http://img104.imageshack.us/img104/3557/1234uyq.jpg Ok, there are a few calculations on this problem that I am having difficulty with. This is a past homework assignment which is why the answers are filled in. They are all correct. Anyways I approached the problem in this manner: V...

I am trying to figure out a better way to power 150 leds that need 3.4v and 20mA with a 12v,1A power supply. Right now the best way I can think of is have 3 leds in series and a 100 ohm resistor at the end(50 times). Is their any better way so I can use less resistors

So if you have something like this: https://www.amazon.com/dp/B0002H07CW/?tag=pfamazon01-20 can you use it as a -9V supply? My circuit requires a +9V and a -9V supply, and since I am having issues finding fixed +/-9V supplies, i was wondering if i could just use a 9V supply for the +9V, and...