It's very difficult to add active PFC into an existing power supply. However, an external PFC unit can be used. A PC power supply will accept 370v DC from the PFC unit with the switch set for 240v.

Well, the digital speakers will eliminate most of the EMI noise. The remaining hiss will be due to the amp. It doesn't have a high enough SNR to produce sound (or no sound) without introducing noise into the signal. Unless you really want to spend a lot of money (for high-quality speaker, not just ...

Of course, had I been consistently working with 230VAC I probably would have had someone else do it. I dont mind 115VAC as much. Ive been zapped a few times, but its no where near as dangerous as 230v is. One side of 240v is only the normal 120v. It's only more dangerous if you touch both sides at ...

Have you tried JB-welding it back together?

I want to buy an UPS in the near future, but I'm not sure about capacity. What I want is quality and silence, so I'd go for an APC Smart UPS - for the true sine wave. I'm not sure if the 420 VA one would be enough VA != W It's 260W, apparent power is only important with non-PFC PSUs. 100+W for CRT ...

I don't know of any consumer grade UPS that has a fan that's "on" in normal operation. Many high power UPS'es including APC1200 that I have, have a built in fan that comes on during power loss, but it's off during normal operation. I'm fine with that since if the power is down I have far bigger pro...

The also built a kiosk in the library that overlooks the solar panels. Turns out they run several PV cells in series, and it's something like 180VDC they run down to the inverters inside the building. I'm willing to bet that 180VDC -> AC -> 12VDC is less efficient than 180VDC -> 12VDC. However, I a...

The also built a kiosk in the library that overlooks the solar panels. Turns out they run several PV cells in series, and it's something like 180VDC they run down to the inverters inside the building. I'm willing to bet that 180VDC -> AC -> 12VDC is less efficient than 180VDC -> 12VDC. However, I a...

I guess the question for me is how much "extra" power is drawn when whatever's plugged into the UPS is off. I have an older APC UPS, model BE350C. I measured it once a while back and if memory serves, it uses about 6 watts, definetly less than 10, when its on but nothing is plugged into it. Try mea...

Look at some of the smaller ones. Those tend to be fanless and are therefore quiet. Make sure there's a switch to disable/delay the buzzer if that's a problem. I recommend APC since they're built well and include several important safety features.

Now, there are some power supplies that are "mostly analog". That implies that the there's a little bit of digital circuitry (often just from the comparator to the power MOSFET) to improve efficiency. (A LM393 along with a power MOSFET, a fast recovery rectifier, and inductor, and a few resistors a...

A digital signal made up entirely two voltages (usually ground and a certain input voltage) will become a steady voltage of intermediate value when put through a low pass filter This is called "Switching Mode Power Supply" (SMPS). a) You don't need any digital logic to control SMPS, most SMPS/PWM c...

Digital power conversion technology is not that new. In fact, virtually all new PC power supplies are based on digital technology. The way it works is by the mathematical principle of integration. A digital signal made up entirely two voltages (usually ground and a certain input voltage) will become...

a Scythe Infinity mounted to the compressor in passive mode might be all the cooling it needs. A Ninja is Infinitely better in passive mode, but beware! there have been reports of loose fit with Scroll-775 compressors (Edit: me too) The scrolls are not that loud. However, a mere 1/100th of an inch ...

I've been racing for years with electric RC cars. I've used a lot of NiMh's. And also fried some, due to bad handling... boom ! There's a lot of hype and woodoo, when the talk is about NiMh's. For some applications, slow charging is nice. But try that on a RC car, and your car will be very slow. Bo...

the resistance of this particular fan sample was about 150 ohms. DC fan motors are more or less AC induction motors with oscillators built in (except for ECM fans but those are generally made for high power instead of low noise). As such, decreasing the voltage increases "slip", decreasing efficien...

My first thought is that if they're not plugged in, they add nothing. If the firewire port is unused, then the circuit is not complete and it can't be drawing any power. I would think that would extend to any un-used component. Anytime something is plugged in, unused or used, would be a different s...

Cool project--I actually have roughly the same thing running already. P3-450 384 MB PC100 (I have nothing else to stick this PC100 ram in :D) 2 SMC 10/100 NICs 256 MB CF card with CF=>IDE adapter Runs BrazilFW nicely--firewall, router, VPN, and if I ever get around to it, a WAP gateway as well. Bot...

My Netgear rangemax 240 was $40 because it was going out of stock at frys. It is one of the best routers available. It can handle 194 connections and 96mbit WAN speeds. I'm making a router that is more of a firewalled gateway (basically a DIY "Cisco"), not a WAP. I already have some nice wireless r...

I set the voltage to 1.3v (as low as it will go without replacing the voltage reference) and set the clock to 550MHz. Using a Pentium 1 heatsink, it remained cool with just 5v on the fan. And at 5v, the fan was more or less silent. It passes memtest86 and some CPU stress programs so I consider that ...

You are aiming for business setups I suppose (or at least, multiple users setup). I don't think they are ready (let alone needing) this type of setup. For most users here (most are home users, not corporate users), hot swapping is not a hot item, I presume. You need: Multiple users Pump for seconda...

Your solution is very expensive. Indirect cooling systems always are. The advantage is, you can indeed locate the "noisy" scroll compressor outside (this will mean the primary stage is very hard to move), while treating the secondary stage as a watercooling system, but with very low temperatures. h...

You've just described a vapor-compression refrigeration unit. Not really a new technology IMO. Except it doesn't work the same as a Vapochill unit. While the Vapochill cools the CPU directly, my design first cools a glycol solution which is then used to cool the CPUs. I plan to make it possible to ...

Rusty075: you're right: heat pipe is a durable component. Failure can mainly occur in case of bad bending of the device. This could make air to leak into the heat pipe through micro-cracks (some times really hard to inspect) and mess up the entire device. Actually, if it cracks, what really happens...

I think the law of diminishing returns comes into play here, in that there's no straight-line relationship between voltage and speed. Also, no matter how low you set the clock speed, it will refuse to run after a certain point as you lower the voltage. You'll need to go by trial and error, I'm afra...

I have a new technology in development for quiet and fast PC racks. It aims to cool CPUs very effectively while keeping noise low. It also allows PCs to be placed closer together, saving space. It cools better than traditional watercooling or air cooling, allowing CPUs to perform better. How it work...

If I underclock a 733MHz P3 (Coppermine, 1.65v default) to 550MHz or 366MHz, about how much can I reduce the voltage and still get reliable operation? Note that the main objective of reducing heat is to make it easier to design and reduce the size of power supply circuits. Low noise is an objective ...