12 volt DC to 48 volt DC

[murphyslabrat]

I wanna get a big ol' fan in my box! But, it uses 48v DC...SO, what would the best way to convert that current. I would like to spend as little as possible, so were talking ~$5...

thanks for any help,
-Murphy

 

[Matthias99]

You certainly aren't going to find a premade 12->48VDC converter that can push adequate current for a "big ol' fan" at 48V for $5. I doubt you could even build one for close to $5.

You need something like this, though maybe not quite as much power.

120VAC->48VDC might be cheaper.

 

[murphyslabrat]

LOL, definitely out of the question then.

I just had this vision of cutting a 172mm top and front blowhole...

p.s. what about 24 volt at 1A?

 

[Jeff7]

DC -> DC conversion isn't too simple. With AC, you can just use a transformer, thanks to the fact that it creates a fluctuating magnetic field. DC creates a constant magnetic field, so other tricks are needed to boost it.

Your other option may be to just buy a 48V or 24V power supply and run the wire in through the back of your case. Or else find yourself a 12V fan. Like this one, perhaps.

Marlin P. Jones and Associates has a fair selection of power supplies, but I don't know about anything for $5 that can push enough power. It also might not be a good idea to get a power supply rated exactly for what you need; it's better to have a bit of extra headroom.

 

[pm]

For $5, this is not possible unless you do the work yourself. As others have said, you will not find a DC->DC voltage converter - particularly a large enough one for a fan - for $5.

I spent a while on the reverse - I wanted to go from 48V DC to 12V at about 3A. I have an electric vehicle and I wanted to power the headlights (12V) off of the primary battery pack (44V 19Ah lithium ion). I stared at this and threw various ideas around and decided that it basically can't be done for $5. For $20, maybe. Then I came up with a solution for my problem, but it won't help you.

For what it's worth, I would do 120V AC to 48V DC. Get a transformer, wind it for 2.5:1 (winding transformers is not as bad as you might think), and then a bridge rectifier and a couple of larger capacitors and you should be set. If you can use a transformer from something else, the whole thing should be relatively cheap to do - probably under $10.

 

[MrDudeMan]

Originally posted by: pm
...

For what it's worth, I would do 120V AC to 48V DC. Get a transformer, wind it for 2.5:1 (winding transformers is not as bad as you might think), and then a bridge rectifier and a couple of larger capacitors and you should be set. If you can use a transformer from something else, the whole thing should be relatively cheap to do - probably under $10.

that was going to be my suggestion. its fairly easy to do and definitely works well enough to drive a fan.

 

[slackwarelinux]

If you don't want to bother with voltage conversion but still want an epic fan, goldmine electronics has a surplus 12VDC 25 watt fan. It would required a modded case, but it puts out about 235 CFM.

Anyways, here it is.

 

[highwire]

This is my Value Engineering approach: Cost 50 centavos up.

Assumption: Typical construction, no electronics in fan.

Just Run the motor directly from 120 vac with a series diode.

Tech notes:
Since typical motors of this sort have considerable inductance, the effectivive DC voltage will be about 30 or 40 VDC. This might be OK for the application by reducing the fan noise. Could be just right . Also, because of the motor inductance, the current will be smoother than the voltage. ( the AC current ratio will be much lower than the voltage waveform would indicate.)

A second approach is to use a 5-20ufd film cap as a series element from 120vac feeding a bridge rectifier to the fan. The cap size will determine the fan voltage as will the actual fan current characteristics. This approach will cost more, but should also be under $5. Cap should be 200 volts+ and not electolytic.

 

[silverpig]

You need a 48 Watt fan? Geez, your box will sound like a jet engine.

Also remember that air has to go somewhere...

 

[dajeepster]

why don't you just take the money and buy a 12VDC fan...