12V down to 5V

[drunken_panda]

How can I get 12V down to 5V? I am working on a project that runs on 5Vs.

[atobe]

resistors is the only thing i can think of

[LiquidClen]

Resistors.

[drunken_panda]

So how would I calculate my resistor value? Would I use V=IR? If so what would V be? 12V or 5V?

[Tercel GTS]

You can just go to wal-mart and buy an adapter that plugs into a lighter that has adjustable output. Radio shack has these also.

[touringcamry]

What are you trying to power? How much resistance or current does it need?

[drunken_panda]

I want to hardwire my MP3 player into my Camry. It draws 5V at 1.5A. I have one of theose car adapter already, but am working on a system to reduce the humber of wires and devices I need to run. So far I have spliced the audio cables and charging cables into a Cat5, so there is only one cable and one plug to a Cat5 port I have mounted in my dash.

[sq_camry]

make sure you fuse it too

[inov8]

see:
http://www.powerstream.com/5-volt-index.htm

A dropping resistor is somewhat impratical with a 1.5A load because the power dissipated by the resistor will be more than 13 Watts when the engine is running.

[Luc]

Depending on how much current will be running out of the 5V point, you can use resistors to create a simple voltage divider network. Use this formula:

Vout = Vin * (R2/(R1+R2))

Make sure you use resistors with proper wattage, otherwise, they will burn out.

But it's always best to use an IC that does DC-DC regulation.

Do not use CAT5 as that's meant for low-voltage, twisted-pair, high-speed communication cabling. You're just asking for troubles if it melts from the current draw though the 24-26 gauge wires.

[drunken_panda]

I cam using cat5 because you can do Power Over Ethernet. I use a twisted pair for each the postive and negitive. I think I will end up using a car adapter hardwired in.

[JetspeedCamry]

Use an LM7805. 3 Pin 5 Volt regulator.

Pin 1 - 9-12V IN
Pin 2 - GND
Pin 3 - 5V OUT

And your done.

[nadir]

u can get an automotive power supply .. this one is designed specifically for 5v out only.

http://www.carnetix.com/P5V.htm

good luck

[JetspeedCamry]

Originally Posted by nadir

u can get an automotive power supply .. this one is designed specifically for 5v out only.

http://www.carnetix.com/P5V.htm

good luck

Thats basically a 7805 reg (or similar)..just with some wires and it's designed for another circuit... easier to make one..costya like, $1 or so to make!