Got a gizmo I want to run ... sept it wants 5v to run, not 12v (basically comes with one of those 240v plugs that has a 5v power output female connector).

So how to I get 12v down to 5v - with a resistor or something ---- jaycar? what gizmo.....

Cheers

a step down transformer or power regulator

Dick Smith sell 3 pin voltage regulators that will do what you want. They are only rated at 1 amp so will only run a device with a small current draw.

LM 7805 CT +5V 1A V/Regulator $1.20 each

Cheers!
Toby

cheers for that...

In the Data section of the Jaycar catalogues, you will find some really simple power supply circuits where you can use an LM7805 kind of regulator that you can bias a 2N3055 power transistor to make yourself a pretty much bulletproof and high powered regulated power supply if you need more than about 1 amp continuous.

The circuit is really basic and there are just a handful of parts needed and all the info you need to make it is in that section of the catalogue.

L8tr
E

i bought one of those DC to DC converters from cheap skate auto to run my hands free and it was the biggest pos i ever bought
its suposed to drop 12 volts to either 1.5, 3, 6, 7.5 or 9 but it to is only good for 1 amp

Joel

I made a dc to dc conveter for a mate to run a ps2 slim line; I used a few voltage regulators in series (or was it parallel?) I think the draw was fairly large like 9 amps or something I just mounted them to a heat sink in a little kit box. From memory you could use a resistor if you know for a fact that it will only draw a consistant amount of current and that the input voltage is always the same.

Firstly look at the item you are wishing to run. Next work out how much current it will draw maximum. Most to the items you will be wanting to plug into such a supply will be under 2 amps. Your best bet willl be to design and build a unit to do it for you as per discussion Tassupervee has raised. this will give you a better outcome and something robust. I would also build it in such a way that you cannot plug it in backwards and thus reverse polarity it. This can be exceptionally bad. Always fuse BOTH the input for the device as well as the feed to your supply. this will protect both the unti you are plugging in and also your power supply.

If your looking at current under 1amp then a simple variable cig lighter socket type device may fit your requirements. just means that you will need to fit a cig lighter so that the supply can be plugged in. This will also give you the added bonus of plugging other 12V cig adaptors etc (like phone charger, or portible dvd into the socket).

Cheers

T

PS: What is the device you are wishing to run??