Voltage Reducing

[coastergeekrtc]

I have made a custom roller coaster model from wood and other materials found at hardware stares. To keep my coaster lit I used two battery powered Christmas lights sets. To power just one of them I use two C batteries. Together they make 3v. I am trying to hook them both up to my wall socket (120v). I know that I have to use a transformer but I do not know what type or anything else. Can someone please show me what I need to do to make this?

 

[Russlk]

What you want is a "filament transformer" 120 VAC to 6.3 VAC center-tapped. It will most likley be described as: 120/6.3ct. The secondary will have 3 wires, use only two: the center tap and one other which will give you 3.15 VAC.

 

[coastergeekrtc]

How would I hook it up? Do I just cut off the battery holders and take those four wires(2 per light set) and connect them (positive to positive and negative to negative)? Then do I attach the positive and negative from the wall.? Where do I hook up the center tap, to positive or negative and do I hook up the other wire to the other one? Sorry for all these questions but I am just confused. And where can I buy this at? Thank You for your help.

 

[stevez]

The filament transformer is a good start but whatever you do, be careful.

On the 120 volt side you need to be sure you address any shock hazards. That may be obvious but we don't know what you know based on the limited discussion so far. Make sure the power cord used is heavy enough so that if there is a short circuit in your supply that it will trip the breaker. A cord that is too light may not trip the breaker or blow the fuse if there is a short - it will get hot and burn. When I was in London a few years ago it appeared that regulations there addressed this a little better than we do here in the US - just my opinion.

If I were doing it I'd fuse both the primary (120v) side and the secondary (6.3v) side. Unless you know the transformer will sit there comfortably with it's output shorted I'd strongly recommend this. Fuse size on the secondary should be governed by current carrying capacity of the wires being powered. A pair of 'D' cells can make wire that is small enough glow red hot and start a fire.

As an alternative, you might consider making use of a power supply "wall wart" - the black cubes that plug directly in to the outlet. There's a large measure of safety that's already addressed. Much of the dangerous stuff is all done and contained within that black cube. If you have something that is a little to high in voltage we can help address that as long as it can deliver enough current. You might be able to purchase what you need directly as well.

Keep coming back, we'll help you thru this. Good luck.

 

[coastergeekrtc]

Where can i get this wall wart and what exactly does this do?

 

[stevez]

The "wall wart" is used to describe the relatively common power supply "cubes" that are supplied as AC adapters for radios, CD players, battery chargers, etc. They are also used on lot of things that do not consume a lot of power. Here in the US you can purchase them all over the place - Radio Shack, KMart, etc. They can also be purchased via mail order. Look at Jameco website and search on power supply - you'll see what I mean.

The "wall wart" can supply AC or DC - I've got plenty of each. They all have transformers and if DC they have rectifiers in them. Some have regulators in them as well.

 

[coastergeekrtc]

Is this what you mean? Just it would be for an american outlet.