How to reduce amperage?

[jefferam]

Hey everyone, I'm new to this board but seems like a good place to start.
I am working on a little project here.
I have a small tft lcd screen which is 12 V DC and i can't find the amperage but i am assuming around 300-500 mA.
i also have a camera which is 12 V DC and no more 300 mA
They are suppose to be for backup camera on a car.
I however want to wire this up in a boat and try to use it as an underwater camera.
I plan to attach them both to the same 12 V car battery which i will have in the boat.

What i need to know is how do i reduce the amperage? can i plug this directly on the battery or do i need to reduce the amperage first?
Will the appliances only draw what will be needed or will they get fried cause too much amperage is getting passed in?

What would be recommended?
Thanks

 

[lilimike]

You just need to worry about supplying the right voltage and making sure the battery can provide enough current for the load so you wrote your answer within your question:

the appliances only draw what will be needed

Mike

 

[jefferam]

Thanks, thats what i thought it was but since i wasn't 100% confident i just wanted someone to confirm it first.
So I'll try plugging it strait on the battery.
THanks.

 

[Boncuk]

Thanks, thats what i thought it was but since i wasn't 100% confident i just wanted someone to confirm it first.
So I'll try plugging it strait on the battery.
THanks.

A fuse won't hurt!

 

[Sceadwian]

jefferam, I think someone asks that very same question at least once a month here =)

 

[audioguru]

A car battery can supply nearly 1000 Amps to turn over a freezing engine in winter but the clock in the car takes only a few mA from the same battery with nothing reducing the current.

The electricity generating station that feeds mega-Amps to my city also drives my clock radio with nothing reducing the current.

 

[Reloadron]

i also have a camera which is 12 V DC and no more 300 mA
They are suppose to be for backup camera on a car.

I have a question on the camera. My truck has one that someone installed that is wireless. The camera is powered off the backup lights. Place truck in reverse and the camera comes on. However, the signal is transmitted wireless to the receiver. If the camera you have is similar I tend to wonder how well it will transmit underwater.

Ron

 

[Sceadwian]

It won't work wirelessly, I don't think it'll take too many feet of water to block a 2.4ghz signal most of them are 2.4ghz or higher (higher is worse). However if this is from a boat I'm guessing he's gonna be running a rope from it might as well run power so it doesn't have to be run off a battery, and might as well run a micro coax cable with it for the video signal, doesn't take much to pop one of those suckers open and solder coax where the antenna lead is, you can use a half wave whip antenna at it's other end using a coaster sized piece of metal as a ground plane within a few inches of the receiver for more distance over the cable than you'd ever get over freespace.

 

[Reloadron]

It won't work wirelessly, I don't think it'll take too many feet of water to block a 2.4ghz signal most of them are 2.4ghz or higher (higher is worse). However if this is from a boat I'm guessing he's gonna be running a rope from it might as well run power so it doesn't have to be run off a battery, and might as well run a micro coax cable with it for the video signal, doesn't take much to pop one of those suckers open and solder coax where the antenna lead is, you can use a half wave whip antenna at it's other end using a coaster sized piece of metal as a ground plane within a few inches of the receiver for more distance over the cable than you'd ever get over freespace.

Yeah, just thought I would mention that if it wireless I doubt you will see smiling fish looking up.

Ron

 

[Sceadwian]

It's a good catch reload, I didn't notice. It's not difficult to overcome but if you expect results with an actual wireless signal you're right, you'll be banging the side of the set and someone will fall overboard trying to get the antenna into the right position hanging over the side of the boat I can see it now.... "Hun a little to the left" <splash> "Hun?"

If your girl/wife isn't a fishing woman please replace 'hun' with the name of your fishing buddy.

 

[Reloadron]

It's a good catch reload, I didn't notice. It's not difficult to overcome but if you expect results with an actual wireless signal you're right, you'll be banging the side of the set and someone will fall overboard trying to get the antenna into the right position hanging over the side of the boat I can see it now.... "Hun a little to the left" <splash> "Hun?"

If your girl/wife isn't a fishing woman please replace 'hun' with the name of your fishing buddy.

Off topic side note. The one I have came with the truck. I got it from a coworker and he installed it thinking his wife would drive the truck. Forget it. I removed the receiver from the dash and now it lays on the floor. The kicker is all sorts of video is picked up by the thing. Baby minders, you name it. People do the damdest things with those surveillance cameras and don't realize the video is out there for the world to see.

Ron

 

[Sceadwian]

Off topic side note. The one I have came with the truck.

Wife? Those come with trucks now? I'm driving the wrong type of vehicle!

Our 2010 Sentra has a CCTV rear view, very handy. The wife likes it too, I use it more though =)
CCTV is crisp and realtime, I can understand the wireless noise and latency being an issue but with CCTV you're skipping a translation encoding decoding and probably another translation stage. I'm visually sensitive to anything that isn't subMS realtime, I prefer the CCTV to the reviwer mirror, the field of view is clearer =) I still doubt it but only because it's a wide field lense (partial fisheye) so the depth of field and distance is different than human vision. If you compare the field of vision a human being has even if turned around or through a reviwer mirror the backup cameras if well designed are awesome.