12v power supply?

[Ian H]

I'm pretty new to electronics but i want to start making some LED related bits for cars. problem is i want to test them to see if they work before they go in the car. So question is where do i get a 12v power supply from?

[Steve_hi]

http://www.electronics-lab.com/projects/power/009/index.html

Build It ;D

[Ian H]

:-\ slightly out of my league! i don't even know what most of the symbols mean!!

[audioguru]

If you know nothing about electronics then use 8 AA alkaline battery cells in series. It will make 12V when the cells are new.

[ante]

Hi Ian,

Three of these in series: http://www.gear-zone.co.uk/eshop/Duracell-45v-Flat-Battery.html
will supply 13.5V which is close to what you have in a car. For testing LED circuits they will probably last for years!  ;)

[supervisor]

Hi,
Find yourself a +- 220v/12v transformer capable of handling 200ma, a 1a bridge rectifier, and a 1000mfd 25v electrolytic capasitor and a piece of veroboard. Over a switch and a fuse take the 220v to the transformer with the rectifier in serie and the cap in parrallel you should get a bit more than 12v to power your LED's. But I must warn you The mains supply of 220 volt is very lethal. If you know nothing about power electronics leave it alone and rather go and buy yourself a comercial power supply that is capable of handling the power of LED's. The current of smal led's is a couple of mA and bigger ones do not need a lot more. Enjoy!

[ante]

Hi,
Find yourself a +- 220v/12v transformer capable of handling 200ma, a 1a bridge rectifier, and a 1000mfd 25v electrolytic capasitor and a piece of veroboard. Over a switch and a fuse take the 220v to the transformer with the rectifier in serie and the cap in parrallel you should get a bit more than 12v to power your LED's. But I must warn you The mains supply of 220 volt is very lethal. If you know nothing about power electronics leave it alone and rather go and buy yourself a comercial power supply that is capable of handling the power of LED's. The current of smal led's is a couple of mA and bigger ones do not need a lot more. Enjoy!

This solution will supply about 17V at low load! This could damage LED

[Ian H]

would this be ok:

http://cgi.ebay.co.uk/2-pack-of-AA-Battery-holder-8xAA-12v-with-PP3-clip_W0QQitemZ280054793903QQihZ018QQcategoryZ7285QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

?? some one above mentioned using 8AA batteries for a 12v supply? would it just be a case of cliping the +ive terminal to +ive wire/led leg and -ive terminal to -ive wire/led leg??

[audioguru]

would this be ok:

It is perfect for holding 8 AA battery cells to make 12V. But a charged and charging car battery is 13.8V.

?? some one above mentioned using 8AA batteries for a 12v supply? would it just be a case of cliping the +ive terminal to +ive wire/led leg and -ive terminal to -ive wire/led leg??

Yes.

[Ian H]

oh i thought it was 12v  ???

so does that mean i shouldnt be using 12v resistors too?  where can i find something that will hold the batteries Ante mentioned?

[ante]

You don

[jeeep]

Ian,
What I would do is get several old phone chargers. Lets say you have two phone chargers that puts out 6Vdc each. Take the positive from one and the negative from the other and check the remaining leads, which should equal 12Vdc. The power source doesnt have to be strickly old phone chargers, perhaps an old remote control car batter charger, etc. Oh yeah be sure to get a multimeter to check voltages!

[Ian H]

any chance of a quick diagram ante? i think i know what you mean but I'm probably wrong!

Ian,
What I would do is get several old phone chargers. Lets say you have two phone chargers that puts out 6Vdc each. Take the positive from one and the negative from the other and check the remaining leads, which should equal 12Vdc. The power source doesnt have to be strickly old phone chargers, perhaps an old remote control car batter charger, etc. Oh yeah be sure to get a multimeter to check voltages!

im having trouble under standing batteries, last thing i want at the moment is to be playing around with mains electric  :o :o

[Steve_hi]

If all you want to do is test them then just use a 12v car battery you will not have to do anything

[ante]

Yes a good chance! Is this what you need?

[Ian H]

Thanks alot ante, just what i needed  ;D ;D