# 36v to 12v

#### demonkid

Joined Mar 26, 2006
4
ok i want to convert 36volt @ 9 watts to 12 volt's
where would i get a converter at and 1 more ?
if i did convert the 36 volt to 12 volt wouldent the amount of watts go up also since i am
going down in voltage.

#### Papabravo

Joined Feb 24, 2006
20,411
Originally posted by demonkid@Mar 27 2006, 12:21 AM
ok i want to convert 36volt @ 9 watts to 12 volt's
where would i get a converter at and 1 more ?
if i did convert the 36 volt to 12 volt wouldent the amount of watts go up also since i am
going down in voltage.

[post=15478]Quoted post[/post]​
If the power went up you would have created a device with greater than 100% efficiency, aka a perpetual motion machine. In any conversion scheme power in will always be greater than power out. Do you want to buy one or build one?

If you are buying one , assume you had a converter that was 80% efficient. 36 Volts and 9 Watts is 250 milliamperes. 9 Watts times 0.8 is 7.2 Watts. 7.2 Watts divided by 12 Volts is 600 milliamperes.

So when you drop the voltage there is more current available but there is always a power loss. Where does that 1.8 Watts go? Up the chimney mate, it's lost and gone forever as heat.

#### david mendes

Joined Mar 23, 2006
6
If you mean AC, a transformer 3:1 will do...
If you mean DC, find 7812 chip and a couple of capacitors to put on IN and OUT pin.
David Mendes

Joined Jan 10, 2006
614
Lets assume your talking DC voltage here....

I also think you may mean "Amps" or current, not the "watts" going up.
If you use a Switch Mode regulator/converter, then yes, you should end up with more current, and only a slight reduction in the "Wattage" (i.e high efficiency, low power loss).
If you use a linear regulator such as the 7812 then you will get no increase in current, as 2/3 of your "Wattage" (Power) will be wasted as heat in the regulator. It will get real hot, and need to be mounted on a heatsink so that all that wasted power can be used to warm up the box it's all mounted in... i.e. it will be Inefficient, and with 36v going into it, will be running at (or possibly above) it's maximum ratings.

#### demonkid

Joined Mar 26, 2006
4
yea i am talking about dc voltage

Originally posted by Gadget@Mar 27 2006, 06:14 AM
Lets assume your talking DC voltage here....

I also think you may mean "Amps" or current, not the "watts" going up.
If you use a Switch Mode regulator/converter, then yes, you should end up with more current, and only a slight reduction in the "Wattage" (i.e high efficiency, low power loss).
If you use a linear regulator such as the 7812 then you will get no increase in current, as 2/3 of your "Wattage" (Power) will be wasted as heat in the regulator. It will get real hot, and need to be mounted on a heatsink so that all that wasted power can be used to warm up the box it's all mounted in... i.e. it will be Inefficient, and with 36v going into it, will be running at (or possibly above) it's maximum ratings.
[post=15486]Quoted post[/post]​

#### windoze killa

Joined Feb 23, 2006
605
Originally posted by demonkid@Mar 28 2006, 12:05 AM
yea i am talking about dc voltage
[post=15494]Quoted post[/post]​
Powerbox, Amtex and Lambda all produce modules that do exactly what you want. Havwe a look at their web sites.

#### demonkid

Joined Mar 26, 2006
4
Originally posted by windoze killa@Mar 27 2006, 05:24 PM
Powerbox, Amtex and Lambda all produce modules that do exactly what you want. Havwe a look at their web sites.
[post=15498]Quoted post[/post]​
thx and could you give me the links to the web sites? i'll google them but if i cant find them i wanna have something to come back to

#### windoze killa

Joined Feb 23, 2006
605