Power supply

Post by **gannon** » Sun Apr 18, 2004 6:51 pm

I was checking out the n64 power supply today, and I noticed that the 12V line is actually around 11V, and when there is a load present, it runs at around 9.7V.
What I find strange about this is that the gamecube screen seems to require 12V, but runs fine off of the n64 12V line (which runs at around 9.7V). I know that it doesn't use 5V from a 7805, but it might run on some different voltage, like 7V or something.
Any ways, knowing that the 12V is actually around 9.7V means that the n64 should run off of 1 9.6V rc battery or a laptop battery instead of 2 7.2V rc batteries, or even less AA batteries, like 8 rechargables instead of 10.

Post by **Gamelver** » Sun Apr 18, 2004 6:59 pm

Yeah it does run off of 8 rechargable batteries. My N64p uses 8 Nimh rechargable batteries and it runs for about an hour and 20 minutes.
I might actually add a couple batteries just to add to the battery life but 8 definitlely works.

Post by **gannon** » Sun Apr 18, 2004 8:10 pm

Yeah, its nice that it only needs around 10V to run instead of 12V. Even though its a small difference, when buying batteries it can make quite a large price difference.

MR.MOD · Post by **MR.MOD** » Tue Apr 20, 2004 5:59 am

The 12v line connects to a surface mount 7805,You could buy a low drop out 7805 and run the 12v line on anything from 5v-30v.
If you trace the 12v line on the n64 board you'll find out that it goes to the 7805 which lowers the voltage to 5v.

Post by **gannon** » Tue Apr 20, 2004 12:28 pm

Yeah, I know it goes to a 7805, but I also know that it goes to a few other points on the board before the 7805.

MR.MOD · Post by **MR.MOD** » Tue Apr 20, 2004 4:26 pm

It runs fine on my infolithium 7.2 volts. I think it should run fine on 5v. I'll try it.

Post by **gannon** » Tue Apr 20, 2004 5:16 pm

hmmm... strange, even though it runs to the 7805, the 12V line continues past it into a capacitor, but then the capacitor empties into ground.
Oh well, who cares as long as it works....
At least this means I won't have to burn up all that extra wattage from using 12V. Its kinda a shame that some of this stuff isn't recorded more, I've seen plenty of people using 12V when they don't need it, and then have low battery life and overheating....
If I do order from digikey soon, I'll buy a 5V ldo and a 3.3V ldo. Otherwise I'll just make a power supply from 2 3V regulators from radio shack.

Oh, and an update on my n64p. So far I've umm.... broken 2 n64s!! yeah, the 1st one was done, then I dropped it and it broke, then just recently, I was working on the 2nd one and I broke the cartridge port. I think that I've decided to leave the cartridge port where it is for now..... I should be able to pickup a new n64 pretty soon, so for now I'll work on the controller. Also, the port for the memory card is hard to move, so I'll be chopping up my controller soon and adding tactile switches to it. Hopefully I'll get the main board small enough so I can put it sideway in the case so the memory card port sticks out the bottom.

Guest · Post by **Guest** » Tue Apr 20, 2004 5:30 pm

Yeah I broke two N64s too

. When I finally got one that wasn't broken and put all the wires in with the controller, there were problems with the controller so I had to take everything out, fix it, and put it all back in.

I made sure everything was fixed and soldered well before I put it all back in and haven't had any problems since(well except when I overcharged it once but that was easy to fix)

Post by **Gamelver** » Tue Apr 20, 2004 5:32 pm

Oops I forgot to sign in

stereth · Post by **stereth** » Thu Apr 22, 2004 7:44 am

gannon wrote:the 12V line continues past it into a capacitor, but then the capacitor empties into ground.

This is called decoupling. It charges up a capacitor to whatever the supply voltage is. When the processor needs a sudden burst of power, it pulls from the capacitor instead of trying to suck more current from the power supply. As long as the DC sits on the cap, no power is going through it.

Read up on LDOs before using them. I've heard they can be harder to use than standard voltage regulators.

loverare · Post by **loverare** » Thu Jun 14, 2007 2:42 pm

Hey guys, I don't understans the "7805". What that, its important .

jeroen · Post by **jeroen** » Thu Jun 14, 2007 2:57 pm

7805 is pretty important here. It bumps up to around 32v into 5v.

Post by **gannon** » Thu Jun 14, 2007 3:54 pm

So old, so stupid

timmeh87 · Post by **timmeh87** » Thu Jun 14, 2007 6:51 pm

yeah, man. I was reading it and thinking "gannon should know about decoupling caps! and that the 12v line will work on 7.2v!" and then I realized its 3 years old

loverare · Post by **loverare** » Fri Jun 15, 2007 8:08 am

Okey but what that. It is a component