Voltage question, am I missing something?

Ryan · Post by **Ryan** » Wed Dec 01, 2004 7:19 pm

I have seen suggestions for people using 7.2V batteries to power their portable N64's. Please correct me if I am wrong, but the N64 power supply outpts 3.3V and 12V. How do you get 7.2V to 12V?

Post by **Sparkfist** » Wed Dec 01, 2004 7:27 pm

The 12v line goes to a 7805 regulator mounted on he mobo. The 7805 needs at least 7v to work properlly, another thing is with a lower voltage going in to the regulator it will bleed off less heat so you wont have the same heat problems that Nintendo has as a result of having 12v going in.

JackFrost22 · Post by **JackFrost22** » Wed Dec 01, 2004 7:42 pm

you can also replace the regulator with an ldo and only input 6v

HK-47 · Post by **HK-47** » Wed Dec 01, 2004 8:08 pm

Also ldos create less heat because you are putting in less volts.

JackFrost22 · Post by **JackFrost22** » Wed Dec 01, 2004 9:03 pm

or a 5 volt switching regulator saves like 150mah

Ryan · Post by **Ryan** » Thu Dec 02, 2004 1:16 am

Any suggestions on how to get down to 3.3V from 7.2V?

Thanks so much!

JackFrost22 · Post by **JackFrost22** » Thu Dec 02, 2004 5:35 am

gamelver said somthing like a 10mhz resitor. I dont know if its right tough

HK-47 · Post by **HK-47** » Thu Dec 02, 2004 3:01 pm

Same way. A ldo or regular regulator, a dc-dc converter, and im not sure but maybe the resistor thingie...

Post by **Gamelver** » Thu Dec 02, 2004 3:30 pm

the method I used for my N64p4 was to get a 7805 that's capable of outputing atleast 2 amps (I used two in parellel) and added a resistor to it. Here's a diagram of it, although it's been posted before, so please search around before you post. I'll show it to you anyway though

:

so basically, I'm using the 7805 to ouput a constant voltage, then using the resistors to lower it to 3.3v. worked fine for me, and if you decide to try it, hope it does for you too

!!!!!!!!!
also, any car adapter or dc-dc converter would work fine too, just make sure it's capable of at least 1.5 amps, and 3.3v would be better than 3v.

someone · Post by **someone** » Thu Dec 02, 2004 7:16 pm

you must be doing something funky, becuase resistors are for lowering current and not voltage!

Post by **SpongeBuell** » Thu Dec 02, 2004 8:33 pm

someone wrote:you must be doing something funky, becuase resistors are for lowering current and not voltage!

No, they're for lowering voltage. Current isn't created or destroyed. Trust me, I took an electronics class and am learning about electricity in Physics.

MM007 · Post by **MM007** » Thu Dec 02, 2004 8:46 pm

So... of the energy you put into the system, sans screen, how much of it is used and how much is simply burned off?

Post by **Gamelver** » Thu Dec 02, 2004 9:06 pm

not sure what you're saying.....of the energy put into the 7805s? or the actual N64?.......anyway, I guess the enrgy burned off is the 7.2v to 5v........
just wanted to say that that circuit may be a bit faulty, if the draw of the 3.3v line drops down really low for some reason you'll fry the N64, and if the draw goes too high, it'll reset. If I can find time I'll test the draw of the 3.3v line for at least 30 minutes or so and see if the draw changes much. hope it doesn't.......

Post by **Sparkfist** » Thu Dec 02, 2004 9:12 pm

You know if that is 2 7805 regulators then they go to regulators, its almost just like the PSU. The only differece I can see is that the PSU has the 3.3v line going through about 2 capasiters.

someone · Post by **someone** » Thu Dec 02, 2004 9:47 pm

im pretty sure its POWER that isn't destroyed.....