A few basic questions from a potential portable N64 maker

Post by **marshallh** » Sun Feb 26, 2006 8:21 am

1. The N64 can run on 3.3v and 7.2-20v.

2. If the dc-dc convertor stops, it doesn't hurt anything besides freezing the n64.

3. The psone screen pretty much needs 7.2-8v. What I'm doing is using a 7.2v battery to run the screen and n64 directly, and running it to a dc-dc converter as well.

4. I'm pretty sure european PAL n64's can be rgb modded. I may be wrong, though. I've been pretty satisfied with the composite video, because the psone lcd has a pretty decent signal decomber. But if you can get RGB output, go for it.

daguuy · Post by **daguuy** » Sun Feb 26, 2006 9:52 am

What does the unregulated current straight from whatever battery pack you use power in the N64? Are there likely to be any long term effects on whatever is powered by that due to over/under volting from high voltage/flat batteries?

that powers the audio/video or something like that. it goes threw a 7805 on the N64 so it is regulated and can take anything from 7.2v-30v

Also, when the battery's voltage drops below the operating range of the dc-dc converter (that regulates its input to 3.3v for the cpu), I assume the converter just 'craps out'. Isn't this bad for the cpu to have its source of current cut off without warning?

that's exactly what the N64's power switch does, not a problem

Wouldn't a portable LCD screen like the PS1 one also need a regulated power supply? according to the diagram here http://benheck.com/phpBB/viewtopic.php?t=9809 it doesn't, which I find a little odd. I had expected it would be very picky about what voltage it's working on.

it's not to picky, it works with 7.2v-9v

Also, Has anyone been very dissapointed with using only a composite connection to thier screen? I am living in Australia, so we have PAL N64s (Which aren't capable of being RGB modded apparently). My only other option is to get an NTSC N64 off ebay but then I can't buy games over here.

composite is your only choice with N64. the RGB mod gets a very weak signal and the whole amplifying thing brings down the quality so it's not worth it. composite isn't too bad.

Edit: Everyone seems to use a regulator to drop thier 7-14 volts worth of current straight from the battery to 3.3v for the cpu. I did some very technical research (looked at the bottom of the N64) and as most people have said, the CPU draws the most current (assuming you LED mod your screen) Would it be possible to run the N64 and screen at an intermedium voltage between the N64's 12v requirement and the ps1 screens 5v (I think) requirement, say 8.5 volts? I guess this depends partially on my first question. If this is possible, then having a bunch of batteries in parallel totalling 3.3v with a high current and a converter to step that up to 8.5v for the screen and other half of the N64 would be more efficient wouldn't it?

that would take a whole lot of amps from a lower voltage power source to to that. if you get a battery the right voltage for the screen and use an efficient dc-dc convertor to step it down to 3.3v (and maybe 5v if you bypass the 7805 on the N64 but nobody has tried that before) it'll be more efficient. plus most high capacity batteries are higher voltage than 3.3v

here's aguide for making a portable N64 if you need it.

timmeh87 · Post by **timmeh87** » Sun Feb 26, 2006 10:31 am

just to clarify, the psone screen and the nintendo 64 have their own voltage regulators onboard. the 64 only has it on the 12v input though.

without a lot of measurments and math, i dont think i could say for sure that using a 3.3v pack and stepping it up would be more efficient that what most people around here are doing. its not nessecarily going to be terribly inefficient though, and i am actually considering this as one way to power my portable (which is, as of yet, still wall-powered). you still do have to worry about the 3.3v line though (needs to be regulated)

also, the nintendo 64 has s-video out, and im almost positive theres an s-video mod for the psone screen.

Post by **Gamelver** » Sun Feb 26, 2006 11:48 am

the s-video mod doesn't really work, though, since the luma/chroma signals are connected in the chip

.....

anyway, a 3.3V battery pack might work pretty well (though I've never seen a 3.3V battery pack...). you would only need to step it up to 5V for the N64 and the psone screen, and then 7.2V for that one component on the psone screen that requires 7.2V

...can't remember which....

Post by **marshallh** » Mon Feb 27, 2006 7:37 am

You can use the TI DC-DC converters on 7.2v, I've done it myself, and the N64 ran fine on it.

timmeh87 · Post by **timmeh87** » Mon Feb 27, 2006 10:28 am

https://muss.cis.mcmaster.ca/~bernast/img/nimh.gif

i took this data off of two of my "AA" nimh batteries in series. the point you are concerend about is when the line crosses 2.4v. as you can see, you get about 80% of your capacity before then.

Fanboy · Post by **Fanboy** » Sat Mar 04, 2006 10:25 am

You actually don't need the expansion slot for anything... The actual points for cart-slot connection are on the board itself... The cart-slot does lead into the expansion port though... Who knows? Perhaps for some unreleased add-ons

?

timmeh87 · Post by **timmeh87** » Sat Mar 04, 2006 1:46 pm

the disc drive, acutally.

and youre right that you cant put a pine header into the all right holes, but you can put it into HALF of the right holes, then manually wire up the other half

theres something about it on my site. too lazy to link you.

timmeh87 · Post by **timmeh87** » Mon Mar 06, 2006 1:44 pm

if youre not good at soldering, that expansion pack isnt going anywhere.

even if you are, its not going there. you really cant be using wires to "move" it anywhere, ram is sensitive to things like the length of the wires, and in general theres just too many problems that will arise with trying to do it like that. if you plan to try to mess with the expansion pack at all, plan to break at least one nintendo 64.

it looks like you have sort of guessed at the size of things in a lot of places. it might not all go together exactly as you have planned... for example 12 AAs might take up more space than you think...

Post by **marshallh** » Mon Mar 06, 2006 3:05 pm

I've been thinking about the expansion pack slot, it may be possible to desolder the two metal contacts on the backside and bend it towards the center of the PCB. Then it would be facing 90 degrees, as long as you took off the RAM "heatsink".
I'm going to try this soon on a junked n64 I have, but I though I'd throw this out there.

Post by **Gamelver** » Mon Mar 06, 2006 3:26 pm

hmmm....might be possible, but the contacts might break

....if they don't, it'd be a great way to save space

.

timmeh87 · Post by **timmeh87** » Mon Mar 06, 2006 8:43 pm

or just do what i did

timmeh87 · Post by **timmeh87** » Tue Mar 07, 2006 3:33 pm

yeah i finished the ram thing...

took off the slot and stuck the circuit board from the pack on.

Post by **Gamelver** » Tue Mar 07, 2006 4:47 pm

crappy picture but....looks good

!

works and everything?

timmeh87 · Post by **timmeh87** » Tue Mar 07, 2006 5:09 pm

it did. then i took off the cartridge slot... and banged it around a bit... hopefully it will still work when i get it all back together.