The Retro64 Worklog. NEWS: Finished! Got nice pics!

deviouskoopa · Post by **deviouskoopa** » Sun Jan 04, 2009 9:02 pm

Pretty nifty USB multimeter

vskid · Post by **vskid** » Sun Jan 04, 2009 9:12 pm

Nice work, but you still aren't understanding amps right.
3.3v 1A isn't the same as 12v 1A. The 12v is almost 4x the power. 3.3v*1A=3.3W 12v*1A=12W
So in the portable, the 3.3v comes from a regulator. We'll say that the main battery is 7.2v. The regulator converts 7.2v to 3.3v. The N64 draws a bit over an amp of 3.3v. The regulator only needs about half that (since 7.2 is about 2x 3.3), so the regulator draws .5A from the battery. Its still the same amount of power, though.

Mario · Post by **Mario** » Sun Jan 04, 2009 9:17 pm

*Whoops, double post. See the post below this one*

Mario · Post by **Mario** » Sun Jan 04, 2009 9:19 pm

Ah, I get it now. Thanks.

So on a portable, if I measured the amp draw after the regulator, it would be 1A. Measure before the regulator, and it's .5A, because 3.3v is half of 7.2v. Thank you.

So that's even crazier - the N64 will only draw 600mA! Add an LED modded PSone screen and you get a total of 1A of draw. That means my batteries will power the portable for 6 hours, assuming full efficiency on the regulator's part.

bacteria · Post by **bacteria** » Sun Jan 04, 2009 10:00 pm

As I recall on my Multi project, an N64 with expansion pack, unmodded PSone screen gave just under 7 hours on Pokemon Puzzle League with 8800mA Li-ions. Based on that, you are looking at consumption of about 1250mA per hour. Some games need more amperage, some less. Based on this, 4000mA should work for just over 3 hours (my next project).

Mario · Post by **Mario** » Sun Jan 04, 2009 10:06 pm

I figured 1000mA, you got 1250mA; that extra 250mA is probably the regulator's inefficiency and other various bits and bobs, like the controller and memory card.

And yes, some games do use more mA than others.

bacteria · Post by **bacteria** » Sun Jan 04, 2009 11:23 pm

Mario wrote:I figured 1000mA, you got 1250mA; that extra 250mA is probably the regulator's inefficiency and other various bits and bobs, like the controller and memory card.

And yes, some games do use more mA than others.

Yes, there was a controller and memory card attached. The 3.3v was via a TI card.

Mario · Post by **Mario** » Mon Jan 05, 2009 6:59 pm

bacteria wrote:
Mario wrote:I figured 1000mA, you got 1250mA; that extra 250mA is probably the regulator's inefficiency and other various bits and bobs, like the controller and memory card.

And yes, some games do use more mA than others.
Yes, there was a controller and memory card attached. The 3.3v was via a TI card.

You also had a fan, if I remember correctly?

Here are some better shots of my testing setup. Here is my new multimeter hooked up:

The yellow alligator clip in the background is jumping the 12v line, because I am testing the 3.3v line right now, which is hooked up to the multimeter with the red alligator clips. The meter is showing 1.480 amps being drawn.

There is a close-up shot of the plug in the side of the N64.

bacteria · Post by **bacteria** » Tue Jan 06, 2009 2:41 am

So you say 1.48 amps without the 12v line; so about 1.6 amps? That seems higher than discussed before - especially as it only has Super Mario 64, which was not the most demanding game for amperage. Try Donkey Kong 64.

Yes, my system included a fan, which as I recall was either 20ma or 40ma.

Ben Cebhrem · Post by **Ben Cebhrem** » Tue Jan 06, 2009 3:44 am

6 watts, assuming 1.5 amps on the 3.3v rail, and 110ma on the 12v rail.

Comparing two different amp ratings at different voltages is like asking which is better; a shot to the gut, or a chance to be Jesus for a day? It's asking for trouble, and confuses the issue in a way that isn't needed.

Stick to watts then when explaining the overall draw, or break it down into the separate rails- otherwise people will get confused.

Mario · Post by **Mario** » Tue Jan 06, 2009 7:02 pm

bacteria wrote:So you say 1.48 amps without the 12v line; so about 1.6 amps? That seems higher than discussed before - especially as it only has Super Mario 64, which was not the most demanding game for amperage. Try Donkey Kong 64.

Yes, my system included a fan, which as I recall was either 20ma or 40ma.

It's higher because:
1. I have the expansion pack in
2. It is currently overclocked to 2.5x

Did you see my post near the top of the page? I did several tests about amperage draw. With DK64 at 1x clock multiplier (stock N64) the amp draw on the 3.3v line was 1320mA. With SM64, jumper pack, 1x multiplier the amp draw was only 1100mA. Before it was thought with the jumper pack the draw was 1.5A, and that games that needed the exp. pack drew 2.0A. It is really much lower, the expansion pack only adds like 220mA.

timmeh87 · Post by **timmeh87** » Tue Jan 06, 2009 10:45 pm

K let me add some points...

Only 'switching' or 'dc-dc' type regulators will conserve power like vskid was explaining. Im pretty sure that everyone here is using one to get 3.3v anyways. But if you are dealing with something like a 7805 then the same amount of current goes in as comes out - and you lose tons of power.

And yeah, IIRC ~700mA sounds about right for the N64 with a switching regulator. (running on about 7 volts with no sound hooked up... this was years ago though. I think I was running Extreme G in demo mode with an expansion pack in).

Anyways, these numbers you are giving us... what are they. Averages? Peak? Theres no way the current is holding steady at one number, if it is it you are probably looking at the menu and the test is kind of pointless anyways. The system is going to use more power when its struggling to crank out polygons, vs sitting on a static image. Id be curious to see what the power consumption is like during a 4-player round of perfect dark.

Mario · Post by **Mario** » Wed Jan 07, 2009 6:04 pm

Don't switching regulators cause screen interference?

And I took the averages of the amp draw. It wasn't on a menu, I was actually playing the game, going in to different rooms, walking around etc. It didn't change much, on a menu it went down 100mA or so. But during play, it fluctuated by about 70mA, those values are what they usually were.

Mario · Post by **Mario** » Wed Jan 07, 2009 8:25 pm

Hey! Guess what! I received my two N64s, a PSOne screen with power adapter, and an Instructables prize pack today. I don't have a camera right now, I'll update with pictures later tonight!

If you're wondering, I entered my NES Portable Instructable in a contest. Here are the final results: http://www.instructables.com/contest/batterypowered/

Even though my Instructable in 3rd, I got the most votes. 12 people got first, there was no runner-up prizes.

Mario · Post by **Mario** » Wed Jan 07, 2009 11:06 pm

Hmm, triple post. Is that bad? It must be okay if you have an update, right? After all, this is a WIP.

Well, I told you I got all my stuff. Here it is:

Two N64s and a PSOne screen. I opened the N64s, both have revision 3 boards, perfect for RGB modding. Here they are, uncleaned.

And the carnage it caused on my table: