Here is a cheap and easy 3.3v converter!

jeroen · Post by **jeroen** » Fri Jun 22, 2007 4:23 am

Dude if your running it. HEATSINKS ON IT NOW!

bacteria · Post by **bacteria** » Fri Jun 22, 2007 4:34 am

I disconnected it from the power supply after 1-2 minutes use - didn't want to fry the mobo!

I need to see if I have any old heatsinks about I can hack and shorten, if now I will have to buy some (can't do much on project until then really).

Thanks for your concerns!

I am hoping someone might comment on my thoughts on hacking the original piece of metal which went on top of the N64 chips - if I cut it down a bit, made holes in it too, if that would give enough surface area to keep the chips cool, with a fan directly above blowing onto this metal - would 1) save me money, and 2) keep things flatter. Anyone tried this?? Nintendo used this as the heatsink after all on the N64, larger surface area (top and bottom) as no fan - if you used a smaller surface area and a fan, that would compensate - the heat disipates onto the metal sheet after all.

timmeh87 · Post by **timmeh87** » Fri Jun 22, 2007 2:59 pm

oh. yeah I gave my opinion on heatsinks on the other thread. I still think you should just grab something like this:

http://www.cpu-world.com/CPUs/5x86/S_Cy ... tsink).jpg

saves you a hell of a lot of dremelling.

also, the whole point of the dc-dc converter is to cut down on the current draw from your power supply. lets do some math right now!

the converter allows you to draw the same amount of power at another voltage. (power for the uninformed is volts * amps)

so we have the 3.3v line drawing 1.5A lets say. thats 3.3*1.5 = 5W. now its only 80% efficient, so we will be drawing 5/0.8 = 6.25W from the power supply.

the power supply is 7.5V lets say, so the current would be 6.25/7.5 = 0.83A. a little more than half as much!

in reality, my system (both lines!) draws about .7A with a dc-dc at 7.2v. of course my converter is like 95% efficient.

bacteria · Post by **bacteria** » Fri Jun 22, 2007 3:24 pm

Thanks for the calculations, a bit over my head, but thanks!

Ok, in other words, it is drawing less than I thought, which is only a good thing. It doesn't really matter if it takes a bit more draw or not, it is running on mains and not batteries. It means the mains adapter will stay nice and cool - and it works

bacteria · Post by **bacteria** » Tue Jul 17, 2007 1:38 am

Thought it worth a final update on this thread before it lays to rest.

The car adapter I am using (designed to power a Sony minidisk apparently), is running fine. I have it working on my N64 project, connected to the PSone PSU, running a controller and memory pack, fan and LED's. No reason it also won't drive the motor(s) for the rumble pack too (optional). System fires up first time (assuming you use electrical wire to connect power from the PSU and the car adapter to the N64 mobo and not thin wire, as I tried, in error).

Proof of concept was fine, it works. Downside is that you can only use the car adapter if running off mains power, batteries can't work with the car adapter.

I get about 7.26v - 7.28v on the main line and about 2.76v - 2.79v on the other line by using the PSone PSU (which is 7.5v, 3amp) and car adapter. Not great voltages, but sufficient to run the N64 system ok. I have tested this now on two N64 mobos, both fine. I have tested a variety of game carts too, and they run fine.

Using the TI board is of course preferable as you can use batteries too, however if you can't get one yourself (as I couldn't) the car adapter provides an easy-to-get-hold-of alternative.