Modifying a Saturn's Clock and Internal Ram to draw power from mains

[Chizzles]

Right, well, I'm sure there are people out there who have always thought "I cannot be arsed buying a new CR-whatever power cell".

So I had this brain waive (If I have a brain, that is), anyone think it possible? (well of course it's possible)! Just not 100% sure how to tackle it.

I would appreciate any light anyone has to shed on the subject   On the best method for it

Cheers ^_^

[l_oliveira]

It might sound weird, but it already has a circuit to power the real time clock and sram while the system is on (without need the battery).
That's what allow you to turn on the saturn and swap the battery with it on, keeping the ram contents while you exchange the battery.

To do what you want (have it to keep the data with the game system off) you would have to build a second power supply and have it aways on. I would suggest 3v applied directly to the battery connector. Anyway, Microsoft tried something like this using an "Aerogel" capacitor (1 farad) that could keep the system clock powered for a few hours without power on the mains. But XBOX follows the PC-AT design which requires a standby secondary power supply.  So you see, it had a "ever on" power supply to begin with. That doesn't happen with the Saturn.

I would say that it's not worth the hassle, but on other hand I would like to know what you or anyone else would do to "fix" this issue .... lol If you have any thing I can help with, I'll try to:)

[kendrick]

If the end goal is to have persistent Saturn save data, the best way is to use an official RAM cart or 4-in-1 cart. But if you can't stand having to set the clock every time you power up, then alternate power is necessary.

However, I can't see that it's practical to test and to build a regulation circuit that will correctly power the memory portion of the Saturn without conflicting with other power draw sources internal to the console. In your place, rather than trying to reinvent the wheel I'd just run new power leads to an external battery. Two AA cells would last for ten years and be a perfectly workable substitute.

[phreak97]

yeah, do that.. make up a battery pack that fits in the expansion bay. you can put in more than two aa's, if you wire it right itll still be 3v (two sets of two in parallel if you use four batteries), then close it up and forget about it forever.


alternatively cr2032's are about $10 for 25 off ebay if you want to stock up:P

[kyuusaku]

You could always replace the CR2032 with a rechargeable battery and slowly charge it from the main supply.
The diode between the battery and RAM could be removed on the rechargeable circuit too if you don't add any other current sources which could charge the battery. Besides the battery all you need to preform this mod is a diode and 1K resistor connected in series from the 5V line to RAM VCC. If rechargeable coin cells exist, that would make it even easier. Also depending how the power LED is wired, maybe you could rework it so that the LED current charges the battery so then all you'd need is a wire and battery...

[l_oliveira]

Now, that's a great idea

It would last for a while, not ?

I like the Sanyo rechargeable batteries SEGA used on the Dreamcast. I had a friend who live in Japan buy me a bunch of them in Akihabara and mail me. The stuff I built with them in 2001 are working fine to this day.