NES Battery PCB

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Ice Man
Posts: 547
Joined: Fri Jul 04, 2014 2:34 pm

NES Battery PCB

Post by Ice Man »

I'm planning to make NES Battery PCBs to extend TSROM boards and convert them to either TKROM or TNROM. However, I lack skills and knowledge with Eagle or any other PCB programm.
I'd then like to submit the files to OshPark, Itead or any other good PCB production company with a reasonable price, preferably Oshpark anyway.

Anyway, if someone would be so kind and make the Eagle files for me so I can submit them and produce PCBs that'd be great.
Here's the schematic I came up with:

EDIT: Fixed Connection.
Attachments
NES Battery.png
NES Battery.png (3.74 KiB) Viewed 5694 times
Last edited by Ice Man on Wed Aug 05, 2015 2:40 pm, edited 1 time in total.
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: NES Battery PCB

Post by lidnariq »

That's ... confusing. And wrong.

Use this:
battery-switchover.png
battery-switchover.png (717 Bytes) Viewed 5702 times
Diodes are 1n914, 1n4148, or any other cheap signal diode (you only need ≈50mA ampacity), capacitor is >4µF.

Also, don't connect the CIC to the battery switchover circuit, it doesn't need it.

Given how simple this is, and the amount of rework needed on the PCB, it's kinda hard to justify a PCB instead of just a tiny bit of perfboard.
Ice Man
Posts: 547
Joined: Fri Jul 04, 2014 2:34 pm

Re: NES Battery PCB

Post by Ice Man »

Well, it doesn't need to be connected to CIC Pin 1 (which was wrong since it should be the 16th pin) but the original circuit from SNROM did that, too.
WRAM Pin 28 or any other VCC will work, too.


I know that perfboard works fine but I want to get started making PCBs myself and learn more about Eagle, so why not? :)
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: NES Battery PCB

Post by lidnariq »

Ice Man wrote:Well, it doesn't need to be connected to CIC Pin 1 (which was wrong since it should be the 16th pin) but the original circuit from SNROM did that, too.
No it doesn't. Did you confuse CHR RAM and PRG RAM?

Anyway, here's a corrected version of your schematic:
Attachments
NES Battery-errata.png
NES Battery-errata.png (1.3 KiB) Viewed 5679 times
Ice Man
Posts: 547
Joined: Fri Jul 04, 2014 2:34 pm

Re: NES Battery PCB

Post by Ice Man »

No, I had the board upside down. Brain error. :P
Thanks, that helps.
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FARID
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Re: NES Battery PCB

Post by FARID »

I think only one resistor is needed, so I suggest this one :
Attachments
WRAM_Battery.PNG
WRAM_Battery.PNG (1.9 KiB) Viewed 5640 times
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nintendo2600
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Re: NES Battery PCB

Post by nintendo2600 »

Farid has the best answer IMO. That is the method I also use.
Ice Man
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Re: NES Battery PCB

Post by Ice Man »

Alright, thanks!
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Jazzmarazz
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Re: NES Battery PCB

Post by Jazzmarazz »

Ice Man wrote:Alright, thanks!
Hey Ice man.
The diagram Farid Shared is what I have found existing on most official carts. It works but is not ideal since the carts do not contain a low-power reset IC like more modern carts. This is why Every battery backed cart for the NES demands that you hold the reset button down while powering off. As you know the Sega genesis carts for example, have the BA6162.

It does work though, so why over complicate it? :P
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