Questions regarding the NES power supply

SatoshiMatrix · Post by **SatoshiMatrix** » Mon Dec 20, 2010 9:39 pm

I've got a question about power supplies for the NES.

I got a NES-101 Toploader and I've noticed it runs a bit hot using the standard NES Power Supply.

I know the NES-001 and 101 both are robust systems that are use a Power Supply that outputs AC but I've also heard you can use a power supply that outputs DC as well.

Regarding that, I have a variable power supply where I can adjust the power supply to any number of settings and change the polarity.

So I have three questions.

1. Is it completely safe to use something that outputs DC 9v on either model NES? Does this put any extra strain on the system?

2. If I use a power supply that gives 9v DC, what polarity should I use? I've read that if a system expects AC input, any polarity DC will work. Is this true?

3. The NES is rated to run at 9v. To reduce excess energy loss to heat, could I use a power supply that provides 7.5v and expect results? What is the lowest I could go to power an NES?

kyuusaku · Post by **kyuusaku** » Mon Dec 20, 2010 10:24 pm

Yes you can use DC. DC puts less strain on the system because DC adapters have large capacitors in them so less ripple than with the NES' smaller cap.

It's safe to use any 9V DC because of the rectifier.

Because the NES has a rectifier, the input voltage drops 1.2-1.4V. The 7805 regulator requires ~7V to function so I wouldn't go lower than a 9V supply. With 9V there is quite little power wasted.

Post by **tepples** » Tue Dec 21, 2010 6:14 am

But how many amps does the NES need?

Bregalad · Post by **Bregalad** » Tue Dec 21, 2010 6:32 am

3. The NES is rated to run at 9v. To reduce excess energy loss to heat, could I use a power supply that provides 7.5v and expect results? What is the lowest I could go to power an NES?

True. The 9V adapter is a total waste of energy, it dissipates a lot of heat.
(the 7705 has to disspate 4 V * NES current consumption).

I'm pretty sure it'd work fine/better with 7.5 V adapter if you have one. Polarity doesn' matter because of the redresser.

peppers · Post by **peppers** » Tue Dec 21, 2010 7:59 am

so whats the voltage range can the nes safely run on?

Just out of curiosity would it be able to run off a car battery directly?

sorry if I'm hijackin the thread.

game-tech.us · Post by **game-tech.us** » Tue Dec 21, 2010 8:08 am

A lot of this thread is discussed in my power and heatresearch pages.

Xious · Post by **Xious** » Fri Dec 24, 2010 4:10 am

In my experience, 8-10VDC from 800m to 1.5A is fine across the board. The actual Twin adapter is an oddball 7.6VDC, and I've heard that this was due to the voltage requirements of its FDS circuitry, but that's unconfirmed.

You can use a standard (original connector) 9VDC Megadrive type PSU on it if you don't have an original Sharp adapter, or one from a Famicom SFC.