Power supplies

[+johnnywc]

To all the techies:

 

I recently bought an Atari 4-switch on eBay and the power supply that came with it is not the stock Atari brand. It's rating is OUTPUT 12V 300mA. The regular Atari is 9V 500mA. My question is: Will the 12V hurt the system? I know the Atari steps down the voltage to 5V, but I'm not sure how it would handle the 12V coming in. Also, is 300mA enough current to drive the system?

 

Thanks,

[Ian Primus]

The Atari uses a 7805 voltage regulator to step down the power to 5 volts. The 7805 can handle up to 35 volts. The only thing that I would worry about is that since the amperage is only 300ma, in a worst case senario, you could concieveably burn out the power adapter. Another thing to think about is how the 7805 works. It steps down the voltage to 5 volts, and to get rid of that excess energy, it creates heat. Now the minimum input voltage for the 7805 is 7 volts. If you feed your 12 volts into it, it will still step it down to 5 volts, but the 7805 will heat up a bit more. If you were to feed it 35 volts, it would heat up a LOT.

 

What this means for you is this: your 12 volt adapter shouldn't hurt the Atari. Actually, if you put a voltmeter on an actual Atari supply these days, expect to get as much as 17 or 18 volts, as the parts in those things weren't exactly stellar, and have drifted over time. Another thing about the Atari is that it draws very little current, and 300ma should be sufficient, I have run it from a 9v 300ma supply for a long time and had no problems. (The Atari will even run for an hour or so off of a 9 volt radio battery!)

 

Ian Primus

[email protected]

[Skatepunk60]

300ma is kind of a stretch. The atari takes 500milli and its trying to rip 500 from a 300ma its gonna be hard. Point in case power supply will get very hot.

 

@Sark - i think they stopped w/ the regulator after the six switches? The power supply that came w/ my jr. ios right on , so is the one from my 4 switch

[Ian Primus]

The Atari power supply may put out 500ma, but that doesn't mean that the Atari actually uses it all. As for the power regulators, they have them in all the Atari's, and they are all the industry standard 7805. They are often relabeled with an Atari part number, but they are still the 7805. The power supplies that came with all versions of the 2600 were 9v 500ma, tip positive. What I was referring to in them drifting is this - the parts in them, most notably the transformer and capacitors, have a tendancy to drift in value with age, more so with heat and disuse. They still say 9v 500ma, obviously, but when they are connected to a multimeter set for DC volts, they are sometimes higher or lower than 9 volts. They don't always drift, but I've had a couple that did.

 

Ian Primus

[email protected]

[Skatepunk60]

Ohh i gotcha sorry dude im gonna go catch up on some sleep