Polarity Switch Adapter/Cable for 5.5mm X 2.1mm AC Adapters

Considering Genesis and Famicom original adapters are overpriced and will tend to be faulty due to their age, I've been looking for an alternate way to power the systems through the 5.5mm by 2.1mm jack.
I've been looking at the Adafruit AC adapter and this thing. Both are UL tested, as opposed to the cheap ones on eBay. However, they are generally center positive, when the official adapters are center negative. I'm looking for one of them polarity switch cables, but unable to find the exact terminology to find the product on eBay or Amazon. Can anybody help? Thanks.

 

They are DC not AC.
I just made a high current supply to run all my 9v systems and just switched polarity in the plug...
If you are really worried about accidentally reversing the polarity, you could mod the systems with a Bridge rectifier inline between the female barrel jack and PCB.
My PAL SNES will run fine on a DC PSU as it goes directly into a Bridge rectifier but if I plugged my SNES's AC PSU into my MegaDrive, it may damage something.
here is my psu I built.

 

What I do is open up the ac adapter and switch the polarity.

 

Switching PSU. Yuck. Don't do it! Dirty power.

Absolute rubbish. Mine are all fine. We had hundreds come through the shop and the vast majority were all fine.

 

A lot of consoles use switch mode power supplies, a lot of high end equipment does too

 

Here is one:
http://console5.com/store/dc-power-...andard-power-supply-to-6-different-plugs.html

 

There are reasons why they do it - including cost. It doesn't stop the fact that it gives dirty power. PFC in PC PSUs helps somewhat, but I doubt there's much in these for the price.

 

Oops, yeah, I've ONLY been looking at AC to DC adapters, as the original units had them. I know that make the polarity switching cables but I can't seem to find them properly. I might as well just get the extensions with the wires exposed and solder them into a blank jack.
I don't really want to crack open the actual adapter, only to have to tape the casing back together.

 

mickcris linked you to one. Those ends are reversible.

A decent adapter will have screws.