12v PSOne screen power solution!!

segasonicfan · Post by **segasonicfan** » Thu Sep 08, 2005 1:35 am

I bought another Zenith PSOne screen and was opening it up when I came across a car adapter for it. It was rated 12v@ 3+amps. I found this very curious since the screen runs off 7.2v of course. Then I uncrewed the plastic clip that goes around the Gamcube and.....there's a full DC-DC converter circuit inside!! :O It uses the MC34063 to drop the voltage to 7.2v but retain the high current. This is a much better solution for my PSTwo portable than the 7808 I was using. Just thought you guys might like to know

-Segasonicfan

Foxx373 · Post by **Foxx373** » Thu Sep 08, 2005 2:44 am

I use the LM317 on my verge screen. It works up to 12V @ 1A.

segasonicfan · Post by **segasonicfan** » Thu Sep 08, 2005 3:47 am

Yea, that's basically the same as the 7808. From my understanding however, DC-DC converters are supposed to significantly decrease power usage but with identical results.

I just finished drawing up a schematic of the Zenith DC-DC converter design. The only thing that concerns me is the use of a NEC D882 NPN Transisor. It seems this transistor converts 5v to 7.55v which means it isn't all true dc-dc conversion but actually 12v-5v dc-dc and 5v-7.55v regulator. That transistor also gets DAMN hot. I wonder if it's worth implementing this converter in place of the 7808. Anyone think it's a good idea?

-Segasonicfan

Foxx373 · Post by **Foxx373** » Thu Sep 08, 2005 7:18 am

wouldnt it just be easier to go from 12v - 7.2v? What i did with my verge screen was use the LM317 to dull the voltage down to under 8.2V. After 8.2V my screen will invert the colors and contrast doesnt exist. I just use the LM317 to take a max of 12V down to about 7.8, then the internal regulators do their thing. I didnt make this an internal mod, this is purely external. I have the screen running from a 9.6V source, and its working just fine... When i run it from 12V the regulator gets a bit hot, so i just added a heatsink.

I did the same thing with my Intec 2.5" screen, except that one is internal.

segasonicfan · Post by **segasonicfan** » Thu Sep 08, 2005 12:25 pm

You don't understand what I'm saying. Theh 12v-7.5v conversion is all done at once, it just uses two small chips and some passives. Also, this is going to be internal and for a portable, that's why power usage is so important. 7808/LM317 is definitely the easiest method but I'm trying to increase the battery life of my PSTwo portable and I think this DC-DC converter will help.

-Segasonicfan

Foxx373 · Post by **Foxx373** » Thu Sep 08, 2005 1:31 pm

AHHH!! That clears things up a bit! I dont know anything about the Slim PS2 tough.