Pics of my homemade TreamCast.

Nucklez · Post by **Nucklez** » Mon Jul 26, 2004 8:34 am

I'm not going to keep calling this a homemade TreamCast, but I knew you guys would know what I'm talking about. So far, this is what I've done. I've installed a 3rd party PSOne screen to the back on my DC. It is made by Interact.

http://www.nucklez.com/images/dreamcast ... ast001.JPG

1. In the above picture, you can see the screen in action. It isn't black and white like the picture looks, the cameras flash must've made it look like that. Notice the wire/switch sticking out of the DC where the modem goes, I have that temporarily rigged up for the GDRom lid open/close switch. The previous owner busted that switch all up!

http://www.nucklez.com/images/dreamcast ... ast009.JPG

2. This pic shows the back of the DC, with the screen attached. I removed the PSOne connector from inside of the screen so it would fit flush against the DC. I was also able to open up a hole in the bottom of the screen by removing a stand that allows the screen to stand on it's on. When I removed the stand, it freed up a hole just the right size to run the DCs standard AV cable through it. I cut a DC AV cable, and soildered the cable to the screen where I had removed the PSOne connector. Note: This was inside the screen, so no soilder is visible from the outside.

If you notice the long wire that plugs into the 7.5v jack in the back of the screen, I actually used the 12V car adapter that came with the screen, and I've got it connected to the 12V pin on the DC power supply. I'm going to shorten the cable the next time I have the DC apart.

http://www.nucklez.com/images/dreamcast ... ast012.JPG

3. This pic just shows the folded up screen. Isn't it cute.

Right now, I'm working on a circuit that will allow the DC to run off of a car cigarette lighter, and possibly a laptop 12V battery. I know this has been a nightmare, but I've got a circuit that will allow me 5 Amps total power within the 3.3V PSU pin. I've also gotten most of the transistors, and chips on hand. I'm waiting on a new breadboard that I've ordered so I can test the circuits before actually installing them. Wish me luck.

Disheveled DrFreeze · Mon Jul 26, 2004 12:48 pm

looks nice, i like that it doesnt look ghetto

i have a psone screen too, but seeing as i have a psone, i wont be hooking it up to my DC, it would be to much work

im am thinking of hooking up a laptop battery to that psone tough, problem is that those things are 12v, not 7,5

Arqueiro · Post by **Arqueiro** » Mon Jul 26, 2004 1:32 pm

nice work man !!! how this work ? just have a av intput ? what is the resolution ?

Nucklez · Post by **Nucklez** » Mon Jul 26, 2004 2:01 pm

It's NTSC for resolution. As for the AV, I removed the PSOne connector which was soildered to the screen via a ribbon cable. Then I wrote myself a schematic to determine which pin went to which part of an AV cable. Then I'm using the stock AV cable for the DC. I'm also thinking of adding a VGA adapter for the heck of it. I've also thought of painting it, but I kinda like the white. I'll keep updating this post as I update it.

As far as the screen is concerned. I got it off of Ebay for $30 US after shipping. Just be careful, as it needed a little work when I got it.

It does have and AV input for a DVD player or another system or whatever you wanna connect to it. The screen has a slot for AV Out too, but I have to get my hands on a PSOne AV cable. That won't be too hard at all. Local EBGames should have one.

Pyrosurfer · Post by **Pyrosurfer** » Mon Jul 26, 2004 3:38 pm

So how are you going to make the 12V in circuit (do you have a schematic?)?

Nucklez · Post by **Nucklez** » Mon Jul 26, 2004 3:51 pm

I remember you having the issues with yours on the 3.3v because it uses so much current. I have a 5 Amp 12V DC transformer that came off of some old electronic device. I'll get the model number for that if you need it. The circuit for the 3.3v is going to be the LM317 that you used, but I found a schematic that also has three LM395 power transistors in parallel to keep the current on them instead of the LM317. So it will take all of those chips to get it to work. It may not run near as hot, because the three LM395's are rated 1.5 Amps each, and with 3 in parallel the documentation says it will handle 5 Amps.

I'm still going to use a 7812 and 7805 for the other two leads on the PSU, because a car usually produces more than 12V. Hopefully I'll be able to connect the LM317 circuit to the full input, because it claims to be able to drop up to 35V down to 1.5V.

emptythought · Post by **emptythought** » Mon Jul 26, 2004 5:00 pm

Yeah man, that looks pretty smooth. Good work on it.

Pyrosurfer · Post by **Pyrosurfer** » Mon Jul 26, 2004 6:04 pm

It will have just as much heat output, but the heat will be spread out on each transistor. I suspect you might be able to get by if everything is heatsinked and you use a fan, but I would try switching regulators. The 7805 and 7812 should run fine though.

Warmachine · Post by **Warmachine** » Mon Jul 26, 2004 6:07 pm

Wow looking good. Good luck with it.

Nucklez · Post by **Nucklez** » Mon Jul 26, 2004 9:43 pm

Pyro, the schematic I've found will be using the three LM395 power transistors, and the LM317. The power transistors will keep most of the power off of the LM317 while it does it's job of dropping the voltage. It looks like it is going to be very efficient, but those LM395's are are around $3 US each. I'm trying to find a cheaper source, I don't want to spend a lot on this project.

As for the 12V input, I was a little mistaken, but hopefully this will still work. It's from an IBM ThinkPad, 16V DC with 3.36 Amps. That may not be strong enough to keep the DC happy. If not, I'm also familar with designing voltage rectifiers, which is mainly 4 high powered diodes. I've built my own power supply before that had a constant 12V simply using a voltage rectifier and a 10:1 stepdown transformer. Transformers are big, but it can always be placed in a "brick" between the DC and the wall.

Pyrosurfer · Post by **Pyrosurfer** » Mon Jul 26, 2004 11:31 pm

AFAIK, the design your using is still linear, so it will output just as much heat as mine did. The total heat output will be spread across the transistors. I think I recommended it before, but the gc power adapter would work perfect for ac->dc. Could you link me to the schematic?

Nucklez · Post by **Nucklez** » Tue Jul 27, 2004 8:18 am

Correct, the design is still linear, but the current will not all be focused on the LM317. I think most of your heat is because the LM317 is only rated 1 Amp, and your pulling 3.0 Amps or more through it. Your having to do one heck of a job heatsinking it, and I'm amazed that it hasn't cracked on you. The LM395's are high current power transistors, and are more suited for this job. I'm saying all this before I've actually built the circuit too, so I may be in for a big surprise when it's all said and done.

As for the schematic, I'll find the link and give it to you as soon as I can. I printed it up, and didn't bookmark it for some reason. If I have too, I'll scan it and post it for you.

Pyrosurfer · Post by **Pyrosurfer** » Tue Jul 27, 2004 11:39 am

So the design is linear, meaning the voltage is dropped by heat. You are trying to get 3.3V, so you have to drop 8.7V across the regulator assembly. You have 3A running though the entire circuit so you have about 10W dropped across the 3.3 dc section, and about 26 W in heat. It is going to run just as hot as mine. The LM317T is rated 1.5A not 1A. If it was rated 1A, and I used 2 in parallel, it would not work at all. The amperage rating is how much current it can handle if it is properly cooled, not how much heat it can produce. Use Switching regulators, Voltage is not dropped by heat with them.

dcmodder · Post by **dcmodder** » Tue Jul 27, 2004 1:16 pm

wow major props. great job. i'm thinkin about doin the same thing that you did Nucklez but i dont think i'd be able to afford the PSone screen.

spiroth10 · Post by **spiroth10** » Fri Jul 30, 2004 1:49 am

uhh for the car, why not get a converter from teh dollar store. they are like only a buck or two now. much easier. just plug it in.

I may make one... If I get the $$$$

Warmachine · Post by **Warmachine** » Fri Jul 30, 2004 1:57 am

spiroth10 wrote:uhh for the car, why not get a converter from teh dollar store. they are like only a buck or two now.

I thought they would be like $5.00 at the DOLLAR store

Nucklez · Post by **Nucklez** » Mon Sep 25, 2006 8:51 pm

Hey guys, I hate to bump this topic up, but I decided it would be good not to start a new topic. I decided to play with this project again after a couple of years. I wanted to fill everyone in on my progress. I'm kind of excited actually! I have been powering my DreamCast on a 12V laptop batter for over 1.5 hours. Just to note, this is running the PSOne screen that was in my old pics, and absolutly NO AC ADAPTER! I took some new pics because my circuit is currently on a breadboard. The setup is very "ghetto" at the moment, but I hope to make this work. The battery that I'm currently using is out of a PIII KDS laptop. It is rated at 5400 mAh, and has been running for 1.5 hours straight right now! I am also running the infamous 3.3v hella AMP circuit off of the battery as well. My current "secret" is three LM317's in parallel being heatsinked by a P4 CPU fan and heatsink. I think it is going to be overkill, but I'm keeping them installed for the test to see how long the battery will actually last.

I found a circuit to show how to put some 7812's in parallel and I modified it for the LM317's. Pretty much they were inline except for the Vout. Each Vout had a 2.2u cap to ground, then a diode. The ends of the diodes where connected to keep the voltage from the other LM317's from feeding the Vout of the other LM317's.

Next, I still had trouble getting the GD-ROM to spin up or the laser to operate off of the 3.3v circuit. What I found out was that the load of the DC was soooo heavy that even the Voltage Regulator couldn't keep up with it. After connecting the Voltage Regulator to the DC, I then adjusted the voltage to 3.3v. Without a load, the voltage is 4.8v.

Now for the hella heat problem. Even with three of these LM317's in parallel, it runs HELLA hot. I currently have a P4 CPU heatsink and fan connected to keep them cool.

Ok, it appears to be over. The battery has just died. 1 hour and 40 minutes, powering the Screen, the DC and the CPU fan. I tested it rigoursly for a while, running games that accessed the GD-ROM pretty hard, and then letting it run Sonic Adventure for about 45 minutes before it killed over. I'll get the pics up soon!

Post by **Christuserloeser** » Mon Sep 25, 2006 9:08 pm

Wow, that's some bump

Can't wait for the pics.

Nucklez · Post by **Nucklez** » Mon Sep 25, 2006 9:34 pm

Here are some pics!

Hopefully it is easy to tell that I'm not using an AC adapter, and it lasted 1 hour and 40 minutes on one battery. I don't have a recharge circuit yet, so I'm going to keep using the laptop to charge the battery for the time being. And yes, I suck at taking digital pictures.

Smurph · Post by **Smurph** » Tue Sep 26, 2006 7:06 pm

Nucklez wrote:Here are some pics!

Hopefully it is easy to tell that I'm not using an AC adapter, and it lasted 1 hour and 40 minutes on one battery. I don't have a recharge circuit yet, so I'm going to keep using the laptop to charge the battery for the time being. And yes, I suck at taking digital pictures.

Build your own PSU or mod the existing one to use 18V and you're golden.