My first portable - any help appreciated!

[rig]

I am gonn a try and make a portable dreamcast. I read that some people say this is hard for a first project and some people said it wasn't. Guess I'll find out. Been reading up on how to do this and created a general checklist. Can somone add on or correct it for me please?

buy materials
hook up power supply, probably gonna use picopsu
hook up batteries (whats the difference between this and power supply?)
hook up screen
put a 7808 somewhere between power supply and PSone screen? I think?
hook up controller
make a case, i have a design in my head. just not sure how to actually make it.

When I get into the DC, how will I know what to solder where? Or is it very obvious?

thanks for any help

[cocoahoopz]

Hi there. I myself am getting into this whole DCp thing. All the pico psu does is take a DC input of 12V (I think) and dishes out the required voltages to run the Dreamcast (3.3V, 5V, and 12V). You need a total of 12V or so from your batteries to feed into the pico psu. The screen runs on 7.5V so you will have take 12V from the pico psu and run it through a 7808 (this will put out 8V but that is acceptable). You will see where the solder is. Just be careful not to destroy your circuit board. A multimeter is also very useful to check for continuity, voltage, resistance and all that fun stuff.

[hy phrend]

cocoahoopz is right. The Pico Psu takes 12v in and outputs the correct voltages where as the original PSU takes 120VAC. Read up in Family Guys DCP build/Pico Psu discovery thread and everything you need to know to get your Power supply working is in there. There are also a few variable input Pico PSU's that you can use. The ones you can use require 14-25 volts. If you go this route do not get the 6-26 volt variable input one as it does not supply enough current across the 12v line.

Most of the places you need to solder too are pretty obvious, although if you have any questions there are many pin-outs on the web so that you can figure it out if you need too. Also I hope that you are pretty good at soldering because unless you are lucky and open yours up and find that you have the revision 2 board (like I did and I believe cocoahoopz did) then your going to need to do quite a bit of soldering to relocate the GD-Rom controller board (50 pins so 100 solder joints). But it is definitely do-able. I have done it for a different project, took a little work but its not too bad. Just be sure to strip and tin all of the wires before you start. That way all you have to do when you go to solder the connections is put the wire down and heat up the solder. Takes tops 30 minutes to do all the connections if you strip and tin the wires first. Good luck and if you have any questions feel free to PM me or ask them in your thread and people will help out (be sure to do a lot of research about a question you have before asking it in your thread) Good Luck!

[rig]

I am a little confused. You say the picopsu takes 12v as input then gives out 3.3v, 5v, and 12v. Then you use the 12v given by the picopsu and put it through a 7808 to get 8v for the screen. If that is the case, why do you even need a picopsu? Can't I just connect 7808 directly to batterys that give 12v?

[hy phrend]

yeah you can do that. Just make sure if you do it that way that you put the 7808 after your power switch or else the screen will be on all the time. You need the Pico Psu though to power the dreamcast. Because it takes a voltage that can be given by a battery and converts it to the 12v, 5v, and 3.3v that you need to power the dreamcast. If you don't use the Pico Psu then some people have used a gamecube power supply but I think Pico Psu is easier to work with. You don't need a gamecube to take it out of. But you have to have some kind of power supply since you can't use the original one.

[rig]

Well, i already bought a picopsu-120 so ill go ahead and use it. Currently, I am shopping batteries and have some more questions I can't find answers to.

How much amps does the dreamcast+screen combo use? (searching this forum for 'amps' and 'amperes' gives no results ).

edit: Nevermind this question below, found answer is here http://electronics.howstuffworks.com/battery5.htm.
Does the mAh of batteries add together to give total mAh? For example, if I buy 10 AA batteries rated at 2500 mAh does this give me 2500 mAh or 25000 mAh? This -> http://forums.benheck.com/viewtopic.php ... =batteries suggests they do add up, but I think that is too good to be true.

another edit: After researching rechargeable batteries and shopping through a billion batteries I think I am going to use a cheap 12v 5A SLA battery from http://www.spytown.com/125ampba.html. I know it is huge, but I just can't afford to drop $100+ on the Ni-XX varietys and charger and I want it to last longer than an hour. To charge it I am probably gonna get this http://shopping.microbattery.com/s.nl;j ... =A&id=6267. This combo will only cost around $54 shipped. So, it won't be completely handheld. I will have a wire connect the battery to the handheld and just sit the battery in my lap or something. Not ideal, but itll do I think. I m not gonna buy them yet though, because I want to check with you that they will work for this. Will they?

[WERD]

Hey-this is Hy Phrend. I got a new name cause my other one was old. Anyhow...

I'm not sure exactly how much it draws. But from other peoples battery sizes and the time they get from their portable I would say it draws less than 2 amps but probably more than 1.5. With an LED modded screen you could probably achieve less than 1.5 amps.

That battery should work. Although I'm not too familiar with SLA and so I don't know what their fully charged voltage would be on a 12v SLA battery. The reason you have to be careful about that is because the 12v line on the particular model of Pico PSU you got, is unregulated, or in other words the power from your battery basically goes straight through to the Dreamcast. So if you give the Pico Psu 13+volts whatever is using the 12v output is actually going to get 13+volts. This only is a problem if the thing you are powering is really sensitive. I don't know if the Dreamcast is very sensitive or not so I can't help too much with the battery question. Hopefully someone with a little bit more knowledge on the SLAs can come lend a hand.

If that doesn't work out though a Li-ion 11.1v battery works like a charm.

[rig]

well i wasnt planning on doing the led mod, but if it can save me that much ma then i suppose ill do it if i can find cheaper led's than what the author of the book suggests -> http://search.digikey.com/scripts/DkSea ... D204UWC-ND

i am not paying $13 for 3 little led's. doesnt radioshack sell them?

[nevermind1534]

well i wasnt planning on doing the led mod, but if it can save me that much ma then i suppose ill do it if i can find cheaper led's than what the author of the book suggests -> http://search.digikey.com/scripts/DkSea ... D204UWC-ND

i am not paying $13 for 3 little led's. doesnt radioshack sell them?

I'll sell you three white 18000MCD LEDs for $5 shipped with resistors for 5V or 12V if you want them.

[WERD]

Yeah they do but I'm not sure if they sell just 3 LED's or what not. I did a search on Digikey and found some better deals with better specs then the one you linked to. Take a look at these, http://search.digikey.com/scripts/DkSea ... 60-1782-ND There are some for less than a dollar but I'm not sure on their quality. Digikey has weird shipping though so buying just 3 LEDs from them will not prove worth it as you will pay close to $4 for shipping. So unless you are planning on getting a lot of other stuff from them I would suggest looking somewhere else for LEDs. Just do a Google search for some LEDs. Also check ebay but if you go a route other than an electronics distributor then you will probably have to buy in bulk which isn't such a bad thing since you will have extras just in case and they can be used for other things.

nevermind has offered you a pretty good deal. I would go with that if i were you.

[rig]

Ok, I have pretty much all the materials except the stuff I need for LED mod. Nevermind1534 said he will send that in a couple weeks. Just finsihed a diagram so I know what I'm doing on the work bench.



It is just for powering on the DC and screen, not for video and audio. Does it look right? I have a few questions on things I don't understnad.

What do I do with all the grounds? I am lost here.
On the diagram in the area it says "will this work" I don't know how to get the 12v to the Dreamcast and to the 7808 so I drew a split wire. After thinking about it I don't know how I would split the wire and wonder how I can get the 12v from the PSU to the DC and 7808? Maybe use 2 wires? Also, how would the grounds work here?

[WERD]

All the grounds you just need to hook up to one of the G's on the Pico PSU diagram you have there. Ground is just 0v so your dreamcast ground and your screen ground can be hooked together and just connected to a Ground on the Pico Psu. The 7808 looks correct except make sure you ground that one as well. I believe it is the middle pin but don't quote me, look it up. And you simply just run 2 wires from the 12v out of the Pico Psu, one to the Dreamcast and one to the 7808.

[grayfox126]

I assume that shorting the ps_on and ground keeps the dreamcast on once power is connected to it, so for making a power switch, the switch should be placed between the PS_on and ground. Is this correct?

[WERD]

I think what shorting PS_ON to GND does is take the PSU out of Standby mode. But I'm not sure. Just Keep PS_ON shorted at all times and put the switch on one of the power lines from the battery. Positive or Negative doesn't matter. An easy way to short the PS_ON to GND I found was to take the chopped off lead of a resistor and place it from the PS_ON solder glob to the GND solder glob right next to it, heat up the solder and there you go, that way you don't have an annoying wire sticking out of your Pico PSU that can be knocked loose.

[rig]

First milestone reached. Got the DC to run off my battery.

At first I thought I fried my board because when I connected battery to the pico the dc light turned on but the drive wouldn't spin even when I would hold down that little black lever that tells it when the lid is down. Turns out my makeshift washer connections would jiggle around on the battery terminals causing the DC to act funny. To make the DC work like I wanted I had to make sure the connection didn't jiggle by slipping the washer on the terminal really fast. Gonna have to invest in some alligator clips. Here is a pic of when I did get it working good.



and here is a closeup of my crap soldering job on the DC board where the power comes in from the pico.



To short the PS_on to ground on the pico, I did something like WERD suggested. Except I didn't use any type of lead, just a bridge of solder.