Need advice for PCB

[Viso]

I'm designing a board for a new gizmo -- a memory module for the 2600 and 7800 (see http://home.hiwaay.net/~jeffj1/projects/amm/index.html). I haven't before made a board that I intended to put into some enclosure to make it a pretty gizmo in a box, so I'd like some advice.

 

The gizmo has 3 DB-9 connectors, a cable to connect to the game console, and maybe a power connection. I was figuring I'd use PCB mounted right angle DB-9's. Is this a good idea, or would it be better to have a ribbon cable connected to the board? I've also been positioning the DB-9's to hang off the edge of the board a little -- good or bad?

 

Right now, I've managed to fit it on a 3x5 inch board. I can put it on smaller boards, but I haven't been able to fit all 3 DB-9's on anything smaller in an enclosure that I know about. Also, I'm not using any surface mount components because I lack the soldering skill to work with those. Should I go for surface mount? Are there any good enclosures I should consider?

 

I've got the gizmo set up with a controller pass-through port. The first 4 pins of the controller pass-through port are put through a 4016. I did this so that the module could disconnect the pass-through port to prevent joystick motion from interferring with memory module communication. I haven't done any stress testing on this. Can a 4016 handle the current going through an Atari joystick?

 

If a 7805 is always connected to the +5v power line but isn't always supplying the power -- the +5v could be there while the Vin pin is left floating -- will the 7805 be damaged?

 

Thanks for any advice, and have fun!

[Kroko]

Hi,

 

here is a picture of two of my PCBs with different

connector types. They both work, so its a question of

space and taste.

 

Kroko.

[Tsukasa]

I would find an enclosure that you like, and then size the board and connectors to fit.

[Tsukasa]

Also, no the 7805 won't be damaged. I wouldn't suggest trying surface mount, there are special soldering stations that are necessary to solder them to the board, these are generally very expensive.

About the joystick current, the 4016 should be fine.

[Viso]

Thanks for the input; I have a much better idea of how to proceed now. I picked up what seems to be the Serpac 131 enclosure so I can get a better feel for its shape. I was planning to use the Serpac 032, but I think the board shape and layout will be identical.

 

I'm going to fit the 7805 and a common power connector (needed to power the gizmo while connected to a serial port). I realized I can make the board a bit larger, so I think it won't be a problem. While I'm at it, I'll try to get the placement of the DB-9 connectors right.

[Viso]

Now that I'm getting fairly close to having what looks like a good layout, I'm going to need to send that layout to someone who can make a nice 2 layer PCB. I've made single layer boards, but 2 layers is a bit beyond what I can personally do.

 

Who will make a board inexpensively for me? So far, it looks like http://www.pcbfabexpress.com is the best choice.

 

Thanks for the help!

[Tsukasa]

Stop!!!!

 

Go to future electronics instead.

They offer boards for much cheaper....

[Tsukasa]

Oops! I posted the wrong link! Here's the correct one. www.futurlec.com

[+5-11under]

Oops! I posted the wrong link! Here's the correct one. www.futurlec.com

 

That looks like an awesome deal for low quantities.

5-11under

[Viso]

Stop!!!!

 

Go to future electronics instead.

They offer boards for much cheaper....

Thanks Tsukasa! They're not really cheaper per board, but I don't need 4 or 5 to test with. The lower minumum should cut the total cost in half.

[snafles]

Its hard to beat www.barebonespcb.com for quick and dirty prototype boards. The problem I have is that no mask sucks for surface mount.

[Tsukasa]

I don't use surface mount cuz I don't have the right tools....

[tangent]

would it be better to have a ribbon cable connected to the board?

A ribbon cable will add to the cost, but it'll give you some mounting flexibility.

 

If you're not going to have the case professionally punched or milled, you should probably go with board-mount connectors since you don't need to rely on precise cutouts so the connectors mount securely. You just screw to board to the chassis and then you can use ugly rectangular cutouts.

 

I've also been positioning the DB-9's to hang off the edge of the board a little -- good or bad?

As long as you're fully supporting the connector, it shouldn't matter either way.

 

I'm not using any surface mount components because I lack the soldering skill to work with those.

SOIC size chips aren't all that hard to manage. Soldering isn't tricky, it's desoldering that will kill you. That's what the special tools are for. If you only have a few parts, it won't be too hard to get it right the first time.

 

Passives are even easier, since there are only two legs. 1206 parts are pretty easy.

 

In the middle are things like SOT-23 transistors.

 

The really difficult ones are the high pin count chips, especially with pin pitches narrower than 0.05".

 

All that having been said, I still do everything thru-hole when I can get away with it.

[snafles]

Just found www.pcb4u.com. They will do a 2 layer with mask and silkscreen, 20sqin for $10 a board, you must buy 5 of them though. No setup charge. Go to the 5 piece deal on the front page. This is the best deal I have ever seen, its a little more than 1 barebonespbc boards, but you get 5 of them and mask and silkcreen.