Sega Light Phaser to 7800 - Adventures in Fixing Old Crap (PIC HEAVY)

[Dopy25]

That's super sweet!

 

This whole thing got me thinking and I looked around for other methods and found this one:

 

http://www94.pair.com/jsoper/7800_gun_adap.html

 

I'm not too sure how a 7404 inverter would compare besides cost but it seems entirely possible to do with less parts. Do you have any experience with these kinds of inverters? The schematic linked shows only 4 pins used, and only 2 are data. Could a smaller inverter do the same thing? I wonder if this guy only had a 7404 on hand or if they were cheaper when it was written. 

 

I made an adapter with the same information you found, but not with the super cool board you made. For real dude. That's sick. 

 

I'm wondering about minimizing and using an inverter ic. Do you have any thoughts on that?

[+DrVenkman]

The transistor-resistor widget do the same as an inverter chip - they invert the trigger circuit to match what the Atari expects. They’re also cheap, certainly no more expensive than an inverter IC. There are only the 4 wires used for the light gun, which makes the adapter relatively simple. 

 

Anyway, my boards are done and should be here in 10 days or so.

[Dopy25]

Oh totally understand. It's a simple circuit for sure, and the 2 required components cost less than a single IC. I was able to get it working and fit the components into a db9 shell with an adapter for sega controllers as well. I was just wondering about the possibility of using a single component to minimize space usage inside the shell. It would also make for the possibility to redraw the board used for the sega-atari conversion and add an surface mount inverter to the mix and potentially have a single in and out for the whole thing. Right now I feel like my adapter looks janky, but it does work. I just have to have a switch to go between the controller and light phaser inputs.

 

I didn't mean to diminish what you did. I seriously love your board. I've never made one in my life but I like to modify stuffs. 

[leech]

On 5/16/2021 at 7:17 PM, DrVenkman said:

I ended up using EasyEDA. Not sure it’s any easier but it works pretty well.  Hopefully the connector footprints are accurate! I’ll know in about two weeks. 

It's funny that I see this post today, I was legit thinking last night of trying to figure out how to design a board to replace the one inside the standard 7800 controller with one that has microswitches. 

 

I have an XG-1 light gun, need to think of how to hook my 7800 to a CRT somewhere and try it out, but I have the Sinden Light gun on the way (at some point) and I think there really needs to be a USB to DB9 adapter for such a thing...

[leech]

5 hours ago, DrVenkman said:

The transistor-resistor widget do the same as an inverter chip - they invert the trigger circuit to match what the Atari expects. They’re also cheap, certainly no more expensive than an inverter IC. There are only the 4 wires used for the light gun, which makes the adapter relatively simple. 

 

Anyway, my boards are done and should be here in 10 days or so.

Hmm, I should build one (just for fun, as I don't own a Sega Light gun (or maybe I should pick one up!)) and then use TinkerCAD to design a case for it.

[Dopy25]

46 minutes ago, leech said:

It's funny that I see this post today, I was legit thinking last night of trying to figure out how to design a board to replace the one inside the standard 7800 controller with one that has microswitches. 

 

I have an XG-1 light gun, need to think of how to hook my 7800 to a CRT somewhere and try it out, but I have the Sinden Light gun on the way (at some point) and I think there really needs to be a USB to DB9 adapter for such a thing...

Not sure about db9, but it looks like they are using a Pi to communicate with Ps1 & Ps2. The PS2 has usb but I know the PS1 does not so I have no idea how they are implementing that but I am sure the output on the pi can be converted to the necessary data lines for Atari if it can be done for PS1. I guess you'd just need to use a pi as a converter.

Edited May 19, 2021 by Dopy25

[leech]

36 minutes ago, Dopy25 said:

Not sure about db9, but it looks like they are using a Pi to communicate with Ps1 & Ps2. The PS2 has usb but I know the PS1 does not so I have no idea how they are implementing that but I am sure the output on the pi can be converted to the necessary data lines for Atari if it can be done for PS1. I guess you'd just need to use a pi as a converter.

Would be awesome to be able to get a better light gun for older systems that would work on an LCD! 

[+DrVenkman]

On 5/19/2021 at 6:53 AM, DrVenkman said:

Anyway, my boards are done and should be here in 10 days or so.

So my boards left China this morning, and the male and female DE9 connectors I ordered from Digi-Key on Sunday arrived yesterday. So hopefully next week I will be able to build my little adapter and be sure I got it right.

 

If everything's okay, I'll make a couple little layout tweaks I should have thought of the first time that will make things easier if someone wants to 3D print a shell or something. Then I'll order another run of samples to verify the tweaks are right. After that, I'll post the Gerbers for anyone who may want to build one themselves in the future.

[+DrVenkman]

My boards arrived in Memphis this afternoon, just a few hours away. So with any luck, I'll have them in another couple days and I'll be able to verify I didn't screw up such a simple layout, lol. And not a moment too soon - I went to play ALIEN BRIGADE tonight only to find I'd snagged my contraption in the last couple days and pulled one of the wires free from the terminal block connectors I'm using. D'oh!
 

Fortunately that was a quick fix.  Soon I was blasting the ever-loving frak out of green a-holes again. I managed to clear the first stage and get through most of the second before I died. The game is SO much more fun with a light gun than a control pad or joystick.

[+DrVenkman]

So … yeah. I’ll be making at least one major change for the next revision. ??? #Doh

 

 

I have no idea how I missed this before I submitted the design. Live and learn. At least they were cheap.  

[+Karl G]

So, for those of us less electronically inclined, what was the issue?

 

Edit: the port is facing the wrong way, right? 

[Dopy25]

Solder from the underneath?

 

Also, on the plus side: THEY FIT! Good job, doc!

Edited May 24, 2021 by Dopy25

[+DrVenkman]

35 minutes ago, Dopy25 said:

Solder from the underneath?

That will swap pin assignments left to right. But all in all, not a huge deal. As I said, they were cheap. I’ll revise and order new boards with the wayward connector swapped around 180 degrees.  

[Dopy25]

1 hour ago, DrVenkman said:

That will swap pin assignments left to right. But all in all, not a huge deal. As I said, they were cheap. I’ll revise and order new boards with the wayward connector swapped around 180 degrees.  

Haha I guess you're right. But as a scientist, trial and error, am I right? Good job for a first go!

[Bratwurst]

Those boards are still salvageable, just solder in a corded 9-pin connector- you'd want that extended away from the PCB anyway, as they're much easier to plug into the system.

[+DrVenkman]

9 hours ago, Bratwurst said:

Those boards are still salvageable, just solder in a corded 9-pin connector- you'd want that extended away from the PCB anyway, as they're much easier to plug into the system.

Yea but then I have to cut off a cord, tone-out the pins to each conductor, solder them all in, etc. The whole point is to make this a simple plug-in board. So I’ll revise and get new boards made. As I keep saying, these were cheap.  

[Tempest]

13 hours ago, Karl G said:

So, for those of us less electronically inclined, what was the issue?

 

Edit: the port is facing the wrong way, right? 

I'll admit that it took me waaaay too long to see that.

[+DrVenkman]

42 minutes ago, Tempest said:

I'll admit that it took me waaaay too long to see that.

Yeah, me too! ?

 

As a practical matter, EasyEDA lets you do a 3D render of the board right within the program itself. But these DE9 connectors aren’t available in the model library so far as I could find. I like to believe that had they had the connectors in their model library, I’d have seen the problem before I submitted the design. Oh well. I will view this as a rite of passage and fix it. 

[Tempest]

So is the SMS light gun actually more accurate than the XE gun or is that just an urban legend?  I always thought the accuracy was due to the code itself, not the actual gun being used.

[gilsaluki]

1 hour ago, Tempest said:

So is the SMS light gun actually more accurate than the XE gun or is that just an urban legend?  I always thought the accuracy was due to the code itself, not the actual gun being used.

Totally urban legend.  Total hype. The SMS light Phaser, the Best Light Gun, Atari's Light Gun are all equal.  I have them all.  Given that most people only use them within a foot or closer to the screen, they all have their inaccuracies. While one will hit slightly to the upper left, some do the opposite.  I really have not seen any advantage of one over the other.  I play a lot of light gun games, Barnyard Blaster is probably my favorite (I know a lot of people pan it).  Once I figure out the offset, I can nail those little varmints (and cans & bottles).   I too believe it's in the software coding. 

[+DrVenkman]

Got no clue myself. I did notice when I took mine apart to diagnose/repair, the inner surfaces had some dust and light grime - possibly a bit of decades old nicotine residue. I cleaned the photodiode as well as the plastic magnifier lens just to be sure. I’m playing on a 27” CRT from about 4-5’ away and haven’t noticed any real accuracy problems. Probably comes down to the game code. 

[+DrVenkman]

Board revised. Connector orientation for that pesky female DE9 corrected. Boards ordered. I should have them next early next week.

 

[john_q_atari]

On 5/24/2021 at 3:58 PM, DrVenkman said:

So … yeah. I’ll be making at least one major change for the next revision. ??? #Doh

 

 

I have no idea how I missed this before I submitted the design. Live and learn. At least they were cheap.  

I laughed when I saw that. You should make that your avatar. Totally awesome.

?

[+DrVenkman]

2 minutes ago, john_q_atari said:

I laughed when I saw that. You should make that your avatar. Totally awesome.

?

I couldn't help but laugh myself when I discovered the screwup. I showed it to my wife and she immediately deadpanned, "Huh.  Looks like you need an adapter for your adapter." ?

 

So yeah. I own up to my goofs and share them for a couple reasons. One, to show everyone who may want to try something new (like PCB layout!) that it's okay to try and then screw up. And two, it's not that big a deal when you do and most mistakes can be fixed pretty easily. 

 

Plus it was just damned funny.

[+DrVenkman]

Got the new boards today - 7 days from the day I ordered (last Wednesday evening) until delivery early this afternoon. Looks like I got it right this time!

 

I am toying with doing a third revision to shrink the length and width of the board for convenience, and also to very slightly widen the footprint spacing of the transistor pins. I used the default footprint in EasyEDA and although it lets the transistor sit flat on the board nice and neat, the pads are ridiculously easy to bridge when soldering the legs. You DO have to remove the mounting screw posts on the female (Atari) side DE9 connector, as then interfere with plugging into the 7800 directly (yes it fits, barely!) or using a joystick extension cable. But the bare plastic shell fits the Atari joystick connector and a standard 9-pin joystick extension cable very well without it, without being loose or easy to dislodge.