7800 controller mod

[captainrhythm]

I am looking in to options for modifying controllers to better play Robotron: 2084 with.

 

As of right now I'm at a stand still for two reasons:

1.) I can't find any digital thumb-stick options

2.) I can't find any way or any helpful information on how to convert an analog controller's potentiometer to act in a digital on/off fashion. (My own experiments in this area have failed)

 

A digital thumb-stick seems to have never been produced so I've largely ruled it out, but I'm still holding out hope I can figure out a way to convert the analog's potentiometer--what better set up than a dual shock for Robotron, right?

 

Any ideas?

[SRGilbert]

Found this on the google

 

http://www.e-clec-te...m/joystick.html

 

 

Or maybe you could canablize the hat switches found on many pc flightstick type of joysticks. I see those at thrift stores all the time super cheap.

Edited March 3, 2010 by SRGilbert

[BigO]

I am looking in to options for modifying controllers to better play Robotron: 2084 with.

 

As of right now I'm at a stand still for two reasons:

1.) I can't find any digital thumb-stick options

2.) I can't find any way or any helpful information on how to convert an analog controller's potentiometer to act in a digital on/off fashion. (My own experiments in this area have failed)

 

A digital thumb-stick seems to have never been produced so I've largely ruled it out, but I'm still holding out hope I can figure out a way to convert the analog's potentiometer--what better set up than a dual shock for Robotron, right?

 

Any ideas?

 

I'm not really familiar with the requirements of controlling Robotron 2084. What are the shortcomings of traditional controllers?

 

Ideas? On item 2: Op amps (comparators) might do the job. A microcontroller (PIC for example) with an analog to digital converter built in could probably do the job with relatively little coding. Actual implementation would depend on the particulars of the analog controller you're trying to use.

Edited March 3, 2010 by BigO

[captainrhythm]

I'm not really familiar with the requirements of controlling Robotron 2084. What are the shortcomings of traditional controllers?

 

Ideas? On item 2: Op amps (comparators) might do the job. A microcontroller (PIC for example) with an analog to digital converter built in could probably do the job with relatively little coding. Actual implementation would depend on the particulars of the analog controller you're trying to use.

 

Well, to play it properly you need to use two controllers--one to walk around, one to fire--and with 7800 or 2600 controllers it's a little imprecise and uncomfortable. What I was aiming at was having a single controller with dual sticks and two cords. As for the technical electronics stuff... I have no idea. From what I've read, that sounds like a solution that's be proposed before, but it's simply too much for me to put together at the moment. I think I might just replace the resistance material inside the potentiometer with some copper or aluminum with some space in the center and go from there, I was just hopping I didn't have to.

[BigO]

A thought occurs to me...

 

When the wiper (connected to the center tap) of a typical potentiometer is rotated the full distance one way or the other, it makes a near zero resistance connection with whichever end the wiper is rotated to.

 

The problem you have is that you don't want all that analog-y crap happening between those extremes.

 

If you have an ohmmeter, you might try measuring the resistance across the potentiometer when the controller is actuated to one extreme. If you can get zero at both extremes, there might be hope.

 

To turn it into a "digital" device, dismantle the tiny little pots and sand off the conductive/resistive material except for at the very ends of the travel. Then you'd have the center common and open circuit on both the other pins until you rotated the pot to that extreme. I say "sand" as opposed to gouging it off with a hammer and chisel because the wiper would still need to slide across the surface.

 

After the pots are modified, you'd have to rewire everything to get rid of the active electronics and make it all act like 7800 controllers including the buttons.

 

I know I'm being pretty vague and rambling, but it might be possible. The key will be determining if the minimum resistance available through the pot at the opposite ends will work to trigger the console. I don't believe the resistance would have to be completely down to zero.

 

Expecting there to be very little current flow through these I/O lines, it may well be that a 5k ohm resistance would still allow the signal to be recognized properly by the console. 5K is significant because almost all of the thumsticks I've seen use 10K ohm pots. Sanding out just the center portion of the conductive path would allow the sticks to act digital without having to push them to the extremeties of their physical travel.

Edited March 4, 2010 by BigO

[Almost Rice]

If you have the space, dual joysticks on a arcade panel is the way to go. I always wanted a dual thumbstick option to play robotron. Let me know if there is a produced unit that is easy enough to modify for the 7800.

[SRGilbert]

Well you could mod an X-arcade stick easy enough, but that might be overkill.

[captainrhythm]

A thought occurs to me...

 

When the wiper (connected to the center tap) of a typical potentiometer is rotated the full distance one way or the other, it makes a near zero resistance connection with whichever end the wiper is rotated to.

 

The problem you have is that you don't want all that analog-y crap happening between those extremes.

 

If you have an ohmmeter, you might try measuring the resistance across the potentiometer when the controller is actuated to one extreme. If you can get zero at both extremes, there might be hope.

 

To turn it into a "digital" device, dismantle the tiny little pots and sand off the conductive/resistive material except for at the very ends of the travel. Then you'd have the center common and open circuit on both the other pins until you rotated the pot to that extreme. I say "sand" as opposed to gouging it off with a hammer and chisel because the wiper would still need to slide across the surface.

 

After the pots are modified, you'd have to rewire everything to get rid of the active electronics and make it all act like 7800 controllers including the buttons.

 

I know I'm being pretty vague and rambling, but it might be possible. The key will be determining if the minimum resistance available through the pot at the opposite ends will work to trigger the console. I don't believe the resistance would have to be completely down to zero.

 

Expecting there to be very little current flow through these I/O lines, it may well be that a 5k ohm resistance would still allow the signal to be recognized properly by the console. 5K is significant because almost all of the thumsticks I've seen use 10K ohm pots. Sanding out just the center portion of the conductive path would allow the sticks to act digital without having to push them to the extremeties of their physical travel.

 

The problem here is that the analog stick housing, controller housing, and the plastic sticks themselves actually limit the rotor movement a LOT.

 

ex:

 

So that the resistance never really gets a chance to go beyond the very center range. Also, I experimented with a desoldered analog stick housing--connecting the center line (W in diagram) to pin 1 and one of the sides (A, B in diagram) to pin 8--and no matter the position, the Atari simply did not pick up on ANY current from a completed circuit which means I would have to have an interpreter of some kind which is far from my skills in electronics.

 

So, I've opted for the method I mentioned before: a replaced resistance board inside the potentiometer housing (copper, etc.) with a gap for the centered analog stick.

 

ex:

 

For example, I'd attach (A) to pin one, (W) to pin 8, and (B) to pin 2, making this one potentiometer a digital up/down controller.

 

Thanks for the thoughts though, I'm just not very educated in electronic engineering--I'm just a tinkerer--and while this project is rather dear to me, it's simply not worth the effort of learning a large, completely new skill set to achieve success. After all, there's MAME and PC analog controllers, and a 360 live arcade version of Robotron... making it a little moot.

 

If you have the space, dual joysticks on a arcade panel is the way to go. I always wanted a dual thumbstick option to play robotron. Let me know if there is a produced unit that is easy enough to modify for the 7800.

And

Well you could mod an X-arcade stick easy enough, but that might be overkill.

 

The arcade stick thing, I thought of that first... but, if I wanted to go that way, I could have just built a housing like the ones offered in the first place for Robotron--you know, the plastic thing that held two controllers. So, that was kind of the 'easy way out'... on both accounts.

 

Thanks all for letting me kick some ideas around. I'll post later (probably much later) on how successful I am with this current plan.

[BigO]

No matter what position the wiper was in you could never get it to activate the 7800? Not even with it cranked to near zero? That surprises me. Do you know what the resistance was at that point?

 

Mechanically speaking, I expect some challenges trying to get the wiper to step up onto the added foil/copper without catching the edge (possibly damaging the mechanism over time). Something to fill the gap smooth the transition might be necessary; some hard curing epoxy like JB weld maybe? Do keep us informed on your progress. I for one am always interested in these sorts of projects.

 

I have a project planned for "someday" that will in part use a microcontroller to make an analog controller compatible with a digital system like the 2600/7800, etc. but your way is potentially much more accessible to normal people.