Need Paddle Control

[jgsing]

For a series of Interactive Museum Exhibits I am building I need a traditional paddle control.  This is similar to what was in Pong or Breakout. That is a potentiometer based control that turns less than a full circle and returns to the 12:00 position when released.

Anyone know where I can find something like this?

Thanks,
John

[RandyT]

This would be a pretty specialized control.  Your best bet would be to hack a flight stick with a twist "rudder" control.

RandyT

[paigeoliver]

The Pong and Breakout controllers do not return to center. I have owned a half dozen Pong clones over the years (still have one) and I played the Breakout machine at John Yates' arcade museum a few months ago and none of those return to center. They turn about 270 degrees before stopping, but many styles use a slip-grip mechanism that will let them turn past the stops (to no effect of course).

A standard atari 2600 paddle is cheap and easy to find and would work. If you want the heavy duty arcade style then register for the forums at arcade-museum.com and post a wanted to buy posting and say you want a pong type controller, clones ok.

[paigeoliver]

You may also just want to buy a cheaper Pong clone like this.

http://www.ebay.com/itm/Vintage-Cocktail-Table-Video-Arcade-Pong-Coin-Operated-/330789073526?pt=LH_DefaultDomain_0&hash=item4d0490b276

Pull a paddle, use it while you need it and then put it back and resell the whole machine when you are done.

[RandyT]

I think you may have misunderstood the request.  He's looking for a potentiometer based control, like a Pong controller, but one which returns to center.  Not specifically a Pong controller.  The only place I have seen anything remotely similar is the rudder control on a flight stick, where one can twist the stick and it has a spring loaded return to center.

[paigeoliver]

I had actually assumed he misunderstood his own request and had attributed a false property to the controller he was looking for.  Honestly it is rather hard to come up with an idea where a return to center knob is an ideal control (40 years of arcade games never produced one).

The rudder on a flight stick has little movement, just a few degrees left and right. If return to center is truly the important part of the controller equation then a knob is not the ideal choice. Something similar to the Surf Planet controller would be more appropriate.

I think you may have misunderstood the request.  He's looking for a potentiometer based control, like a Pong controller, but one which returns to center.  Not specifically a Pong controller.  The only place I have seen anything remotely similar is the rudder control on a flight stick, where one can twist the stick and it has a spring loaded return to center.

[SavannahLion]

There are several ways to tackle the problem depending on how much space you have inside vs how small you want to thing to be. If you have the $$$ you can find RTC pots. The first place I looked in my own quest was with RC paddle controllers. But I found two different types, the el-cheapo models where the controller itself was the RTC mechanism. Bleh. The second type was the kind with actual self contained RTC pots. but these were absurdly expensive to buy by themselves. It would've been cheaper just to buy a high-ish end controller and yank the pot from that. I looked elsewhere but it was generally the same. RTC pots are pricey. So I started building my own (I ended up not using pots so it was all moot but I still have the design sketches).

I don't know how much space you have to work with but you can try something along these lines.

In a nutshell, you're going to take your pot and slip on a horn, arm, hub or some variation. They'll look something like the type used for servos but sized for your chosen pot. They're reasonably easy to make, kind of a PITA to permanently attach to the shaft though. But I digress. Slip your horn over the shaft then install into your panel as appropriate with the nuts. The next part takes a bit of experimentation. You'll need to find a spring or two with just the right tension so that there is enough slack for the spring to "give" when it goes against, but with enough spring that it will pull against the arm in the opposite direction. You'll also need to anchor the springs somewhere inside the box.

That's the basic mechanism. I've seen several variations on this. I think X's version used a wooden dowel and a single eyelet and spring to get RTC behavior. Another version used a piece of string tensioned between two springs and two tensioners. Very nice. Then complexity easily ramps up from there, involving gears, chains, or whatever. But the basic principle is always the same.

Note: it will be very difficult to get much more than 180 degrees (or thereabouts) with just a basic method of using the arm. You'll need to resort to a gear or chain system and leverage useful ratios to get beyond this limitation. It wasn't an issue with my own project so I never looked beyond this.

It's doable.

Good luck

[Lilwolf]

Since it turns LESS then a full circle, I think you could use a omega race type controller.  Trouble is, that one seemed a bit less stable then others.

[jgsing]

Wow!
You guys are awesome.
I think one of these suggestions will do the trick for me.
Randy, Paige, SavanahLion and Lilwolf, I really appreciate all of your kind help.

John

[PL1]

jgsing - How many degrees of turn are you going for?

When I think of a spring loaded potentiometer, I think about the Star Wars yoke.  The x-axis turns a little over 90 degrees (45 degrees left and right) and the y-axis turns around 45 degrees.  The spring mechanism is visible on pages 51 and 52 of the manual here.

If you need more degrees of turn, you might want to adapt a mechanism similar to the one in this build.

I'm thinking about two springs like this.



Scott

[Vigo]

To be honest, your standard cheapo PC racing wheel is just a pot that returns to center. Generally they turn less than a full circle as well.

I would say either modify a $20 racing wheel with to have a dial or whatever you need, or replicate the principles used in a racing wheel to make your pot return to center.

The way the standard racing wheel makes it return to center (as i have seen) is just a bungee cord through the shaft of the wheel, and a hunk of plastic holding the bungee in place. you turn the wheel, it stretches the bungee cord and makes it bounce back to center when you let go.

[RandyT]

The cheap PC steering wheel is a good thought.  But anything other than a setup using a very high quality pot, probably isn't going to last very long in a public setting. 

A DIY solution with a tried and tested long life potentiometer will probably be the ultimate solution here.  The earlier mentioned single eyelet (screw eye extending from the shaft, etc.) with a properly selected spring or heavy-duty rubber band, seems like a great approach.

[SavannahLion]

To be honest, your standard cheapo PC racing wheel is just a pot that returns to center. Generally they turn less than a full circle as well.

Yeah, those were some of the first ones I looked at. Every brand I looked at at the hobby store in the el-cheapo price range weren't true pots or, if they used pots, weren't true independent RTC pots. The shell of the controller is what housed the RTC mechanism, not making it worthwhile to disassemble since one would put in the same amount of work to make one from scratch. The true RTC pots I found started with the $60ish and up controllers. I suppose I could've ordered some online but I had no interest it buying a dozen cheap controller just to find out.

jgsing - How many degrees of turn are you going for?

When I think of a spring loaded potentiometer, I think about the Star Wars yoke.  The x-axis turns a little over 90 degrees (45 degrees left and right) and the y-axis turns around 45 degrees.  The spring mechanism is visible on pages 51 and 52 of the manual here.

If you need more degrees of turn, you might want to adapt a mechanism similar to the one in this build.

I'm thinking about two springs like this.



Scott

Yeah, that's the design I was thinking about, though I think X just used one spring? I can't recall but his name is mentioned on that link you provided.

To the OP, there is some additional improvements to that design if you go with it if you want something long term and ease of repair.

[RandyT]

Yeah, that's the design I was thinking about, though I think X just used one spring?

Something else the OP may want to consider:

1 spring approach:  Very easy to implement.  Center will always be pretty reliable.  The disadvantage will be that the further the knob is turned, the more resistance there will be.

2 spring approach:  More parts.  Center will require some tweaking and may move when the springs start to wear.  A means of tweaking the center point might be a good idea for maintenance.  The main advantage is that, depending on how the springs are arranged, a more even resistance is possible.

[PL1]

Along the lines of spring arrangement, this is a modification of the other design. (Not drawn to scale.)

The springs wrap around the yellow shaft, requiring less stretch percentagewise.

The gray and purple form a mechanical stop that allows just shy of one full turn.


Scott

EDIT: Edited the diagram to correct the spring placement in the end view.

[SavannahLion]

2 spring approach:  More parts.  Center will require some tweaking and may move when the springs start to wear.  A means of tweaking the center point might be a good idea for maintenance.  The main advantage is that, depending on how the springs are arranged, a more even resistance is possible.

Yeah, small cable tensioner might fit the bill. Or a length of cable drawn through a pair of nuts for each spring will do the trick. Though one could pre-tension a nice stiff spring in a similar arrangement as PL1 suggests will ensure a nice long life. This is exactly how some gate springs are set up.

[PL1]

Even small turnbuckles are too big for this project.

You could move the eye bolt to the end and use a nut to adjust the tension like below or you could use the original design and increase the tension by using a loop of mechanic's wire (also called safety wire) shaped like this that you can tighten by turning the twisted end to make the loop smaller.




Scott

P.S. Edited the earlier diagram to correct the spring placement in the end view.