notes on my electrically rotating monitor

[danny_galaga]

silver posed a few questionrecently and i thought i might as well share my notes. cut and paste notes on software implementation:

anything that is NOT software related i can get my head around (",). so for instance, if you replaced the toggle switch with two power transistors you should be able to have the monitor rotate with nothing more than two different constant signals. each signal is like flipping the toggle. thus nothing complicated to work out signal-wise. two different signals from the parallel port for two different transistors. thats it! the signal can stay on since the microswitches 'tell' the monitor when to stop. roughly speaking-

[danny_galaga]

obviously you'll need to save the pics to read the text!

[Silver]

Good job - thanks for sending me the info.

I'm looking into settup up a bistable circuit to achieve the same thing if a keypress(IPAC).

And on controlling-from-software-via-parallel-port issue (in XP anyway) I'm sure the problems could be got around by having a master switch to be hit after boot up - or s timer delay circuit to stop rotation in the first minute during boot or something...

[danny_galaga]

just think how impressive it will be when it automatically rotates on game selection, silver

ok, some pics of my set up. first pic is 15" pc monitor on its turntable. wheels are ball-races.

second pic is the microswitch arrangement. notice there are two switches aside. the bottom ones are for the motor. the top two are simply to switch the monitor off while rotating. this monitor (and i guess most modern ones) turns on a built-in degaussing coil when it is switched on. it seems to work almost all the time for me. rotate time is roughly two seconds.

[danny_galaga]

and here is the motor i used . this is a tamiya planetary gearbox kit. i've had it kicking around for years. finally found a good use for it

[Silver]

Thinking about the problem of windows setting all the pins high at boot, there are 2 ways I can see round this:

1) Add a break switch to the circuit, that prevents rotation until booted, then flip it until next time you reboot.

2) Assuming all the pins go high, and not crazy/random - we could simply use 2 pins to control. Only rotate when say pin1 is high and pin2 is low. (Maybe a NOT gate to invert this to use in the circuit). This would prevent the monitor rotating until we specify.

I like 2 best.  The way I see it, if you just stuck 2 power transistors in the circuit with there base/emitter junction connected to the data ports, and the collector/emitter before your AC motor (below the master double-throw switch). Then just have a NOT gate inverting the input to one of the transistors. (There may be an easier way of redesigning the circuit to avoid adding a NOT gate - its been a while since I've done this)

If that worked, you could lose the double-throw switch all-together.

Now, assuming it all works at this point, it means we can tell it to rotate whenever we want - but we don't know which way!. So you can just take the output from your detecting microswitches and feed them into some parallel port inputs for us to detect. (I need to check up which pins we can do this on - 16 and 17 look promising).
 From there we just need to know the orientation of the game - and if we are getting really flash, a front-end that remembers the orientation of the last-played game and puts the FE in that orientation. I'm sure I've read someone else trying to sort this exact problem out in another thread. (Of course we don't have to do this - we could rotate the monitor back to default after each game played so the fe knows nothing about it....)


danny_g if you are up for trying it we should probably crawl before we walk. I forgot to ask - are you running XP? On this web page:

http://neil.fraser.name/software/lpt/

Theres a program called lpt.exe that lets you monitor and set all the pins on your parallel port on the fly. I suggest you throw in a couple of power transistors and stick them in Data ports 0 and 1. Theres a pinout here:

http://www.rfcafe.com/references/electrical/parallel_port_pinout.htm

Obviously you'll have to wire up some pins on a DB25 connector.  Also you may need to set your parallel port to be in SPP mode in your motherboards bios. Also as you are testing you may want to disconnect the parallel port connector until you've booted and set all the pins to off....

PINOUT:

[danny_galaga]

actually on my cab im running win98. but im sure itll be much the same. regards solution 1. you dont want to have to switch something manually! already doing that! so second idea sounds better or maybe a timer...

[Silver]

Well it may be even easier for you then, as I don't think Win98 messes with the parallel port.

You could just do 1 power transistor controlled by the port to jump start a rotation.

[danny_galaga]

i've had another thought on your software parameters. if as you say the computer puts some signals out to test/wake the printer when you're starting up, that needn't be a disadvantage. if you use one of those outputs as the horizontal rotator then that would be perfect. it would mean that you always start with a horizontal monitor when you start up the cab. the vertical rotator obviously would have to be an output that NEVER does anything on start-up. if there IS one!

the only other thing to work out (but i've learnt to live with it) if it's possible is can the front end rotate with the monitor so that horizontal or vertical you are reading right side up? i know ultracade has provision for both orientations. maybe rotating could activate one of two front-ends apropriately aligned?

[danny_galaga]

hey silver, have you made any progress?

[cholin]

It would be nice if you had some sort of remote controller to do that   I think Ive got an idea!

[Silver]

Hey,

Sorry things have been a bit slow on this front - does not look like I'm going to get much of a chance for putting anything into practice physically for a while. Was hoping to throw a motor around for testing from a pc....

If you want to try things yourself I can throw some software together to let you change the outputs from the pc parallel port, but you can use the software listed above for testing.

I plan to get to it, but not for a few months I'm afraid (my whole cab project has been delayed.... )

[danny_galaga]

yeah, im moving in a week or so, i guess i wont be doing anything more for a while. i even have to leave my cab behind 

[danny_galaga]

bump (cos it seems relevant to another query)

so how is the programming going silver? any progress?

[danny_galaga]

just an update on how the monitor is performing. i hadnt seen my machine for nearly two years. ive found that the method of turning the turntable isnt perfect. the rubber on the drive wheel is quite soft and after some use starts to slip on the wooden turntable which is abrading (abrasing? ablating?) the rubber wheel. solution? a strip of foam- that dense foam rubber stuff they use in crafts and stuff (kinda like wetsuit material. whats thats stuff called). the rubber i bought is only about 1mm thick which adds a bit of grip (i never added the facility to adjust the drive wheel) but also is grippy against the rubber wheel regardless. bingo! no more lifting the lid to give the monitor a helping hand (",). of course no sooner had  i done that then everything just went blank! a different prob (ram), which ill post about somewhere else...