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Rotating monitor - Yet another take
DaOld Man:
--- Quote ---Okay, I see what KOZ 319 did.. interesting routing the logic through the limit switches. I suppose it saves a pair of resistors, since you are only sending the Ports own logic signal back to it rather than pullling the input to the power supply.. another enhancement to the cause.. I am using positive logic to drive the H-Bridge at the moment, but there is no reason I can't decide 0, 1 means go CCW instead of 1,0... and it simplifies the circuit, which I think is where most people are hoping we head with this, the benefits of Opto isolators notwithstanding..
--- End quote ---
The problem I found with doing it this way is that the printer port inputs normally float high. This means to use a high to trigger them, you first have to bring the pin to low, through a resistor. Then you use another resistor to bring the pin back to high when the switch is made. On the 2 computers I have been playing with, the resistance values had to change from one PC to the other. The inputs may make, or may not make. The printer pin looks for a logic 0 9which is around 0 -1.5 volts, i think) to register a low in the memory address.
If the resistors arent calculated correctly, or if the voltage varies a little (noise), then this voltage could change, and swing the input back high.
In my experiments, I have found that bringing the pin low when the switch is made is a whole easier, just requiring a 100 ohm resistor, just to limit current through the pin.
But the program, whichever one we use, must be able to register the pin going low to say the switch is on.
Also taking the pin low requires no outside power supply. Its the easiest and simplest, IMHO.
--- Quote ---My program does brake the motor--(either both leads high or both low brakes the motor on the Secret motor driver kit-- its just a small motor so the stop isn't instantaneous with enough rotational momentum..)
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I had my motor wired like KOZ319 did his. When the switch makes, a normally closed contact breaks the current flow to the motor.
In this situation, when computer boots, all inputs go high for a couple seconds.
This does not brake the motor, because one wire to the motor is open (because of the open switch)..
The motor will turn until the monitor comes off the switch, then the motor will brake.
Your circuit may be different, I need to go back and study it more.
.
DaOld Man:
Heres a quick sketch that might better explain what Im talking about on the input pins:
DoctorWHO:
For your info, there's a bundle, GM3 + Wheel at 10$, you can save an extra buck:
http://www.solarbotics.com/products/gmpw_deal/ ;)
psychotech:
;)
--- Quote ---First, .. ...just get everything working with a switch - it seems (sort of) easy enough to do. It doesn't seem like it would be too tough to make the jump from that to something that interfaces with the computer for automatic rotation which is my ultimate goal.
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Yeah, just what I was thinking ;)
DaOld Man, Thanks for the software, have to try it in the near future..
weisshaupt, that Secret Motor Driver sure looks the part I'll have to buy in a few weeks' time :) And like DaOld Man said, "Your writeup and information is very valuable" ..it's just that I had to get instant gratification, err I mean I had to test the mounting as soon as possible ;)
--- Quote ---At full speed, my monitor would have hit the hard limit and BOUNCED!
--- End quote ---
- That's just the reason I had to install the small wheels, nearly frictionless the monitor started bouncing back from the limits ..not damaging anything but really annoying. With a little added friction, well...
Thank you guys for all the additional info & inspiration !! Feel free to "Hijack" this thread :)
Hopefully this thread serves as a starting point for at least a few people starting with monitor rotation..
I really like how with everyone's contributions here now is
1) a possible mounting/drive method description with more possibilities mentioned in the discussion
2) semi-automatic rotation control descriptions & diagrams for instant gratification
3) software and instructions to add some automation to the switch controlled solution
4) parts list for the drive mechanism and links to additional information
5) software and information on full software control to take the system to the next level
So, yet another take -> yet another getting started with...
I'll be following all the threads mentioned here for sure ;)
Cornchip:
Looks like things will heat up over at Solarbotics if this method takes off. The GM3 motor seems to pack a punch for little cash. That rig really seems to work.
I noticed your rig seems to be a little unbalanced causing the motor to underdrive/overdrive. You might want to try adding some counter weight opposite the heavy spot (I thing the monitor cable might also have something to do with that as well). It might smoothen out the movement. My CRT is also severely bottom heavy...but the balancing wasn't needed as the motor uses a 'worm' drive combined with extra gearing with the sprockets. Still there is a perceptible note change to the sound of the motor as it travels from vertical back to horizontal.
Cornchip.
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