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Complicated Diversions (Rotating Monitor, Yes or No)

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DaOld Man:
I could build a "black box" circuit but I dont have the means to mass produce them.
I guess I would first need to know the volts and max current of the DC motor you will be using, or is the motor to be included in the package?
I am considering building a rotating monitor in my first cab "Benny B's Arcade".
But I think I will use a 21 inch CRT monitor instead of the LCD.
This might require a hefty motor, or one geared slow.
When I build this new baby, it will definitely employ my rotate circuit, and Cornchip has given me the idea to use the nutchip.
It will most likely be awhile before I get to this project but when I do, of course it will be posted here..

XyloSesame:

--- Quote from: csa3d on October 18, 2007, 10:56:57 pm ---Just to throw this out to all the budding hardware developers, I'd pay for an out of the box solution to rotate a VESA LCD mount.  Seems like there are enough people who've switched over to LCD technologies lately that this might be something to look into.  This solution would contain hardware and software in a professional package equivalent to Randy's E-Ice campain in my ideal world.

--- End quote ---

I second that. I'm having trouble wrapping my nut brain around manual rotation, let alone chips and circuit diagrams. This thread, while interesting, has quickly surpassed what little electrical knowledge I have.

Out of the box circuit with motor included would be my pref, and it doesn't even need to be pretty.

csa3d:

--- Quote from: DaOld Man on October 18, 2007, 11:23:52 pm ---I could build a "black box" circuit but I dont have the means to mass produce them.
I guess I would first need to know the volts and max current of the DC motor you will be using, or is the motor to be included in the package?
I am considering building a rotating monitor in my first cab "Benny B's Arcade".
But I think I will use a 21 inch CRT monitor instead of the LCD.
This might require a hefty motor, or one geared slow.
When I build this new baby, it will definitely employ my rotate circuit, and Cornchip has given me the idea to use the nutchip.
It will most likely be awhile before I get to this project but when I do, of course it will be posted here..

--- End quote ---

I might eventually take you up on that when I get to this section, as at least this solution does help solve some of my rotational woahs.  Like I stated earlier though, It would be cool if "the product" shipped with everything you needed to make rotation possible.  Just screw your monitor into the VESA, mount it on a crossbrace that you fabricate, hook it up to your computer (for software implementation), then install the plugin to the front-end of your choice (MALA) and watch the magic.. impress your friends.  After all, this hobby is all about vanity!  :D

-csa

solderguy1:
I think I'm gonna try rotating my 20 inch LCD when build time comes but will probably go manual first.  Maybe have physical hard stops in both directions, a 2lb weight to default to horizonal, and a black pull cord coming out underneath the left bottom side of the CP box (out of sight).  Add a J hook underneath the bottom right side to tie off to and you're all set.

It wouldn't be too hard to automate after that though.  Just use a couple LEDwiz outputs to drive a battery-powered screwdriver (cheap 2 way DC motor) through a buffer.  Have level switches to stop motor action in both directions and use paper clips as J hooks so they will easily bend and let go of the cord if the motor doesn't stop when it should.  QED.

DaOld Man:
Ok before this thread is laid to rest, I thought I would pitch out one more option to people who may not be electrically inclined enough to build a relay or a PLC circuit.

Here is a drawing using a DC motor, two limit switches to stop the motor, two bypass diodes, and a Double Pole, Double Throw switch (DPDT)
At the top of this drawing, I show the back side of a DPDT switch. Notice it has 6 terminals.
To the right is the electrical schematic, which is just a lot easier to draw than the "real to life" drawing on the left.
The DPDT switch is really two switches in one (Double pole). It can be switched to connect a pole to the top terminal, or the bottom terminal. (Double throw).
Each pole switches at the same time.

Switch handle up, left center terminal connects to left top, right center to right top.
Switch handle down, left center to left bottom, right center to right bottom.

In the next diagram, I show the DPDT switch "turned on it's side".
(Left of the diagram is top of the switch)

I wire the top left terminal to the bottom right terminal. I wire the top right to the bottom left. (This forms an "X" on the switch's terminals.)
I then wire power supply negative to top right terminal, power supply positive to top left terminal.
The motor wires to the center terminals.

When you flip the switch, it reverses the current flow through the motor.
Switch up, motor turns clockwise (CW), switch down, motor turns counter clockwise (CCW).
Pretty simple huh?

Now we need limit switches to stop the motor from turning when the monitor reaches the correct position.
I have added two limit switches, both are normally closed.
The CWLS switch opens when the monitor reaches the end of clockwise rotation.
The CCWLS switch opens when the monitor reaches the end of the counter clock wise rotation.

You will also notice two diodes.
These diodes provide a reverse path for the current to flow, when the limit switches are open.

Follow the center diagram. I have drawn a red line to denote negative current flow to the motor, and a blue line to denote positive current flow from the motor.
When the switch is turned to the up or clockwise position, Current flows from the negative power supply, through the right side of the switch, through the CWLS switch, through the motor. Now the line turns blue and the current flows through diode D2 (Because the CCWLS is open until the motor starts to turn), through the left side of the switch, back to power supply positive.
The motor turns until CWLS opens, breaking the circuit and stopping the motor.

Now we flip the switch to "down" to turn the motor CCW.
The current now flows from negative through the left side of the switch, down through CCWLS, up through motor, turning it CCW.
The current flows out of the motor through D1 (remember CWLS is open at start, so D1 provides and alternate path),  around through the right side of the switch, back to power supply positive.
Motor turns CCW until CCWLS opens.

This is just about as simple and cheap way of reversing a motor that I can think of.
It does have its drawbacks though. It is not nor can it be made automatic. (My goal).
Plus you will have to mount a switch somewhere. It will most likely be a "bat handle" switch and wont match your others, although you could hide it.
Also, the switch, the limit switches, and the diodes must all be rated to handle the current of the motor. Also, motor braking cannot be applied, so mechanical stops become a must have thing. (Although I would use them in any design anyway.)

Ok, I'm getting off my soap box now.

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