DNA Dan's discussion about secret drive

[DNA Dan]

I see. So the idea is to have it completely FE controlled so you don't have to manually turn the monitor or push a button.

I want to use this with Hyperspin. I see someone wrote a vbscript called hyperotate. Has anyone tried this? I am sure the person who wrote it did, but not sure if they are still around.

I see that it's mostly been developed with MaLa. Would switching to MaLa for my frontend be better?

[DaOld Man]

>>> I see. So the idea is to have it completely FE controlled so you don't have to manually turn the monitor or push a button.

Well, that was my ultimate goal anyway.

>>>I see someone wrote a vbscript called hyperotate

Ahh, I forgot about Haterot's work. (Sorry HR). I think he did work out a add on to allow Mrotate to work with Hyperspin.
I dont have Hyperspin, so I never tried it.


>>>> Would switching to MaLa for my frontend be better?

I cant say what front end would be best for you. I like Mala a lot, and it is constantly being upgraded and de-bugged by Loadman. I have an older version of it, but I need to download the latest, just to see how much it has changed.

Here is a link to the thread about using Mrotate with Mala. I think Haterot left a comment or two about his work with hyperspin:

http://forum.arcadecontrols.com/index.php?topic=91842.0

[DNA Dan]

Alrighty then. I am currently configured with Hyperspin. So I will give that a go when I get to that point. Hopefully you'll have the USB connection available by then   I will switch to MaLa if the script doesn't work for me. I do like the fact that it shows you what the controls are for the game. I haven't seen anything like that in hyperspin yet.

I am just now purchasing parts. I decided to get some things first so I can measure out for the cab. I know it's sort of backwards by not just building the cab first, but I want to completely mask off the rotating parts. I figure I can make a slim, 2 player cab with ~5 inch bezel all around and have users not even know it rotates. I'm excited to get started! You better have my back if I can't get this thing to rotate!

[DaOld Man]

Alrighty then. I am currently configured with Hyperspin. So I will give that a go when I get to that point. Hopefully you'll have the USB connection available by then   I will switch to MaLa if the script doesn't work for me. I do like the fact that it shows you what the controls are for the game. I haven't seen anything like that in hyperspin yet.

I am just now purchasing parts. I decided to get some things first so I can measure out for the cab. I know it's sort of backwards by not just building the cab first, but I want to completely mask off the rotating parts. I figure I can make a slim, 2 player cab with ~5 inch bezel all around and have users not even know it rotates. I'm excited to get started! You better have my back if I can't get this thing to rotate!

Cool. Cant wait to see your work.
I am trying to get my own circuit built for USB control, but am running into problems with programming the PIC chip.
Here is a link to a kit that you can put together. The chip comes programmed with 16 I/O points.  This is the one I am currently playing around with. I think it will work OK, but Im just trying to a cheaper means. So if you want to go ahead and order one, go for it.

http://www.electronics-diy.com/product_details.php?pid=614&name=USB%20IO%20Board%20Kit%20%28PIC18F2455%20/%20PIC18F2550%29

It is a kit, which means you need a good soldering iron and some soldering and electronics experience.
It doesnt come with a USB cord either, but you can cut the cable off an old mouse and solder it to the board instead of the plug that comes with the kit.

And I got your back man! 

[DaOld Man]

Hmmm. Certainly not as simple as I thought, but I completely understand what you've laid out. So far my setup will need a GM2 motor with bracket and wheel, secret motor driver, two limit switches, a DPDT switch, some diodes and either a rheostat or a PWM controller. A few questions however:

If you are going to use the secret motor driver, then you should go ahead and make it automatic. Its not that much harder to do. I will probably have MRotateUSB ready by the time you are ready for it.
But if you still insist on going manual, then using the secret driver makes it a lot simpler than I have laid out.
I dont have time right now, but I will post a pic later to show how simple it will be using the secret driver.
For one thing, the diodes wont be necessary.


1) What sort of limit switches should I use? Leafs? Also once they are tripped, the rotation needs to be stopped in this position correct? Otherwise I see the switch being tripped, than the switch pushing back an closing the circuit again. What do people use for this? A weak magnet? A bump in the travel? Whatever it is the amount of power in the rotation needs to be able to overcome this in the opposite direction.

If the monitor rolls back off the limit switch with this type of drive, then yes, the motor will turn back on and ram against the limit switch again. You have the possibility of the monitor rocking back and forth constantly.
A magnet to hold it still is a good idea, but the motor has to be powerful enough to overcome the magnet when told to go in opposite direction. If you want to get real fancy, you could devise a brake that would hold the monitor still.
The brake could be  released by a solenoid wired in parallel with the motor. (Motor on= solenoid on = brake released.)

The limit switches have to be big enough to handle the current that the motor draws.
I think that small motor you plan to use doesnt draw much current (Im not really sure, do you have any specs on it?)
If its not over a couple amps you can probably just use the micro switches that are on a Arcade cab push button.
Some people have actually used the push buttons themselves. The monitor disc simply presses the buttons when end of travel is reached.


2) What about the diodes? Where are they connected on the switch? Just between the red and black? Also which ones should I get for the setup with the GM2 motor?

The diodes have to be rated for the amount of current the motor can draw also.
They connect across the limit switch connections. They just supply a bypass method for the current to travel.
Post a pic of your drawing that you plan to do and I can draw the diodes in for you.

3) For the rheostat or the PWM controller, this needs to go between the secret motor driver and the motor leads correct? What about a voltage down regulator? I assume that secret motor drive needs 5v, so can't I just bump the voltage through a second regulator at say 3v and slow the speed?

I put that in my drawing just to make an illustration that it is possible. If you construct the rig so you can use the motor at full speed, this wont be needed, and yes, you can use a variable voltage regulator to control speed too.
It's not as hard as one might think.

Sorry for all the questions. Your help has clarified a lot already.

No problem. Asking questions can shed light for others who are on the fence wanting to take the plunge but afraid they dont know enough to do it.
 

[DaOld Man]

Ok, jumping a little ahead of the tutorial, here is a simple method using a selector switch with the small "Secret Drive".
You could use the limit switches that are on arcade buttons for the limits.
I dont see why this wouldnt work. Looks like it's OK to leave the enable input always high, from the info in the data sheet, but since I dont have one of these drives, you will have to do the testing.
With enabled input high, when the direction input goes low (or 0 volts), looks like the drive automatically dynamically brakes, stopping the motor faster.

[DNA Dan]

You should change your name to "ImDaMAN"!

Exactly what I need. I am going to order some parts today and I'll be starting construction this weekend.

Thanks a bunch! I'll be sure to document the build as I go and post if I need more help.

[DNA Dan]

I forgot to ask about the voltage regulator. If I choose to use something like this:

http://www.bakatronics.com/shop/item.aspx?itemid=383

Where does this fit in the circuit diagram? Does it just go in after the secret motor driver but before the motor on VDC?

Also on the switches, for this to work the switch needs to be continuously held down to break the circuit correct?

[DaOld Man]

You should change your name to "ImDaMAN"!

Exactly what I need. I am going to order some parts today and I'll be starting construction this weekend.

Thanks a bunch! I'll be sure to document the build as I go and post if I need more help.

Thanks for the kind words! Im glad I could help. Cant wait to see your work.

[DaOld Man]

I forgot to ask about the voltage regulator. If I choose to use something like this:

http://www.bakatronics.com/shop/item.aspx?itemid=383

Where does this fit in the circuit diagram? Does it just go in after the secret motor driver but before the motor on VDC?

Also on the switches, for this to work the switch needs to be continuously held down to break the circuit correct?

Im not sure you can use that with the secret drive, but if you could, it would most likely go between the secret drive and the motor. Theres not much information with it, but it says it can go as low as 5 vdc. Isnt your motor 5 vdc? So Im really not sure if you can use this or not.
You could use this instead of the secret drive, since it is a drive in itself.
You would have to go back to the DPDT switch setup I first suggested, im pretty sure.
See if that company will share the hook up instructions before you order it, might save you some effort and money.
Ask them how the DPDT switch wires in to reverse direction.

As for the switches, yes they need to be held down continuously when the monitor is in that switches' position.
If the monitor drifts off the switch, the drive and motor will come back on, unless you have the SPDT switch in the OFF position.
There is yet another way to do this that could use monetary switches. Momentary means that the switch is pushed then then immediately released.
But this method would use two small relays and two push buttons for H and V, instead of the toggle switch.
Wanna see another drawing?

[DNA Dan]

Sure! The constant trigger on the switch poses it's own issues with having to have a magnet or something there to hold the rotation. Maybe this new relay method is better if it just involes tripping the sensor. However, you still need to "brake" the monitor in the correct position.

[DNA Dan]

In all these scenarios, do you have to hold the button down to complete the circuit for the thing to rotate? Or is the SPDT a toggle that stays in that position? I mean what is the nature of that switch? Is it always in the center and you have to toggle it to either side, wait for the rotation, then let go. Or is it a flip the switch, it rotates, then gets killed by the limit switch? I guess what I don't understand is what happens if the switch is in the rotate position and the circuit is opened by a limit switch. Is the secret drive in brake mode like a servo? Is this bad to keep it like this while you play?

And dude, I'm not worthy!

[DaOld Man]

In all these scenarios, do you have to hold the button down to complete the circuit for the thing to rotate? Or is the SPDT a toggle that stays in that position? I mean what is the nature of that switch? Is it always in the center and you have to toggle it to either side, wait for the rotation, then let go. Or is it a flip the switch, it rotates, then gets killed by the limit switch? I guess what I don't understand is what happens if the switch is in the rotate position and the circuit is opened by a limit switch. Is the secret drive in brake mode like a servo? Is this bad to keep it like this while you play?

And dude, I'm not worthy!

Very good questions.
The first circuit with the SPDT switch is a type of switch that is maintained. This means it stays in the position until you flip it again.

When the limit switch opens, it is the same thing as flipping the SPDT switch to the off position. The drive turns off and stays off until you flip the switch to the other position. So even while the switch is in H position after monitor stops, the drive is still turned off by the limit switch being open.

For the latching circuits, the push buttons do not have to be held in. The circuit "latches" on until the limit switch resets it. You could substitute a "spring return to center" SPDT toggle switch for both push buttons. This type switch returns to center by itself when released.

From what I ascertain from the website, the secret drive goes into brake mode when both of its inputs are high (on) or low (off) AND its enable input is high (on).

It wont hurt the drive to be in braking mode all the time, unless something is trying to turn the motor. (By twisting the shaft of the motor).
Basically braking is done by "shorting" out the leads of the motor. When power is removed from the motor and the motor is coasting, it begins to generate current. By shorting this current, the motor gets very hard to turn, thus resulting in a braking effect.
There is no current produced when the motor is not turning.

[DNA Dan]

I think I like the simplicity of the SPDT setup best. Would it be possible to have those limit switches close the circuit (instead of opening it) so that both signals are "high" and the motor would just brake in that position? Is this a possibility so as to not have something to "hold" the monitor there like a magnet? I have seen some servos programmed this way but I think it was a logic board. You can get very precise with logic servos but the cost goes up exponentially.

[DaOld Man]

No, without adding anything else to the SPDT circuit, the limit switches need to be closed when the monitor is not in that position.
However,
According to the Solarbotics data sheet on the secret drive, as long as the enable input is tied to + VDC, both directions can be high or low to apply braking. So with the SPDT circuit, when the monitor reaches end of travel and the limit switch opens, both directions to the secret drive will be low. In my SPDT circuit, I have the drive's enable always tied to +vdc, so this circuit already does what i think you are wanting.

Here is a link to the data sheet:
http://www.hobbyengineering.com/specs/Solorbotics-kit10.pdf

Scroll down to page 9 and study the logic table.
With enable high, both inputs low or both inputs high produces braking.

Now about servos. A servo holds its position because it senses the position and constantly corrects for any drifting.
A DC motor does not do this. When current flows through the motor, it turns.
When current stops flowing, it coasts to a stop.
When power is removed, a DC motor will coast. However, while it is coasting it becomes a generator.
You can short the generator and it becomes harder to turn. But enough force can still turn it.
Unless you put a sophisticated tachometer or encoder on the dc motor and have a drive that can correct the motor for drift, you more or less just have to design your rig around the coasting of the motor.

Decreasing motor speed can cut way down on motor coast, but it also adds to overall time it takes for the monitor to rotate.
You can concentrate on the design of the flag (the thing that is attached to the disc and activates the switches).
A flag that is wide enough to still be activating the switch after the motor is done coasting is one way.
I think you need to design your rig so the monitor cant "back lash", or turn backwards slightly after stopping.
Motor braking may prevent this, provided that the monitor is not running really fast.

Hint:
My next MRotate version is going to have the option of adding an encoder like a mouse opto and wheel (could possible hack a mouse to get it.)
The encoder will count up or down a counter. You will be able to set slow down points along the counts which will allow the monitor to slow to a very smooth stop. Limit switches wont even be necessary to stop rotation, but rather be back ups in case something happens.
But, it will be fully automatic, controlled by the computer, which is something you are not looking for.
Hmmm, a DC brush motor acting like a stepper. I wonder if it will be as precise as the stepper?

[DNA Dan]

Is it a poor practice to use a two position switch when either position is going to partially complete a circuit? For instance if I use the SPDT switch and I have it rotating one way, once the limit switch is tripped it stops. But the switch is still in that position. It would be nice to just have this be a "horizontal" or "vertical" 2 position toggle. But that means there isn't an "off" position. Is that generally a poor practice in electronics?

[DaOld Man]

Is it a poor practice to use a two position switch when either position is going to partially complete a circuit? For instance if I use the SPDT switch and I have it rotating one way, once the limit switch is tripped it stops. But the switch is still in that position. It would be nice to just have this be a "horizontal" or "vertical" 2 position toggle. But that means there isn't an "off" position. Is that generally a poor practice in electronics?

No, it is not bad practice. Using a two position SPDT switch is OK. I just tend to overkill a bit.

The advantage (probably only one) to using a 3 position switch is that if something happens and the motor doesnt turn off when it reaches it's end of travel, it would be nice to be able to turn off the motor to keep it from still trying to turn the monitor.

I dont think I mentioned it earlier, but it is highly important to have some sort of mechanical stop so the monitor disc cannot turn a full 360 degrees. Imagine what would happen if the monitor did 3 or 4 complete revolutions. Cords would be wrapping up and damage would occur to something (probably something expensive). So you need stops a few degrees past 0 and 90. Maybe at 100 and 350 degrees. These stops would be fixed in place and not turn with the monitor. The flag could be made to contact these stops after it contacts the limit switches.
The motor could set there and burn up if it is pushing against one of these stops for very long.
But if your rig is designed correctly the chances of this happening are very slim.

Some scenarios that come to mind would be the flag missing a limit switch (or falling off the disc), a limit switch mechanically failing, or limit switch getting loose and moving outside the range of the flag.
Of course if anything happens you can always kill the power supply by pulling the plug on it.
Or you could make an "emergency stop" switch that would kill power to the power supply or open the V+ to the drive.

An emergency stop method is good practice anyway, because the drive could fail and run the motor all the time. Limits or 3 position switches wouldnt matter then. (Unless the limits were set to cut the power to the motor, like the drawing with the diodes).
Good practice for an emergency stop switch is to have it where anyone can easily find it. And everyone using the cab needs to know how and when to use this switch.

[DNA Dan]

Awesome. So I found the kit instructions for that other PWM board. It can be found here:

http://www.funnykit.co.kr/bemarket/shin/menual/fk804.pdf  I have also seen some prices ranging from $7.99 up to ~$20. The kit is for ages 12+ if that shows any indication of my electronics skills   It's odd because if you go to the futurekit homepage www.futurekit.com, the website has been hacked by someone. Hope it's still available through distributors. Anyway....

For a low cost manual setup, I was thinking the following. The PWM boad powered 9v from power supply. The other end connected to a DPDT 2-way switch, which is in turn connected to the motor with the limit switch feedback loop containing the diodes that you laid out in reply #13. According to the Bakaelectronics link I posted earlier, this board can still operate down to 5v whereas the GM2 motor maxes out at 12v. Since I will be throttling the motor down anyway, I figured I didn't need 12v but 9v would be a happy middle road for both devices to work. I will then have an emergency "kill" button on top the cab wired directly to the VDC+ side coming from the power supply. For the DPDT switch I'd used something like this:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=060-322

Or perhaps something like this:
http://www.cherrycorp.com/english/switches/rockers/rr_rocker.htm

I see they make them in double pole, but they are on/off only. Can I wire this with a jumper to make it On-On?

What about the diodes? This is totally unfamiliar territorry for me. I think the need the Schottky type but I am usure about the amps they can handle and the draw the GM2 has. Also that PWM board is rated 1.5A but the motor can draw this same amount. After accounting for the diodes is that too much being drawn off that board?

Here is some more information about the motor:
http://www.solarbotics.com/assets/datasheets/592.gif

I don't quite understand the current (stalled) figure. Is that how much current it will draw in a shorted out state? That is the only figure that's over 1.5A rating of the PWM board. Also confused how the diodes play into this.

[DaOld Man]

Looks like a pretty neat little drive.
With this drive you wont need the secret drive.
I am attaching a modified drawing of how this motor would probably hook up to your DPDT switch and diodes and the PWM drive.
Note that since the PWM drive will stay on no matter if the monitor is turning or not, you may need to add a simple SPST On-Off switch to kill the power to it. This could also double as an emergency stop switch.

The switch needs to be rated for at least 2 amps.
Similar to this:
http://www.allelectronics.com/make-a-store/item/RS-188/ON-OFF-ROCKER-SWITCH-PREPPED/1.html

Notice that the DPDT switches polarity after the PWM drive. You cannot reverse the polarity of the power feeding the PWM drive, so I dont see any other way to do this.
A similar DPDT switch would be this:
http://www.allelectronics.com/make-a-store/item/RS-180/DPDT-MINI-ROCKER-SWITCH/1.html

For limit switches you could just use "Happ" type push buttons, or the micro switches that are mounted to them.
Or you could get a couple of these, which would be much better to make work with your rig:

http://www.allelectronics.com/make-a-store/item/SMS-196/SPDT-SNAP-ACTION-SWITCH-W/LEVER//1.html

The above limts are rated at 15 amps, which should be plenty good.

Diodes need to be rated for at least 2 amps.
Similar to these 3 amp ones:
http://www.allelectronics.com/make-a-store/item/1N5406S/RECTIFIER-DIODE-3A-600V-CUT/BENT-LEADS/1.html

The above parts can be found just about anywhere. You dont have to use the ones I linked to, the links are just to give you an idea. If you choose all the parts based on 2 amps or more rating, you should be OK.

Please note that you wont have dynamic braking with this setup.

[DaOld Man]

I don't quite understand the current (stalled) figure. Is that how much current it will draw in a shorted out state? That is the only figure that's over 1.5A rating of the PWM board. Also confused how the diodes play into this.

The stalled current is the amount of current the motor draws when the shaft cannot turn, due to a physical restriction.
This should be the very maximum amount of current the motor will ever draw.

If you are talking about the diodes in the PWM drive, looks like the one across the OUT terminals (D3) is to protect the transistor from CEMF when the drive switches the motor on and off. You will see this method used around most inductive devices, such as relay coils and motor armatures. When the inductive device turns off, it generates a back force (alternating voltage) while the magnetism is dying. Unloaded, this voltage can increase to several thousand volts, and even though it only lasts a few milliseconds, it can be enough time to damage silicon devices such as transistors. The diode shorts out the voltage when it is in one phase, preventing it from ever getting over ~0.6 volts. (This is the voltage drop across most diodes).
Im not sure about the D4 diodes function. Maybe it blocks capacitor C1 from discharging through TR1 and the motor?
Diodes D1 and D2 are setup to give the pulses different on and off times. (Look at the wave diagram to the right of the schematic.)

Looks like a pretty simple circuit, but if you have no soldering experience you may want to read up on it first, and practice on some scrap wire. If you dont have a good soldering iron, get one.
Also read up on using heat sinks on silicon circuits while soldering.
The heat sink can be a metal alligator clip clipped to the lead between the point being soldered and the device.
It absorbs most of the heat from the soldering iron to prevent from damaging the silicon part.

[DNA Dan]

That is precisely what I had in mind. Thanks for taking the time to schematic it out. I am not foreign to soldering, but certainly the heat sink was something I would not have thought about. Thanks for the tip.

I ordered the motors and such from solarbotics, however they have a $30 USD minimum. So I ended up purchasing the secret motor drive "just in case" I need to do a plan B. You know reading the instructions for that board again they make mention of using the yellow "enable" wire if you're going to use PWM. I was wondering if this could be useful to add the "logic" function down the road to the setup you just laid out. It seems like if you wire the VDC+ from the power supply to the PWM board (and the secret motor drive), then instead of PWM out to the motor, you connected the output to the yellow lead on the secret motor board you could control it through PWM? I don't know how the ground would play into it, perhaps it would go power supply --> sercret motor drive --> PWM board --> motor. I don't know if you would need to ground on the output side of the secret motor board. (Not sure if it matters). But this should allow the PWM motor control, while supplying constant VDC to the secret motor drive, which could then be controlled through a logic interface. Correct? What are you using for your logic interface from the printer port?

Oh and did you see my comment about the switch? I really like those cherry round ones, but they are listed as ON-OFF. Can't that just we wired with the two jumpers like a regular DPDT switch that is labelled as ON-ON. Or for all intensive puposes are they the same thing?

EDIT: I think I answered my own question regarding the switch. With the on-off, you're missing the third leg to attach to. It needs to be an on-on DPDT 2-way switch. (Or 3-way if I want to incorporate the emergency stop.)

[DaOld Man]

There is no interface between the printer port and the secret drive. The printer port is the interface between the computer and the secret drive.
The inputs of the secret drive connect directly to the outputs of the printer port.
the limit switches connect between the ground of the printer port and the inputs of the printer port.
The printer port has 8 easy to use outputs (pins 2 thru 9). These outputs either put out +5vdc when high, or ground when low. This is perfect for the secret drive.
Pins 18 thru 25 on the printer port are grounds. Pins 10 11 12 13 and 15 are inputs into the printer port.

About your idea for connecting the PWM drive directly to the secret drive enable input:
This should work, as long as you keep the power supply to the maximum limit on the secret drive.
You may have to put a 1K resistor on the output terminals of the PWM drive.
This will pull the - Out high when the TR1 is turned off.
Connect the - OUT terminal to the secret drive enable input. The speed output when you turn the pot knob may be backwards from what the site says, but who cares?

This may be the way to go. Then you can use the previous circuit with the SPDT switch and just the two limits to control rotation. The PWM drive will control the speed of the motor by pulsing the Secret drive through it's enable terminal. Good idea. How about drawing me a diagram with Paint to show me how you would hook it up.

[DNA Dan]

I took your previous circuit diagram and modified it by adding the PWM controller. I thought the yellow wire on the secret drive was a (+) out controlled. Looking back at your comments and the instructions I now see they ground that lead to enable "off". But shouldn't this be (+) from the PWM controller?  I am at a loss for where the (+) out needs to go. Do we even need it to complete the circuit? I guess I don't understand enough about the PWM circuit to place the wire.

[DaOld Man]

The 1Kohm resistor will bring the enable input on the drive high when PWM drive is off. It will be low when PWM drive is on.
Should still work, just that your control on the PWM drive may be backward (turn left increases speed, right decreases).

[DNA Dan]

Why would the control be backwards?

[DaOld Man]

Think about it.
When the PWM drive is turned on, it switches the motor on by connecting the ground to it. (Ground is switched by TR1 on the PWM)
But by using it with the secret drive, when the PWM is on, the enabled to the secret drive is off.
Secret enable is off because PWM is turning on the ground on its out contacts.
When PWM is turned off, the enable on the secret is turned on because it is connected to + through the resistor.
It is working opposite the way the motor would work, if the motor was hooked up to the PWM.
It is inverting the PWM pulse wave.
But it shouldnt make any difference, just your speed control might be reversed. Im not even sure it would be reversed, but it sure looks like it would be. If this is a problem for you, you can add a PNP transistor to invert the signal back.
- Out on PWM would turn on the PNP transistor which would connect the secret enable to +.

Or you can leave out the TR1 on the PWM and connect the drive enable directly to the R4 resistor, where the base of TR1 would connect.
At this point here, the signal would be ON (+) or Off (ground). So no bias resistor (to +) would be necessary.
This would correct the signal to the drive enable.

Check out the attached drawing.

EDit: added another drawing which shows the real board component locations.

[DNA Dan]

Wow. You're a rocket scientist! How do you see these circuits in your head so easily? I mean I really need to think about them to know what's going on. I ordered the PWM kit and some other things. I just need to go to a local Radio Shack and get some wire/connectors. What gauge wire should I use for this?

I modified the drawing a bit to keep it clear in my head. I color-coded the wires to match the secret motor drive. I also made the SPDT switch On-On two-way toggle for my control panel, this introduced the SPST main switch back in the picture.

So if this works, all I would need to do to convert this to a printer port is move D1/D2 and the grounds on the limit switches. Correct?

I know yellow isn't the best color to use for this, but I need to keep this straight!

[DaOld Man]

If I was a rocket scientist we would still be trying to get a monkey in space 

Your circuit looks good. Remember you may need to add two 1 K resistors to D1 and D2 to ground. Not sure if the inputs on the secret drive will "float" or not. They may need to be pulled to ground to keep them from false triggering.
Just keep this in mind if you have any problems with it.

Good luck, and keep us informed!
BTW, you asked about connecting the secret drive to the printer port.
Check out this drawing. Quite a bit simpler, isnt it?

[DNA Dan]

   Yea.. I don't know, maybe it's just a control thing! I would still need to get a printer port card thingy, or scrounge an old computer. I assume speed is controlled through MRotate3 as well?

[DaOld Man]

  Yea.. I don't know, maybe it's just a control thing! I would still need to get a printer port card thingy, or scrounge an old computer. I assume speed is controlled through MRotate3 as well?

Yes, MRotate can pulse forward, reverse, and enable for speed control. But of course you could still use the PWM drive like you currently have planned with MRotate.

I am looking forward to seeing your project come to life. Your idea can be a good option for people who want to use manual operation for their rotating rigs.

[DNA Dan]

The implementation of the manual rotation circuit using PWM can be found in my project announcement thread here: http://forum.arcadecontrols.com/index.php?topic=110471.0

[DaOld Man]

Looks good!
Your work area is almost as crowded as mine LOL.

[DNA Dan]

Whoo hoo! I can confirm that the circuit for the PWM/Secret Motor Drive works! I finally got my stuff from solarbotic (which took 8 days and cost me $10 on a $30 minimum order) and it works flawlessly. I tried both the 5V and 12V molex sources on a power supply from a computer. The PWM board will drive the motor from full speed to a complete stop. It's a fairly sensitive adjustment, but I was impressed with the quality of the potentiometer. It's pretty slick. I have to say though, using the GM3 motor on the 5V plug doesn't really require the PWM. Especially if it's turning a 24" disk like my mechanics is setup. I'm a little at a loss for the size, I don't know how well it will hold up. The specs say it's meant to be operated at 6V without detriment to the motor, but I just don't think that's enough juice for my needs. Running it at 12V with the PWM throttling it seems much better, but I don't know if this will burn up the motor or not over time more quickly.

Anyway, I am super stoked that this worked out! I am waiting on some flange mounted bearings before proceeding on the mechanics side of things. I can however start on the motor arm.

BTW, I am only about 8 hours from Calgary and $10 for such a light package and 8 full business days is simply ridiculous. I would recommend http://www.pololu.com/ or some other source for this setup.