Rotating monitor construction *Project finished*

[DaOld Man]

This is to keep a track of my progress (and cost) of building a rotating monitor for a mame cabinet.
I suggest you first read this post by Koz319:
http://forum.arcadecontrols.com/index.php?topic=72638.0
Koz319 gives links to drives you can buy already made, or kits you can put together yourself.
I decided to "roll my own" and build the drive Koz319 linked to:
http://www.bobblick.com/techref/projects/hbridge/hbridge.html

I started by ordering the list of parts that Koz319 listed on his website.
I ordered the parts form Digi-key.
The cost of the parts was $5.83 (US).
This doesnt sound bad, except Digikey added a $5 handling charge, then 8.65 shipping, then state tax, coming to a grand total of $20.65.
This kinda struck me broadside, because the Digi-Key website would not give me a shipping charge until I had placed the order. I usually dont deal with websites that do that, but Digikey is a pretty well known name so I thought it would be ok.
Anyway, I also purchased a printed circuit board from Radio Shack # 276-149.
This is a 1-27/32" by 2-27/32" board with holes in it. It also has a small copper ring around each hole. This is what I will use to mount the parts to. The copper rings are good for soldering the parts to.
I also bought a pack of 4 terminal strips. #276-1388. These have leads that will fit the holes in the board. I will attach power, motor, and control leads to these terminals, when the project is done.

Total cost thus far:
$20.65-- Digikey
$1.99-- PC board
$2.49-- terminal strips
$0.27-- tax at Radio Shack
$25.40 --Total thus far.

I would have come out just as cheap if I had ordered the drive kit that Koz319 has a link to on his site.
The Digikey order kinda left a bad taste in my wallet. I have a probelm with any website charging more for shipping than what the parts cost, especially after adding a handling charge.
If you decide to build your own drive, I highly suggest you try radio shack or other websites for more decent prices on the parts.

Motor:
I had an old 12 volt DC motor in my junk box. I think it may be a windshield wiper motor.
I also had an old AT style computer power supply.
I hooked the power supply to the motor and it worked just fine.
I hooked my digital multi-meter in series with the motor, using the meters 10 amp selection.
The motor draws about 1 amp, which should be ok for the drive.
I let the motor run for several minutes, and it didnt get hot or begin to draw more amps, so i guess I will go with that motor. It also did alright when I reversed it, by reversing the polarity of the wires from the power supply.

Power supply:
I am testing the motor with the AT computer power supply, but I dont think I will go with that. I am considering building a power supply, or buying one, since my ordeal with Digi-key. 

Ok, thats pretty much it for now, just waiting on my drive parts.
Oh yeah, here are some pics of the test setup (AT power supply, motor, and multi-meter).
Also a pic of the Radio Shack PC board and terminal strips.
Notice the amp reading on the meter. The amps fluctuated between 0.60 and 0.79.

[kelemvor]

Wow.  If I had placed an order and foudn out that the shipping and such was 3 times more than the item, I'd have called them up and cancelled it.  I never place an order if I can't see the shipping charge beforehand.  I'd think it'd be somehow illegal to do that since they could just say Ah ha, $100 for shipping and you'd already have ordered...

Oh well.

Good luck.

[bfauska]

Crappy deal with the shipping/handling.  I've never dealt with Digi-key, but I have dealt with Mouser, and have been quite satisfied with their service, although to be honest I've only ordered from them for work and rarely pay attention to the shipping cost so I don't know how accommodating they are of small orders.

BUT, the project sounds really cool.  It seems like there is a post or 2 about rotation each month and finally this month it kept going, everybody is looking into different ways to do it and control it.  It'll be fun to watch all the versions progress. 

I'll be watching intently. 

[Cornchip]

  Digikey has an amazing selection of parts in inventory (the Digikey catalogue looks more like a phone book).  It makes Digikey a premium place to shop. Too bad on the shipping, they should be more up front with the price.

  Your wiper motor looks great. I guess saving it for a rainy day payed off. It kinda looks like a motor that's frequently on Ebay (#320174022091) that spins at 50 RPM which is a good low number to start from vs. the motor that I used that was quite fast. If you get stuck and need a hand adapting your drive method to this motor I might be able to help machine something. Just ask.

 Cronchip.

 

[DaOld Man]

Yep, the shipping kinda put a damper on things, but I wanted to build a drive like Koz319 did, and I figured I would use the parts he listed and the source.
I probably had a lot of the resistors in my junk box. I know I have some 2N222 transistors that would have probably worked for the NPNs, but I wanted to track my costs.

Thanks CC for the offer to machine some parts for me.
I just may take you up on it.

Come to think of it, I think I got this motor from a junk yard years ago when I had an 88 firebird with a bad headlight motor.
This one wouldnt fit, I wound up buying one off ebay I think.
Anyway, the one that fit the bird I remember drawing over 10 amps on a battery charger I tested it on back then. (The charger had a amp meter on it).
But the battery charger probably put out more than 12 volts (it had to be at least 13.8 ).
This would have driven the current higher than the regulated 12 volts.
I was afraid this motor would draw more than the drive can handle (4 or 5 amps), but my test rig showed it is well within the specs.
So if anyone wants to do this project, I suggest you test your motor to make sure it doesnt draw more amps than the drive can handle. I still think a windshield wiper motor would be good. You may have to do some rewiring, because most windshield motors have an internal circuit to make the motor complete its revolution when power is removed. That way it stops in the same spot every time. (Wipers go back down when turned off).

Here is one I was looking at.

http://www.allelectronics.com/cgi-bin/item/DCM-249/400400/POWERFUL_WINDSHIELD_WIPER_MOTOR_.html

Im sorry about the long url, I cant seem to figure out how to make a hyper link on here.

[csa3d]

http://www.allelectronics.com/cgi-bin/item/DCM-249/400400/POWERFUL_WINDSHIELD_WIPER_MOTOR_.html

Sorry about the long url, I cant seem to figure out how to make a hyper link on here.

Code: [Select]

[url=youLinkGoesHere.html]Text to use as link[/url]
which translate to

Code: [Select]

[url=http://www.allelectronics.com/cgi-bin/item/DCM-249/400400/POWERFUL_WINDSHIELD_WIPER_MOTOR_.html]Windwisheild Whiper[/url]
-csa

[DaOld Man]

Thanks CSA, but I cant seem to get it right, must not be holding my mouth right or something..
I will need to work on it more later..

[koz319]

Sorry to hear about your experience with DigiKey.  I thought they might charge a handling fee on smaller orders, I thought I mentioned it.
 
I sort of have a love/hate relationship with them myself.  They carry just about everything, and their order processing is kind of amazing.  I swear they can pick,pack, and ship an order of 50 completely different components in less time than it takes me to find a matching pair of socks.  But their prices are on the high side.  Over time though, they've proven to be super convenient more than once, and the time it can save from having to search through multiple sites can be significant.

But man, paying that much shipping on that small of an order does really stink, sorry.

Mouser is pretty good.  Jameco is good for a smaller selection of stuff.

Anyway, can't wait to see your monitor setup when its complete.

Oh, and for what it's worth, I'm still using an old AT power supply to drive my motor.  It was originally just going to be for testing, but is still going strong 4 yrs later

Oh, and the same bridge circuit can be modified to handle more current if needed just by using bigger TIP transistors, I think there is a mention of it on the page.



Koz

[Lilwolf]

Wow, that sucks.  Reminds me when I purchased a $15 monitor bezel with happs... then ended up they charged me 30 for shipping... and I don't even think I knew until it got here (was a while ago)

My most recent shipping complaint was I bought my wife a pearl (natural pancake black) necklace for sweetest day.  It was 5 days early, so I payed the 10 bucks extra for overnight shipping...  Well, last night I got an email saying they shipped it... WTF?

[mountain]

Digi-key is a great resource but they do charge a $5.00 handling fee for orders under $50. It makes sense from a business stand point though. Imagine what their warehouse must look like. The have hundreds of thousands of parts that are small and have to pick, pack, and ship. If you order only a few parts they probably do not make money on the order.

Looking forward to following this thread. I plan on a rotating project very soon myself.

Good luck! 

[DaOld Man]

I can understand a handling charge for a small order. I just have a problem paying that much for shipping on a package that will probably not be much bigger than the radio shack package i showed a picture of.
Oh well, thats water past the bridge. Just thought I would mention it so everyone else will know what to expect for their budget.
I appreciate you listing all the parts, Koz319.

You know I was just thinking about that headlight motor. If I remember correctly, after some research, I found that these motors operate by raising the headlight until it stops against a mechanical stop. An electronic sensor under the fender senses the motor current going high, and shuts off the motor. When the power is removed from the circuit, the sensor reverses the motor until the motor's current goes high again, bottoming out against the headlight closed stop.
This could be a pretty neat way to go with a monitor rotation device.
It would do away with any limit switches, unless you still wanted some kind of monitor position indication.
I have already started down the road to the H-Drive with my project so Im not going any farther with this new idea.
But if someone else wants to explore this idea, please feel free to do it.
Here's some information: The sensor and the motor both were on a 1988 Pontiac Firebird, with the headlights that come up when turned on, then go down into the hood (actually the fender) when turned off. This may give you some search options for Google or Ebay.
 

[Cornchip]

   Also similar to this in a car is the circuitry to stop a window at it's limits (there are no limit switches in a window regulator?). It's buried in the harness...not the motor. Must be the same 'current going high' setup.

 Cornchip.


  Edit.... This might be called an 'overload relay' or 'Poly Switch' device.

 http://www.megastar.com/products/fusetronic/polyswitch/PDF/usb.pdf

 

[danny_galaga]

Motor:
I had an old 12 volt DC motor in my junk box. I think it may be a windshield wiper motor.

that is definitely a windshield wiper motor. just be wary which wires you hook up as some of the terminals are for the auto-park function. many an apprentice has blown the contacts to pieces when hooking these up to a test bench    although i guess if you are just using the power supply there wont be enough current to cause any real damage...

[roninuta]

I have had good service from Mouser in the past ordering single parts. I have purchased batteries, leds, and other small parts.

From their site:
Minimum Order:
NO MINIMUM ORDER on items normally stocked in our warehouse.

also they have a shipping estimator tool:
http://www.mouser.com/estimateshipping/estship.aspx?sl=0

HTH

[DaOld Man]

Motor:
I had an old 12 volt DC motor in my junk box. I think it may be a windshield wiper motor.

that is definitely a windshield wiper motor. just be wary which wires you hook up as some of the terminals are for the auto-park function. many an apprentice has blown the contacts to pieces when hooking these up to a test bench    although i guess if you are just using the power supply there wont be enough current to cause any real damage...

Actually, the motor I have pictured is not a windshield wiper motor.
Im pretty sure it is a headlight motor. It only has two wires coming out, and it turns forever, change the polarity and it turns forever in the opposite direction.
Notice also the shaft comes out of the end of the motor. This used to have a knob on it, so you can raise or lower the lights by turning the knob, if the motor fails.
Now the link that I posted is a windshield wiper motor, but the site tells how to hook it up to work for what we want (Im pretty sure).
I agree about damaging a windshield wiper motor by connecting it wrong. Thanks for pointing that out, I should have mentioned it in my post.

[DaOld Man]

I have had good service from Mouser in the past ordering single parts. I have purchased batteries, leds, and other small parts.

From their site:
Minimum Order:
NO MINIMUM ORDER on items normally stocked in our warehouse.

also they have a shipping estimator tool:
http://www.mouser.com/estimateshipping/estship.aspx?sl=0

HTH

Thanks roninuta!
That looks like a pretty good supply house. I have it bookmarked for future purchases.

Project Update:
Still waiting on parts from digikey.
I have been considering how I am going to mount the 21" CRT.
After looking at the way Koz319 and Jimbo and others did theirs, Im thinking of using the round plywood or MDF.
Im thinking of cutting a circle out in 3/4" MDF, then mounting the monitor to that.
Whats the best way to cut a perfect circle (not sure of the diameter, guessing about 22 inches)?
Im thinking of attaching my router to a piece of wood (or metal), that will pivot on the center of the circle. Have a pin in a hole in the center, run the router around, lower the bit and go around again, repeat until through the wood. (Kinda like a compass).
This is my first time at something like this, so Im open for suggestions.

[mountain]

A long time ago I had to cut a very large perfect circle. I used a piece if 1/4" MDF about 10" wide and a little bit longer than the radius that I was cutting. I used the little plastic bezel from the bottom of the router as a template to drill the holes on one end. I measured out to where the pivot needed to be and used a small wooden dowel to temporarily secure it to the wood I was about to cut. Worked great!

[bfauska]

Question:

Whats the best way to cut a perfect circle (not sure of the diameter, guessing about 22 inches)?

Answer:

attaching my router to a piece of wood (or metal), that will pivot on the center of the circle. Have a pin in a hole in the center, run the router around, lower the bit and go around again, repeat until through the wood. (Kinda like a compass).

They also sell circle cutting attachments for routers, but I've done many a circle the way you and Mountain describe and with careful measurements from your pivot to the edge of the router bit you can get a dead on circle in a jiffy.

[DaOld Man]

Thanks guys..
That jig from Rockler looks pretty neat. I guess the scrooge is coming out in me, I hate to pay that much. I think I will try the homemade one first.
(I may be wishing I went ahead and bought one.)

[danny_galaga]

Motor:
I had an old 12 volt DC motor in my junk box. I think it may be a windshield wiper motor.

that is definitely a windshield wiper motor. just be wary which wires you hook up as some of the terminals are for the auto-park function. many an apprentice has blown the contacts to pieces when hooking these up to a test bench    although i guess if you are just using the power supply there wont be enough current to cause any real damage...

Actually, the motor I have pictured is not a windshield wiper motor.
Im pretty sure it is a headlight motor. It only has two wires coming out, and it turns forever, change the polarity and it turns forever in the opposite direction.

ah, thats why the current draw was relatively low. i might just point out that windshield motors turn forever one way or the other too. the backwards/forwards motion you see at the wipers is mechanical.  they apparently make good motors for barbeque spits (",)

[koz319]

Thanks guys..
That jig from Rockler looks pretty neat. I guess the scrooge is coming out in me, I hate to pay that much. I think I will try the homemade one first.
(I may be wishing I went ahead and bought one.)

You should be able to make a basic home made jig pretty easily, I would definitely try the DIY method before buying one.   I used a very basic homemade jig when I cut the circles for mine, and they turned out really well. 
If I remember correctly, it took two passes to cut completely through the plywood.

[DaOld Man]

Thanks for the info guys..
I got the parts from Digikey today.
Now Ive got to build the H Drive.
But it may be this weekend before I can start on it, we are having a major outage at the job, so Im working 12 hours a day all week.
I will take some pics and post them as I make progress on it.

[DaOld Man]

Got my parts laid out on the perf board.
I am out of solder, so I got to go to Radio Shack.
Here is a pic, however I decided to lay out the parts a little differently, to save me some jumpers later. My next picture will show that.

[DaOld Man]

The drive is finished! And it works!
I plan to hook it to my digital experimenters board and play around with digital signals to it.
I also intend on hooking it to a nutchip and see what I can do with it.
Here is a pic:
(I tried posting more pics, but I got a "post to large" error, so more pics will follow soon).

[Cornchip]

  Nice work on the H Drive. I still can't wait to try this myself.

 About your pics....try changing the image size to something like 800x600 or even 640x480. It changes the file size from 500kb's to 70kb's. That should help your post sizing issues.

 Cornchip.

[koz319]

Nicely done!

[DaOld Man]

Thank you.
I tried touching each input to power supply positive, using a 10 K resistor, and it works great.
This should allow anyone to use a simple SPDT switch to control it, or two pushbuttons, but one would have to hold the pushbutton until monitor revolution is complete.
Of course you could still use pushbuttons with small relays to hold the input on until the monitor revolution completes.
I am going to play around with it a bit using the nutchip, but I intend my finished product to use the computers LPT port and the program you wrote.
This H Drive is very compact, and it should be cheaper to build than using the relays in my very first drawing, (See this thread) BUT a person needs to have good soldering skills and know a little about electronics before building this H drive. I highly suggest using one of the kits you mention on your site, or the completely put together H drive.
As far as the relays go, if someone can wire a control panel, they should be able to easily wire up the relay drive circuit.
But this H drive only measures about 1 1/2" by 2 3/4" by 1 1/2" deep so it will fit in many tight places where the relay circuit would not.
Here are some datasheets:
TIP125
TIP120
PN2222A

[DaOld Man]

  Nice work on the H Drive. I still can't wait to try this myself.

 About your pics....try changing the image size to something like 800x600 or even 640x480. It changes the file size from 500kb's to 70kb's. That should help your post sizing issues.

 Cornchip.

Thanks Cornchip. I was trying to get better pics with my digital cam so I set it to default. Th eimage size was 2000 something by 1000 something. (I think). Anyway it was the largest the camera could do.
But the pictures look a lot better. Lets see how this one looks:
(H Drive connected to motor and power supply.)

[DaOld Man]

I really like this H drive. I can see several uses for it.
Here is a circuit I drew from paint (sorry, another crappy paint picture).
This picture shows how easy it would be to hook a return to center type switch to the H drive.
Kind of like you did on your cab, CornChip..

[Cornchip]

   Wow...this is looking more interesting. Does this allow me to keep the switch 'as is' and have the ability to auto rotate using koz319's software? (provided you don't try to use the switch and H Drive at the same moment).
 
    Also...is the pdf file from koz319's link the exact screen to make the H Drive with no changes keeping my switch? I think I might just be able to get these parts local to where I am and avoid Digikey.

 Cornchip.

[DaOld Man]

   Wow...this is looking more interesting. Does this allow me to keep the switch 'as is' and have the ability to auto rotate using koz319's software? (provided you don't try to use the switch and H Drive at the same moment). Is that what the diode is for...to prevent the back flow of current?  Also...is the pdf file from koz319's link the exact screen to make the H Drive with no changes keeping my switch? I think I might just be able to get these parts local to where I am and avoid Digikey.

 Cornchip.

I guess Koz319 would be better to answer most of your questions.
But I can see where you could use the computer AND your switches to rotate monitor.
Although the simpliest method would be to add another switch for manual (your switches) or auto (computer). Otherwise your computer outputs might conflict with your switch positions.
 
As for the diode, are you referring to the 5K ohm resistor?
I didnt use a diode in the last diagram, but the 5Kohm resistor is just to protect the H drive inputs by limiting the current flow. This resistor may not even be necessary.
I just havent tried connecting A or B directly to positive because I just didnt want to take the chance..

[Cornchip]

  Opps...I modified that last post. I thought the resistor was a diode. Could a diode protect the computer should the key switch be used at an inopportune moment? One other program that I rotate (Kawaks) would still have to have the switch....or any other emulator not supported. Also I have a Dreamcast that has a few vertical games as well (my monitor has 2 VGA inputs). Hmmm....

 Cornchip.

[DaOld Man]

Here's another crappy paint picture, showing a DPDT switch to switch between the computer and the SPDT switch:
I just squeezed the extra drawing into the first. if you are interested in doing it this way, I will draw a better picture.
The Auto/Manual switch is a maintained switch, it could be hidden somewhere, such as on top of cabinet, or in back, or you may want it next to the SPDT switch.

[Cornchip]

   That's alot to think about. I think I'll build this on my bench first and get the wiring straight before attempting a re-wire of the cab. Thanks DaOld Man for the help.

 Cornchip.

[DaOld Man]

Good luck, just remember to be careful when wiring up the H drive, if you get something wrong, it could fry the transistors.
Please keep us posted on your progress. it might be a good new thread.

[XyloSesame]

When are one of you going to start building these for the rest of us transistor-impaired folks?

[Cornchip]

   I actually consider myself as transistor impaired. I won't let my disability stop me. I'll let you  in my progress as it happens.

 Cornchip.

[koz319]

    Also...is the pdf file from koz319's link the exact screen to make the H Drive with no changes keeping my switch? I think I might just be able to get these parts local to where I am and avoid Digikey.
 Cornchip.

That looks to be the PDF file you could use to etch your own board if you like, if thats what you are after.   The hbridge itself doesn't need to change to support manual switching.  If you have a decent electronics shop in your area , they will most likely stock these components or their equivalents

You should be able to connect external switches and the LPT port - I would definitely use the 'select' method that DaOldMan illustrated, to avoid any conflict between auto and manual modes.  One thing to remember though, if you do use a manual switch, you will still need to manually handle the degauss.

I didn't put a switch on my cab, I just created two shortcuts on my desktop to batch files that call rotate.exe.  One rotates clockwise, the other counterclockwise.   When i click one of the Icons in my quicklaunch bar the screen turns.  (Or the batch files can be called from any other programs.)

When are one of you going to start building these for the rest of us transistor-impaired folks?

A few months back I put out a feeler to see if anyone was interested in having a few of these made, and there wasnt really any interest. 
See this post:

http://forum.arcadecontrols.com/index.php?topic=63216.msg632075#msg632075

If there is any interest now, this could still be done.  A few bucks could be shaved off by not including terminal strips, db25 sockets or parallel cables, just let me know.

but the 5Kohm resistor is just to protect the H drive inputs by limiting the current flow. This resistor may not even be necessary.

IMHO, the current limiting resistor is a good idea here..

I also think DaOldMan has a good point about wiring this yourself.  It's a fairly simple circuit, but if your new to wiring things like this on a breadboard, it may be a little more difficult than it appears at first blush.  Im' mot trying to be discouraging at all, I think anyone should be able to build it with a little patience.    You just may want to have a few extra parts handy. (get a few xtra of each)

Koz

[DaOld Man]

When are one of you going to start building these for the rest of us transistor-impaired folks?

I truly wish I could build these for people, but I really dont have the time. (Maybe this would be a good retirement job for me instead of the wild idea about an arcade.)

I suggest you take Koz319 up on his offer, or order one already built and ready to go:
http://www.pololu.com/products/pololu/0705/

Kox319 has this link on his website also.
27 shucks including shipping aint too bad.

[XyloSesame]

When are one of you going to start building these for the rest of us transistor-impaired folks?

A few months back I put out a feeler to see if anyone was interested in having a few of these made, and there wasnt really any interest. 
See this post:

http://forum.arcadecontrols.com/index.php?topic=63216.msg632075#msg632075

If there is any interest now, this could still be done.  A few bucks could be shaved off by not including terminal strips, db25 sockets or parallel cables, just let me know.

I am very interested; however everything I'm reading warns to not attempt anything without an understanding... and I'm still trying to absorb and understand the workings and application of these devices and motors and their relationships to monitors and arcade cabs. It's a bit overwhelming to a complete novice...