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Rotating monitor construction *Project finished*

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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.  :angry:

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.

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