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Old Dec 23, 2012, 11:28 PM
Allways the hard way!
georgy's Avatar
South Africa, GP, Germiston
Joined Jan 2012
411 Posts
Question
Servo-guts as drive in mini sub

Read somewhere a bloke used std servo insides as a drive motor & ecs for his mini sub... can any-one tell me how I can do that?

2nd... looking for details on WTC for 1:144 sub... (pics removed from tread i found!)

Maybe bit off more than i can chew with this little thing (Trumpeter Chinese #33)

Any help to noob appreciated...

George
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Old Dec 24, 2012, 01:01 AM
Registered User
Philippines
Joined Jan 2005
826 Posts
1/144 Trumpeter Romeo RC conversion
http://translate.google.com/translat...om%2Fepg800%2F

strange, the link doesn't take you to the exact page I was looking at.
Just click on the Building Threads to see the Type 33 plus other model sub kits converted to RC.
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Last edited by redboat219; Dec 24, 2012 at 01:08 AM.
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Old Dec 25, 2012, 12:24 AM
Registered User
Mesa Falcon Fld, Arizona, United States
Joined Sep 2004
426 Posts
You can modify some servo guts for driving a standard motor. The one question is what is the reason that you want to do it? If you were like me when I first did it, I could not afford the $30-40 for a small brushed ESC at the time, but now the costs have come down and my income has come up. If that is the reason that you are doing it, then I encourage you to do it. There are two ways of doing it. The first is to use the pot that is with the servo. You will need to get it positioned so that when your stick is in the neutral position there is no output to the motor. Once in place, I would use some glue to keep it there. The other option is to get a small trimmer pot. The type that is meant for making small adjustments and keeping its place. I would recommend the sealed type. Install it the same way that the other pot is installed. The last option is to use two well matched resistors and solder them in a voltage divider configuration (this is all the pot is doing anyway). This should give you a few options to keep it cheap.

If you are not doing it because you are trying to save some money, there is a small esc that I saw a few weeks back that I was thinking about getting for a small project of mine that is about $20USD. I saw it on ebay, and I went to his web site. he does stuff with RC subs already.

Adam
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Old Dec 26, 2012, 03:58 AM
Allways the hard way!
georgy's Avatar
South Africa, GP, Germiston
Joined Jan 2012
411 Posts
hi Adam

Not really a cost saving issue... it just looked like a cool idea... & small enough to fit into that (VERY) tiny space! Got some small brushed esc's, but they are ex-plane & does not have reverse.

Still shopping for some more ideas... especially the WTC for such a small sub.
The idea is to only do a surface runner for now..

Thanx for the help..
George
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Old Dec 26, 2012, 03:13 PM
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Xiaoshan, China
Joined Jun 2006
4,581 Posts
You may want to consider something like Rick @ Scale Model Castings does for his micro sub kits. I have one of his 1:22 Marders & would recommend looking over his site & related photo gallery for some ideas on best to approach your project. His Marder / torpedo kits would probably do the trick but he also does custom work if you're inclined to buy a WTC

http://www.scalemodelcastings.com/Ne...-kit_p_20.html

http://scalemodelcastings.smugmug.co...1528&k=ngpnLsT
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Old Dec 28, 2012, 08:17 AM
Man from Atlantis
Sub culture's Avatar
London
Joined Nov 2003
905 Posts
Something worth bearing in mind if using a servo amplifier as a speed controller. They tend to pulse the output at a maximum of 50% duty cycle, and if analogue at a 50hz rate. That means your motor doesn't see maximum power.

An ESC will give 0-100% duty cycle, and at a frequency rate better suited to good low speed control.
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Old Dec 28, 2012, 10:23 AM
Allways the hard way!
georgy's Avatar
South Africa, GP, Germiston
Joined Jan 2012
411 Posts
Been looking at the "bottom drawer-13"... found a brushed esc & 300 size motor doing nothing... Think this will suit the job better. Will have to make a custom battery pack to suit the space available.

Big thing now is to build a WTC & fit the plastic kit around the WTC. Want to fit all electrics with controls and drive shaft as a stand-alone piece & then fit the scale bits onto that....

PS: Gave up on the type-33 Chinese sub. It's just too small. Got a Trumpeter Seawolf 1:144. MUCH bigger space to work with.

As a sub-noob i thought one challenge at a time

Thanx for the help gents...

George
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