Model Boat Mayhem - Forum

Please login or register.

Login with username, password and session length.
Pages: 1 [2]   Go Down

Author Topic: using servos to power small models  (Read 6807 times)

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,568
  • Location: Blackpool, Lancs, UK
Re: using servos to power small models
« Reply #25 on: August 07, 2008, 02:43:23 PM »

I did see a very neat arrangement a while back on a Revell Trawler where the charging point and switch were combined by using a small earphone jack as the charge socket.  The charger had an earphone plug fitted.  The switch part was a dummy plug/bung which sealed the hole but allowed the model to be switched on and off using the switch built into the socket, and was at the same time unobtrusive.
The model did get sailed in quite alarmingly lumpy water, and performed very well.
Logged
"With the right tool, you can break anything" - Garfield

warspite

  • Guest
Re: using servos to power small models
« Reply #26 on: August 07, 2008, 07:02:09 PM »

Neat idea, i was wondering how to charge insitu and switch the thing off as well, there are several ventilators dotted about the deck, fitting a nokia sized power socket underneath one of them could a possibility and using two plugs from some of the many spare chargers or adaptors that come with universal chargers nowadays (or visit maplins) to create the elctrical connection and the plug on the bottom of the ventilator horn.

Actually would you need to have two, one to connect the power in series across the pos and neg of the battery and the the other to disconnect the pos lead to the battery from the receiver, or does it not matter that the charger is powering up the receiver as it charges the battery?

 ???
Warspite
Logged

warspite

  • Guest
Re: using servos to power small models
« Reply #27 on: August 07, 2008, 07:41:02 PM »

What about smaller servo's, any recommendations for reasonably good rpm and sufficient torque to push a prop through the water when stripped down?, i suppose they all have different gearing to achieve this and the motors are all the same  :-\

warspite
Logged

warspite

  • Guest
Re: using servos to power small models
« Reply #28 on: August 07, 2008, 09:59:06 PM »

Bunkerbarge

I noticed the gato revell kit is quite large, i assume this is the sub you refer to with two std servo's pushing it along.

Warspite

Am i boring everyone with this?
Logged

riggers24

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 449
  • Just full of stupid questions
Re: using servos to power small models
« Reply #29 on: August 07, 2008, 11:19:49 PM »

Hi there BarrieW

I am glad you put this picture on  O0  because the next time a certain Mr Riggers complains about my wiring being a bit of a mess - I will refer him to your picture - please do not take my comment wrongly - it is all meant in fun.   I do realise working with small models requires wires to be all over the place, but certain folk cannot understand this can they Riggers?  {-) O0 O0 O0

aye
john e
bluebird

Bluebird's wiring what can I say, by the time the model requires all the wiring run he is bored and impatient. Man on galloping horse, Ray Charles could have done better and did you use a catapult to put the wiring in are some of the comments aimed towards John's wiring but he is getting better.  ;)

Riggers

Riggers
Logged
I will finish the crash tender someday - Still got tooo many toys to play with

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,568
  • Location: Blackpool, Lancs, UK
Re: using servos to power small models
« Reply #30 on: August 08, 2008, 12:09:11 PM »

All the standard size servos I have stripped have had about the same size motor.  Miniature and low profile ones need a different size because of space requirements.  The big disadvantage is the short shaft which makes reliable coupling a problem.  Flint springs from dead lighters used to be good, but the last ones I looked at had had a re-design, and were just too large a diameter.  Motors from dead CD players are similarly sized and have similar electrical characteristics AND a longer shaft.  I believe our own Mr FLJ has some suit(!)able ones in stock.
Logged
"With the right tool, you can break anything" - Garfield

warspite

  • Guest
Re: using servos to power small models
« Reply #31 on: August 08, 2008, 11:23:01 PM »

At the moment i am looking to use one of these on a test bed, if it is similar to the maplins low cost motor it apparently can do around 11000 rpm  :-\ , it certainly sound like it is, hopefully with the solid connection fitted to the shaft (one of the linkage connectors you find on aircraft) it will prove to be above to move water in a sink at a greater rate of notes than the servo motor, i do have an old cd drive from an old computer, i wonder if these motors are similar to the tape deck type? :-\
Logged

warspite

  • Guest
Re: using servos to power small models
« Reply #32 on: August 08, 2008, 11:40:11 PM »

Dang picture did not take, found a better one, AA in background
Logged

FullLeatherJacket

  • Guest
Re: using servos to power small models
« Reply #33 on: August 09, 2008, 09:15:06 AM »

http://www.mabuchi-motor.co.jp/cgi-bin/catalog/e_catalog.cgi?CAT_ID=ff_030sa  (It's the 5v version)

http://www.action-electronics.co.uk/pdfs/MOTORS01.pdf

Two for a quid (+ P&P, unless you're going to Ellesmere, Blackpool or Warwick shows.)

FLJ
Logged

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,568
  • Location: Blackpool, Lancs, UK
Re: using servos to power small models
« Reply #34 on: August 09, 2008, 11:36:38 AM »

The old cassette tape deck motors usually have a speed regulator built in.
CD motors are largely compatible with servo electronics.  There is usually a spindle motor, about 1" diameter, a tray drive motor, smaller than a servo motor, and a head drive motor, yet smaller again.  In more modern drives, some or all of these might be replaced by stepper motors, which need a diffent type of controller and are thus of little interest to us.  The motors we are intersted in have just two wires, steppers have more, usually four.
The motors listed by Maplin I am uncertain about, but I suspect that their current requirement under any kind of load would fry the servo outputs.  They probably wouldn't do FLJ's pico controllers any favours, either.
Logged
"With the right tool, you can break anything" - Garfield

warspite

  • Guest
Re: using servos to power small models
« Reply #35 on: August 10, 2008, 01:08:46 AM »

Need to re-assess the motor again, from the cd drive i harvester the three motors, the cd motor had lots of connections and got very hot with 4.8v -       thrown it, the laser motor i saved, but not very fast, the deck motor is quite a large dia and has a reasonable speed.

the craft will only be out for a maximum of 5 minutes   -   if it works

the test run of the motor to prop will take place when i build the test rig tomorrow
Logged

warspite

  • Guest
Re: using servos to power small models
« Reply #36 on: August 10, 2008, 06:10:24 PM »

Well the test rig was built, the picture shows the second set up, the first was the servo connected to the prop, being 1.5mm approx. (my vernier is a manual and made by draper, not bad for the price but you get what you pay for), the flight linkage connector is 2mm i/dia, so it has some play, tried to rough it up a little for the solder, when soldered the connector to the shaft it took a little bit of aligning but seemed reasonable.
I had built the propshaft tube last night using Araldite, so i connected the propshaft to the connector using Araldite, it was out of shape by a small amount, not a problem for the water test, went ok and moved water, but after assessing how much i do not think the boat would move any faster than 10 knots at scale speed - ok in harbour not very good for a simulated attack run at 30-45 knots or even 20 knots cruise speed.

After the test, the solder connection came loose and it would require a serious amount of roughing up to make it work, one of those sleeve connectors prieviously mentioned would be better.

The next test was one of the small cheap motors from maplins, I wired the suppression parts and the servo controller to the motor it ran a lot faster with the forward and revers facility as expected, then i built it into the test rig, note i call it a test rig - bit heath robinson don't you know.

This when tested in water did somewhere closer to the cruising speed, so i am happy with that, now the problem (there always is), malcolmfrary is quite right, the second picture shows a close up of the servo controller, the right han side of the controller shows two items a blue balloon type item and a black block item (capacitors  ??? - yep clueless), this black item gets hot  after test running the set up in the bathroom sink for less than a minute, concerns are that it will generate too much heat in a confined space and might fry the controller in less than the 10 minutes overall time i am looking for (5 minutes realistically).

I have an ACTion speed controller, small black box, P52 on the circuit board, will try this if anyone confirms my suspicions.
Logged

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,568
  • Location: Blackpool, Lancs, UK
Re: using servos to power small models
« Reply #37 on: August 11, 2008, 09:44:39 AM »

Try the maplins motor without the controller, just motor, battery and ammeter.  You need to know how much current the motor will puul at a given loading and voltage.  In turn this will tell you the minimum controller.  Sadly, high performance rarely comes cheap.  If it did we would all be doing it.
The coloured blobs that look a bit like smarties with two legs are capacitors.  Black lumps with three legs are usually transistors of one sort or another.  Black items with many (one, two, three, many....) legs on a controller are probably integrated circuits.  A hot transistor or I/C is generally not a happy item.
Logged
"With the right tool, you can break anything" - Garfield

warspite

  • Guest
Re: using servos to power small models
« Reply #38 on: August 11, 2008, 11:13:01 PM »

sorry still trying to get to grips with the posting of photo's, should have included these
Logged

warspite

  • Guest
Re: using servos to power small models
« Reply #39 on: August 11, 2008, 11:14:35 PM »

still can not get it right
Logged

nick_75au

  • Guest
Re: using servos to power small models
« Reply #40 on: August 30, 2008, 09:12:11 AM »

1/72 Revell S-boat

Not quite servos, borrowed some ideas from the wings crowd
280 gms ready to run, 3 GWS motors 7.2v 380 mAH Lipo battery 10 amp fwd only speed control. Reverse would be nice but would probably sink it anyway
Logged
Pages: 1 [2]   Go Up