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Author Topic: Early pitch controllers/levellers  (Read 4974 times)

redboat219

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Early pitch controllers/levellers
« on: March 10, 2012, 12:36:14 PM »

Before anything else I want you to know I already got an electronic pitch controller/leveller.

I just want to find out more how things were done in the early days of RC submarines.
 I'm particularly interested in those hacked helicopter gyros and mechanical pitch controllers. 
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Davy1

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Re: Early pitch controllers/levellers
« Reply #1 on: March 10, 2012, 06:10:19 PM »

Lots of different methods. (Which often shows that nothing was very good!?)
Potentiometers with weights attached (i.e a pendulum) and going through electronics or connected directly into the feedback pot in a servo. The weights suspended in oil dash pots to damp them.
Meths (or Whisky!) in a cylinder with electrodes to give a varying resistance.
Pendulum paddles rotating in front of photo resistors.
A lot on all these in Norbert Bruggens book.
Nowadays using a  very, very tiny pendulum inside an accelerometer chip.
Gyros give a different control characteristic - not angular measurement.
I remember commenting on one photo of an early level controller by Ron P and saying that it looked like something from a U boat! It did.

David


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Patrick Henry

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Re: Early pitch controllers/levellers
« Reply #2 on: March 10, 2012, 06:37:42 PM »

Ron Perrot used to make the SALCON (submarine automatic level control)...despite it's physical size, it was an amazing piece of equipment back then. Nowadays it's been superseded by several units, all of them tiny little electronic gizmos, but pound for pound the SALCON would be still be a viable piece of kit nowadays.


Photo shows a SALCON, top right.


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Subculture

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Re: Early pitch controllers/levellers
« Reply #3 on: March 10, 2012, 07:08:43 PM »

Most of the current levellers use chips based on a bubble of heated air (look up MEMSIC). The ones based on a micro machined beam/pendulum (e.g.ADXL202), were more common on the first solid state levellers, which first started to appear about 10-11 years ago. The ones based on gas are more rugged. Clever stuff.

When I first got into subs, everyone referred to levellers as SALCON's, much in the way PMMA is often referred to as Perspex

I couldn't get one, as they were out of production, and information was a bit thin on the ground for making your own- the circuits in Norberts book were a bit cryptic to say the least. So I ran without one for a while, fortunately the boat I had ran quite well minus a leveller as it wasn't terribly fast, and was very stable.

The earlier designs were based around analogue  devices, like the 555 timer chips. These days they're mostly based on micro controllers, usually a PIC. Those sort of little wonders didn't really start appearing until the early to mid nineties, and have since, alongside other brands like Atmel and ARM, transformed R/C electronics.

A chap in Germany still does analogue levellers, which are combined with a depth controller. They enable the operator to finely tune the PD loop directly to the boat they're fitted in, but they take a bit of setting up.

merriman

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Re: Early pitch controllers/levellers
« Reply #4 on: March 10, 2012, 08:08:10 PM »

Not much to add to Andy's fine over-view. But, here are shots of purpose built angle-keepers, and an angle-keeper that has been converted from an old Futaba mechanical helicopter rate-gyro:



A collection of various purpose-built angle-keepers: Skip-Asay's excellent unit is the board with the glass dome, two pendulum weight type sensors are in and on the black boxes.



To the left are a fail-safe and an angle-keeper circuit. Why not combine those two functions onto a single board; a compound circuit, one that incorporates both a fail-safe and angle-keeping circuit? Just what you get with Kevin McLeod's ADF. But, that's old-school. He has since produced the ADF-2, which is half the size and replaces the trimming pots with a single set-up button. See how small things have gotten over the decades?



You could not have packaged the gizmo's inside a WTC this tightly five years ago! We owe a lot to guys like Bruggen, Perrott, Asay, Dorey, Weeks ... the list goes on and on.
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sub john

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Re: Early pitch controllers/levellers
« Reply #5 on: March 10, 2012, 08:49:39 PM »

http://www.youtube.com/watch?v=F2hHCRgk8no&feature=channel

Just thought i would post this link up for you to have a look at on sub leveler as it might give you some idea of the size of things 20 years ago
                      
                  Sub John
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Re: Early pitch controllers/levellers
« Reply #6 on: March 10, 2012, 09:57:23 PM »

Surface mount components do make things nice and petite. Just a pain in the doodaa when things do go wrong, then large boards and socket mounted ic's seem ever so appealing!

redboat219

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Re: Early pitch controllers/levellers
« Reply #7 on: March 11, 2012, 12:57:43 AM »

Any photos of the purely mechanical pendulum based level keepers
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merriman

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Re: Early pitch controllers/levellers
« Reply #8 on: March 11, 2012, 01:22:41 AM »

Any photos of the purely mechanical pendulum based level keepers

Enough eye-candy! ... Finish your KILO, damit!

David
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sub john

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Re: Early pitch controllers/levellers
« Reply #9 on: March 11, 2012, 12:18:45 PM »

HI Subculture
  You said that surface mounted  components are so petite they are but much better to use as you can make much smaller PCB boards, and one of the benefits of using SMD components there is not much drilling of holes on PCB for components to go through plus SMD can be a lot more temperature stable because the components are smaller. Yes they can be a pain to repair but i have worked on SMD for so long now its second nature as i used to repair RF electronics so small you could hardly see them some times had to work under magnified glass to repair. When you work under magnified glass hand movements become less jerky any way i found it like that
       All the best John
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Re: Early pitch controllers/levellers
« Reply #10 on: March 11, 2012, 09:02:14 PM »

I agree SMD devices have a number of advantages, but they're still far more difficult to replace components on without the right kit.

One area they seem to be less dependable is power devices e.g. Mosfets. I recently had a brushless ESC (not a cheap one either) dispatch itself via one of the FET's letting out the magic smoke. Wouldn't have minded but the controller hadn't been exactly hammered and wasn't all that old either. Not the first time I've had that happen with these SMD power transistors, I've let to have the same thing happen with through hole mounted FET's.

sub john

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Re: Early pitch controllers/levellers
« Reply #11 on: March 12, 2012, 06:50:30 PM »

HI Subculture
 You said that you had problems with SMD speed controller one of the problems is when the manufactures make these speed controllers they will put a small alloy plate on top of one layer of fets but the next board that is below it just sits on the under side of the board above so what happens is that board can not get rid of the heat through the PCB board above so what happens is the fets get hot and go BANG. Other problem is if you don't drive the gates properly the fets will not give out there best performance end result is they will go BANG!!! under high currant discharge
    sub John
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Re: Early pitch controllers/levellers
« Reply #12 on: March 12, 2012, 07:06:32 PM »

In the case of this controller, it's rated for 25A continuous, I never used it beyond 10A. The FET's have a large pad underneath which is soldered directly onto the PCB- that's the heatsink, and I think possibly part of the problem. I noticed the 'pro' version of the same controller uses a large aluminium heatsink.

The company that made this device is Castle Creations. They've been at the game for a while, being one of the first to come up with relatively inexpensive brushless controllers, and they have a good reputation.

sub john

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Re: Early pitch controllers/levellers
« Reply #13 on: March 13, 2012, 09:38:23 PM »

HI Subculture
    On some of the early speed controllers meaning brushless speed controllers, the high sided drive they used to use P channel power fets and bottom low side would use N channel power fets trouble is with P channel fets the drain to source resistance which they call the RDS is normally higher than the N channel fets so what normally happens is the P channel fets get hotter than the N channels so the P channel fets normally go BANG first and then the hole
thing goes up in smoke, but it you look at the new speed controllers they use high low sided driver chips with charge pump so you can drive high sided fets using N channel fets
 gets round the problem having to use P channel fets.

But you might have been talking about a brushed speed controller, even if it was a brushed speed controller may be it had a H bridge lay out of fets to give forward and reverse. Peak inverse volts is one sure way to blow fets if circuit is not protected against it, but problems like this can be sorted out
 
  John
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Re: Early pitch controllers/levellers
« Reply #14 on: March 19, 2012, 03:35:15 PM »

This controller is only a couple of years old, and is brushless. It uses the same Mosfets for all six transistors, and they are N-channel.

sub john

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Re: Early pitch controllers/levellers
« Reply #15 on: March 24, 2012, 06:35:33 PM »

HI Subculture
    Have had a real problem trying to log in since mayhem went down could not even register at first but at least it works now must have been a pain for Martin to sort out.
   
  You said your speed controller was for brushless motor, some of the early speed controllers soft ware did not run very well problems with start up routine one of the main problems with brushless speed controllers that have forward and reverse you have got to make sure you have stopped the motor before the motor turns the other way or things will go BANG iii   but that might not have been the problem why your's went BANG
      John
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Re: Early pitch controllers/levellers
« Reply #16 on: March 24, 2012, 06:43:14 PM »

The controller was a fairly recent model, and the software is updated fairly regularly. I think I was just unlucky and got a bad component.
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