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[dodgy geezer]

I think you'll find high frequency digital storage scopes are needed to pick up that stuff.

100MHz are cheap - Gigahertz less so... :(

Next best pondside tech toy after a handheld scope is a dc current capable clamp meter. £14.34 is the discounted price for those new to the store. I don't need another, but I checked that is a hall effect type that does d.c.
Some reviewers have not sussed you have to store a reference zero reading before each true reading.https://www.aliexpress.com/item/1005005757085279.html

Shows £20 for me. And when do you need to measure 600A?

[dodgy geezer]

Here are a few pics of the Comet.  First the brushes, and to me they don't look too bad at all.

Brushes don't look too bad - commutator less so.


Check the thickness of the Beryllium copper strip brushes where they contact the commutator. They might be worn thin, and if so could break, then snag on the commutator.
The commutator tends to arc where the brushes cross over to the next section. Annoyingly, this is exactly where the holding tab into the backing paxolin is situated, so the tab conducts heat that makes the paxolin eventually crumble.
Do you fancy making up a new commutator? It's fairly easy if you use a Dremmel to sand the small pieces to size.


The Comet looks like a later one. The earlier Comets did not have the metal armature slices very well aligned, since they were hand-assembled. Yours are quite even.

[HMS Invisible]

100MHz are cheap - Gigahertz less so... :(




Shows £20 for me. And when do you need to measure 600A?

This happened when I posted a link to a dual esc. For my privacy I stripped off the url cookie before posting. As a result everyone sees the default option which can be changed at the page foot. There can be several stocked variations which can mean as little as a more popular colour, or a "pro" option, a carry case or more features. Aliexpress shopping means you have to put in the hours to know the process. So I'd recommend looking through the spec list and comparing with other Aneng meters after hitting the "find similar" button.
 It isn't so much the 600 amp range but frequency counter, true rms etc and you'd pay well over a hundred quid for a dc current type if you needed to rush to a trade counter in an emergency.

[DJW]

Hi Martin


I did run one, the one that's now in parts...  See post 11 above. The other one doesn't feel free enough to spin so I didn't try it.


David.

[dodgy geezer]

An article describing the repair of a set of Torpedo brushgear (which is the same as the Comet brushgear) is available on the web site here. You can see the kind of wear that is typical, and the creation and replacement of the commutator.. Sorry about the dark pictures...

[Circlip]

And beware when dealing with Beryllium Copper.   


 Regards   Ian

[DJW]

Haha...  this was meant to be a not too tricky side project. Now we have at least a few ways listed to cause serious injury by electric shock or poisoning. Well. I did ask for input so no one else to blame..!


Thanks for the brush and commutater refurbish link, ill have a good look over that. I'll also strip that second motor and see what it looks like. Might be able to make up one good motor from the two. We'll see.


Thanks to all.
David.

[dodgy geezer]

Might be able to make up one good motor from the two. We'll see.

No reason why you should not have two good motors. Just need to get some paxolin and spring copper...

[roycv]

Hi Dodgy PM sent
Roy

[dodgy geezer]

Having done a bit of experimenting, I can recommend the use of neodymium to boost the Comet's magnet. I tried a magnet from an old hard drive, and found that I could demagnetise and remagnetise the iron horseshoe easily. All you do to improve the magnetism is stroke the horseshoe with the North pole of the neodymium, going north to south on the horseshoe, about 10 times. To demagnetise, go the opposite way (South to North)...

[DJW]

Hi Dodgy


Apologies for delayed reply.  I tried same with a Neodymium magnet, and got the same result.  A lot easier / safer than playing with 110A in a coil..!  I guess these modern magnets pack such a strong magnetic field.  Anyway, I think the Taycol horseshoe magnet is now stronger than it was so that's better.  Now I need some time over Christmas to get at least one, if not two running.


On another note, the Corona Tx module and Rx arrived, just three wires to get connected to the Fleet Tx system and remove the current RF board.  I know two are +ve and -ve power, anyone know where the PPM signal is best picked up from on a Fleet XP/FM Tx..?  Anyone done this upgrade..?


Best regards
David.

[HMS Invisible]

...
On another note, the Corona Tx module and Rx arrived, just three wires to get connected to the Fleet Tx system and remove the current RF board.  I know two are +ve and -ve power, anyone know where the PPM signal is best picked up from on a Fleet XP/FM Tx..?  Anyone done this upgrade..?


Best regards
David.

I've added Frsky modules. The voltage & signal requirements only needed a soldered-on flying lead to mate with the Futaba style servo plug of the 2.4GHz module.
 If you post decent photos of the Tx pcboard & the relevant Corona instructions then anyone who has fitted 2.4GHz modules to any radio will pinpoint where to solder +,-,& signal.
  If it's a NE5044 encoder based Fleet Tx you probably won't need help beyond interpretation & encouragement after reading the data sheet.

[chas]

I updated my fleet tx some time ago. On the rf circuit board, the one with the crystal socket has the connections. On the right hand side viewed from the bottom of the tx there's a white wire on the right hand side, this is the pulse input. Theres also some handy positive and negative wires on that board to take the power from. I disabled the 40 output by removing the crystal, it still takes a negligible amount of power, not enough to concern us. For me it was a good opportunity to replace the batteries, they need to be disconnected before starting anyway. It didn't take long to do and so very well worth doing, they're fantastic bits of kit., 40 plus years old and still no problems at all, not even dirty sticks unlike my Spektrum stuff.

[DJW]

Thanks for the pointers, I've had a quick look and see the white wire on what I think is the RF board.  (It's connected to the Antennae...) I'm a bit tied up today but will have a little more time over next few days to delve deeper.


I'm having some trouble uploading images to MBMImages, getting a 'Request Denied' when logging in, tried several browsers, same on my phone.  Soon as that's resolved I'll upload an image of the boards in the Tx.  Anyone else having upload issues at the moment..?


David.

[HMS Invisible]

Your XP/FM will be based on the NE5044 encoder. Pin number 11 is
 serial output, so you know where to start looking. The NE5044 data sheet tells you everything  else you need to know. The Corona module instructions will tell you its +/- voltage requirement. It's serial input would probably work directly from pin 11, but you want some resistance between the two.
I shine a light from the underside of a pcboard to trace circuitry from a component side photo. You've only got +/- power, a buffered serial input, antenna, & possibly rf power meter to the rf board.

[HMS Invisible]

Below are the two replies that were not
 backed up when main host pulled the plug.

 I'm pasting from the thread subscriber/poster notification email so the original bulletin board formatting of the quotes has been lost. I'll try to repair that aspect as far as possible then give my brief take on DJW's reading.

Jan 16 at 3:46 PM

Afternoon All


Well, been a busy past month or so with Christmas and all, so as always not as much progress as I'd have liked.


But I can report that one of the the Comet motors has had a rebuild.  Retained all original parts, just cleaned up
really.  Strengthened the magnet using the neodymium magnet approach recommended on this thread which
seems to have worked well. Cleaned up the commutator with wire wool, similar with the main shaft to get old deposits shifted.
Gummed up old oil I think.  Cleaned up the paxolin / tufnol and bearing surfaces with WD40,
 again old oil main issue. The brushes look OK in terms of wear to me, so I cleaned them up and put them back.
Oiled the mail bearing surfaces, WD40 on the commutator / brushes.



Then I powered the motor up with a bench supply, and it's nice and smooth, and quiet, just a hum. 
Definitely sounds a lot better than powering up out of the box.  Runs from 1.5V which I was a pit surprised at.  Happiest around 3V drawing 0.5A no load.
 Just gripping the shaft to add some load pushes current to about 0.6A.  It'll be fine pushing a light 16inch Sea Urchin along I think.


Those two points of light above and below the shaft are the brushes arcing...
 Smells a bit like a hornby train set engine to me from many years ago..!

A couple of times it didn't self start when power applied, had to spin the shaft to coax it to life. 
Is that a known issue..?


Does power consumption look normal for a Comet..?


Best regards to all.
David.

Jan 16 at 4:14 PM

That's a tad higher than i expected, and the reluctance to self start is a lrttle worrying.
 How is it on the recommended 4.5 to 6 volts. I seem to remember that Ron Warring, the 1960s motor tester got .5 amps on 6 volts free running.

[dodgy geezer]

The web site has instruction documents on it, which specify the Comet as 4.5v to 6v, drawing 0.4A when free running.  Don't forget to oil the brushes, otherwise you will get increased wear (and probably poor starting...).

[HMS Invisible]

I'm sure the raised no-load current indicates a raised permanent magnet field strength. It would raise the iron loss figure above 0.4 amp and also  lower the  no-load rpm. The same increase will happen with a physical change to the core steel.
 

[DJW]

Afternoon All

Been busy with a few other projects (and life...) but a brief update.

Thanks for the comments re magnet strength being a potential issue with the Comet no load current draw.  I'll be testing in that direction and will report back.  I think a few images / posts were lost in the recent site hiccups, but here's the current state of the refurbed Comet:



I used the 'brushing' technique with a neodymium magnet, and have ordered a stronger pair to enhance further.

This is the figures I'm seeing at the moment:



Mechanically the motor feels right, bearings are clean and lightly lubed, brushes and commutator are clean.  And under power the motors sounds good.  Starting issues seem to have gone away, maybe the brushes were just bedding in...

Have to admit I'm liking working on the Taycols...  So I bought a Meteor that I couldn't resist on ebay..!  No Idea what I'll end up doing with it.

It runs, but needs a refurb...



And here's a question for you good folks, it came with another motor, and I have no idea what it is:





I should have put a ruler in the pic, it's about 25mm in diameter.  Any thoughts..?

Best regards to all.
David.

[chas]

Eveready Electrotor??. I'll dig out my old mags and have a look.

[dodgy geezer]

Have to admit I'm liking working on the Taycols...  So I bought a Meteor that I couldn't resist on ebay..!  No Idea what I'll end up doing with it.

They ARE fun, aren't they!  And simply made - it should be possible to make a Taycol from scratch on the kitchen table.  If you find anything interesting, or want to do a write up, I'd be happy to add it to the web site...

And here's a question for you good folks, it came with another motor, and I have no idea what it is:

II think Chas has hit it. Here's one on ebay...


https://www.ebay.co.uk/itm/146598382109

[DJW]

Hi Both


Thanks for the 'Electrotor' ID, I'll start looking for detail.  The box pic on ebay helped with voltage range for a start.


And the Comet, well I added a couple of neodymium magnets and the current draw went down 0.3A, a 40% drop ish.  So I think that points fair and square at the loss of magnet strength causing the excess draw and it's worth pursuing re magnetising the original.








And Mr Geezer, I've found the your pages a goldmine for Taycol background, so for sure if I can help by adding any findings, I will. 


Best regards
David.

[roycv]

This is a very interesting thread, love the Taycol motors.  As far as the Comets go there is not much power even when new.  So the boat will only pootle along at best.
I did have some thoughts about using a period motor and maybe driving it from a hidden source which could be done with a drive band with a pulley to the Comet.  The u/j on the Comet driving the prop.
Good news the neodimium magnet worked.
Hi Dodgy, how is the 'Scope?
Roy

[Colin Bishop]

I had a Taycol Asteroid back in the day, a feeble thing even then.

Personally I don't miss the Taycols, they were very crude and inefficient devices. Nostalgia has its limits!

Colin

[chas]

Steam engines are mostly crude and often inefficient, but most of us love them, it's all a matter of taste. The magic of seeing the workings doing their stuff is entrancing..