Macgregor Codamac

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Mike_K
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Re: Macgregor Codamac

Post by Mike_K »

Dodgy Geezer wrote: 21 Apr 2020, 22:48 Now for the difficult bit - trying to make it work with a Kinematic.....
That's like trying to get a finely engineered Mercedes or BMW engine (Kinematic) working with some crappy old Austin Allegro (Codamac). And before you ask, my dad was a BMC then BL dealer, so I know just how bad Austin Agro's were, I've literally driven hundreds of them. And in my books the Codamac was just as bad, if not worse! I think Phil is right, put it out of its misery and make it 2.4Gig. :D

Mike
Dodgy Geezer
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Re: Macgregor Codamac

Post by Dodgy Geezer »

I am very grateful for the information and advice gathered from this forum - the unquestioned world centre of excellence for vintage single channel equipment!

But to advise someone to give up on a piece of machinery simply because it will never work properly is mistaking your audience! Anyone whose hobby has involved saving up every last penny to make an expensive item and then throw it off the top of a hill in a gale has obviously got a different view to the rest of the world about what the word 'impossible' means.

While it is obvious that modern machinery is much more reliable, I see it as a challenge to keep some of the old equipment operating. Boats are a much safer way to run it, of course, which is where this kit will be going.

I assume that the big concern with the Codamac is the sliding switch? The rest of the radio is, I understand, essentially the MR200. Is that thought to be just as bad?

As I said before, the Codamac I have got is essentially new. The PCB and battery case is pristine, and the aerial is smooth, stiff and undented. For an early review, however, I have some concerns!

1 - The box is made from plastic and 0.025" aluminium sheet. This is almost paper-thin, and the back can be easily bent if you are not careful.
2 - The 'quick-blip' button is of much poorer quality than the earlier Macgregors.
3 - I'm not impressed with the way the battery is held in place by jamming a bit of foam over it.
4 - The metal control stick is unscrewed to transit. It screws into a plastic collar, and the treads will easily strip. Worse, there is no fixed location for this collar on the shaft. So if the shaft rotates because the screw is not tight the signal will fail. I wonder if this could be a reason for any bad press it may have?

Plus points are the compact box and a nice ergonomic design for the controls.


I suspect that the combo was originally used in a boat. It came with a Supermac MR60 receiver which had a coating of rust. Odd, for an aluminium box... Opening it up, I found traces of water and corrosion products all over it - but the electronics seemed sound, and it provided power to the relay. Trouble was, the relay was all gunged up with corrosion and wouldn't work. I thought about removing the relay for cleaning, but eventually opted for cleaning in situ, using a pin and hypodermic to clean the relay lever with meths. Once it was freed it worked reliably with a solid 'clack'. I suspect this was used once in a boat, not cleaned and dried after use, got sufficient surface corrosion to stop it working and was then put away and forgotten.

Now I hope that it will get back onto a lake after a 50 year rest....
Dodgy Geezer
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Re: Macgregor Codamac

Post by Dodgy Geezer »

Phil_G wrote: 22 Apr 2020, 14:21 Its ok we're just jiving you Dodgy :D we do plenty of restorations from far worse!
Its a nice example and hats off to you for getting it back to doing its thing where it belongs.

I think the "remove stick for transit" thing is a one-time first delivery idea, I wouldnt use it more than a couple of times. You're right the case is thin and prone to mishandling - but it looks really nice so worth looking after.
Its a common misconception that the complex rudder switch mechanically does the "one-for-right, two-for-left" pulsing, but you'll have realised thats not the case. Its just a two way, centre biassed switch, just like any reeds toggle of the day - which would have been a better, cheaper, easier, and much nicer option.
The RF side of the Codamac is faultless, but the unstable pulser and the horrible switch ruined it for me.
There are a few buttons (RS, Farnell etc) available that look identical but operate much more reliably.
Sponge-retained batteries were the vogue back then, thats just how it was! Many a happy hour was spent chasing foam over a hilltop after a long days soaring necessitated a battery change :D
Aren't Kinematics sequential? So left-stick will be "same turn" and right will be "opposite turn".
When repairing marine gear we find that most of the corrosion is caused by well-intended plastic bags that retain water. Better to allow it to dry!
Let us know how the project progresses, despite the jiving, of course we do like to see restorations :D
Cheers
Phil
Its a common misconception that the complex rudder switch mechanically does the "one-for-right, two-for-left" pulsing, but you'll have realised thats not the case. Its just a two way, centre biassed switch, just like any reeds toggle of the day....

I'd never had one of these before - but now that it's been set up, it provides the following outputs:

stick to the right - single tone is transmitted and held
stick to the left - short short tone is transmitted and halted, then there is a pause, then a tone is transmitted and held.
button pressed - single short tone is transmitted and halted.

That sounds like 'press-release-press' for left to me. of course, I may have put the switch together backwards...


Incidentally, 'one for right, two for left' will work with a compound escapement, not a simple sequential one. The Graupner Kinematic is a simple sequential unit. I would like to be able to use the press-release-press function, which, I presume, means making my own actuator. The modelling magazines and books of the 1950s were full of such mechanisms - nowadays you would do it with a PIC! But I have never actually made my own boat actuator, so I would like to have a go.

Boats used to have some of the most sophisticated remote functionality during the 1950s - there was space for masses of relays and mechanisms, and the model would usually survive anything going wrong. I have seen pictures of radios using telephone dials to send pulses and select obscure functions on boats like raising flags - with a sequential switch on the boat using pneumatic dashpots to prevent initiating each function as they were stepped through by adding a little delay...
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Phil_G
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Re: Macgregor Codamac

Post by Phil_G »

Dodgy Geezer wrote: 22 Apr 2020, 17:32...now that it's been set up, it provides the following outputs:

stick to the right - single tone is transmitted and held
stick to the left - short short tone is transmitted and halted, then there is a pause, then a tone is transmitted and held.
button pressed - single short tone is transmitted and halted.
Thats right, spot on.
Dodgy Geezer wrote: 22 Apr 2020, 17:32That sounds like 'press-release-press' for left to me. of course, I may have put the switch together backwards...
Nope, thats correct!

Dodgy Geezer wrote: 22 Apr 2020, 17:32Incidentally, 'one for right, two for left' will work with a compound escapement, not a simple sequential one. The Graupner Kinematic is a simple sequential unit. I would like to be able to use the press-release-press function, which, I presume, means making my own actuator. The modelling magazines and books of the 1950s were full of such mechanisms - nowadays you would do it with a PIC!
Item P5 on the Archive page of www.singlechannel.co.uk Dodgy
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Mike_K
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Re: Macgregor Codamac

Post by Mike_K »

Sorry if you took my earlier post the wrong way, I knew just what you'd be up against. And it isn't that I don't like MacGregor S/C gear, I've got them all from the early "Aeromodeller" right through to the 1+1, including the Codamac.
macs.jpg
What you've described is exactly how it's designed to work - with a compound motorised actuator (or escapement) and a "quick blip" throttle, it was never intended for sequential actuators like the Kinematic. In fact, you have already done better than many by getting it to work as it was intended. There is the manual for it on Phil and Shaun's Single Channel website if you want to see how they describe the operation.

http://www.mccrash-racing.co.uk/sc/data ... damac2.jpg
http://www.mccrash-racing.co.uk/sc/data ... damac2.jpg

But not all is lost, I think you can use it with a bit of lateral thinking. On a Kinematic you need a long-press to go right, release for neutral, long-press for left, release for neutral, long-press for right etc etc. That is right joystick on a Codamac, it keeps transmitting an "on" when you hold right joystick. To get motor forward, stop, reverse, stop etc you need a short press. That is the quick blip button on the Codamac. So using just right joystick for both right and left rudder and the quick blip for motor control it should work as needed. I've attached the Kinematic manual in case you haven't got it.

Kinematic.pdf
(3.22 MiB) Downloaded 156 times

Cheers

Mike
Dodgy Geezer
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Re: Macgregor Codamac

Post by Dodgy Geezer »

Item P5 on the Archive page of www.singlechannel.co.uk Dodgy...

Ah, that's cheating! I want to do it mechanically, like they had to in the old days .... slipping clutches and Mighty Midget motors... perhaps I will wind my own solenoids...

Here is a useful link for mechanical ideas...
http://160592857366.free.fr/joe/ebooks/ ... CLATER.pdf
Dodgy Geezer
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Re: Macgregor Codamac

Post by Dodgy Geezer »

Thought people might like to see the Mk1 compound actuator I put together to work with a Codamac. The video shows it doing 3 'rights' one after the other, then 3 'lefts' and then 3 'rights' again.

It's running fairly slowly on 4.5v, because it tends to skip positions if I run it on 6v, due to the gear train inertia. This speed would be OK for a displacement boat, but not for an aerobatic aircraft! I have some solenoids on order which will provide a positive stop - but they will take weeks to arrive...

The actuator supports the Codamac stick controls, but not the 'quick-blip' auxiliary control. I have some ideas about doing this mechanically - essentially copying the Kinematic by detecting backward movement using a ratchet - but they will have to wait for the Mk2...

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Phil_G
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Re: Macgregor Codamac

Post by Phil_G »

Wonderful I love it :D
The Climax Unimite had a brass leaf-spring against the transfer gear as a brake. without it the actuator would cycle endlessly... similar in principle to the rattler on compound escapements :)

The instructions (see singlechannel.co.uk Archive) explain how to adjust the brake to prevent skipping:
unimite_brake.jpg


Elmic quick blip was a physical 'logic gate' via a contact on the rotor, if the rotor passed say 45° AND the button/relay was released, then its a quick-blip. For both right and left the button/relay would be operated at the 45° point. (might be 30° not 45° but you get the idea)

On the S/C encoder I found it more reliable to detect quick-blip by saying if the virtual rotor does a 360 with no button press at any of the three pawl stops (left, right, kickup), then its a QB.

IMG_20200426_231559.jpg
Dodgy Geezer
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Re: Macgregor Codamac

Post by Dodgy Geezer »

Bet it's a long time since you heard the clack-clack-clack of microswitches with the hum of a motor in the background. You'll have to add a .wav file to your emulators...!

I like the idea of mechanically braking somewhere in the gear train - ideally just next to the armature, which presumably stores most of the angular momentum. Using a solenoid to apply it at just the right time would be a more sophisticated approach than just suffering the drag of a leaf spring all the time....
Dodgy Geezer
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Re: Macgregor Codamac

Post by Dodgy Geezer »

The Elmic electro-mechanical quick-blip approach sounds as if it could be worth investigating. it's pushing the limits of acceptability for a mechanical solution - but if I can source a rotary switch which takes input pulses to go one step forward, then all I would need would be a contact on the rotor passing through one of the microswitches and Bob's my uncle...
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