Use of flywheels with DCC

Discuss your experiences with systems, decoders, installations, wiring, control and any general hints & tips you have found.
Sapper
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Use of flywheels with DCC

Postby Sapper » Tue Sep 22, 2015 5:24 pm

I am considering changing to DCC operation on a small layout and would like to know if it is beneficial or otherwise to have a flywheel fitted to the motor. Certainly on a couple of locos I have fitted with them there is an improvement in performance with analogue electrics.

Any information would be appreciated as I am very much a novice regarding DCC operation but it seems the way forward.

Many thanks

Sapper

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jim s-w
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Re: Use of flywheels with DCC

Postby jim s-w » Tue Sep 22, 2015 5:29 pm

I still think it is.

Cheers

Jim

nigelcliffe
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Re: Use of flywheels with DCC

Postby nigelcliffe » Wed Sep 23, 2015 8:15 am

In various non-UK forums I've looked at, its usually as controversial as using EM flanges in P4 :-)

My view, if the flywheel is correctly fitted and well balanced (ie. working correctly in analogue), then its unlikely to be detrimental to digital running. It is probably beneficial.
But, if the flywheel is off-balance, then there may be bad to awful digital running. I have been handed a loco to "CV tune" which had an out of balance drive (mixture of unbalanced flywheel and I think a slightly eccentric worm-wheel), and the DCC chip was fighting the variable back-emf coming from the drive. It was a near impossible task, the end result was "not as bad as when I started" and a strong recommendation that the owner took the chip out and sorted their mechanism first.

Given a choice between space for either a mechanical flywheel or electronic flywheel (stay alive circuit), I'd fit the stay-alive. The stay-alive has dramatic effects on smoothness of locos at very low speed. It is most noticeable on small four wheeled locos, but I think its still a benefit with 8 or more pickup wheels in contact with the track.


- Nigel

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Tim V
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Re: Use of flywheels with DCC

Postby Tim V » Wed Sep 23, 2015 7:29 pm

I'd say not necessary, in fact I've pulled all the flywheels out. Recipe to wreck motor bearings, and extra noise.

One of those anachronisms that we have moved on from....
Tim V

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Paul Townsend
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Re: Use of flywheels with DCC

Postby Paul Townsend » Thu Sep 24, 2015 4:26 am

Sapper wrote:I am considering changing to DCC operation on a small layout and would like to know if it is beneficial or otherwise to have a flywheel fitted to the motor. Certainly on a couple of locos I have fitted with them there is an improvement in performance with analogue electrics.

Any information would be appreciated as I am very much a novice regarding DCC operation but it seems the way forward.

Many thanks

Sapper

If you fit a flywheel to your motor you need to skim the outside with flywheel rotating. The idea is to ensure the exterior at least is concentric with the motor shaft as a first step towards achieving balance. An unbalanced flywheel will kill motor bearings quickly. After doing this if it still vibrates you may wish to skim the inner face too. Even with a lathe these are tricky operations. I have only ever done it on ancient open frame motors with shafts and bearings a bit meatier than Mashimas etc.

I wouldn't bother with a flywheel on DCC. Use stay alive instead......smaller, lighter and able to mount away from motor and decoder in odd corners and no need to balance anything!

Sapper
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Re: Use of flywheels with DCC

Postby Sapper » Thu Sep 24, 2015 5:18 pm

To those who have answered many thanks for your replies. It looks as though the best course would be to delete the flywheel and have a 'stay alive' bit. As I said I am very much of a novice with DCC; could you enlighten me as to what this/these are and how they fit in the scheme of things.

Many thanks

Sapper

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David B
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Re: Use of flywheels with DCC

Postby David B » Thu Sep 24, 2015 5:47 pm

Can someone point us to these 'stay alive' bits, please?

Roger Howden
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Re: Use of flywheels with DCC

Postby Roger Howden » Thu Sep 24, 2015 7:23 pm

Search for 'DCC Stay Alive Capacitors' on this forum where the topic has been covered.

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grovenor-2685
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Re: Use of flywheels with DCC

Postby grovenor-2685 » Thu Sep 24, 2015 8:54 pm

Nigel Cliffe is our resident expert on stay alive, and his post above included a link to his blog.
Here is a more direct one to a relevant page http://www.nigelcliffe.blogspot.co.uk/2013/07/stay-alive-capacitors-in-2mm-scale.html
Regards

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grovenor-2685
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Re: Use of flywheels with DCC

Postby grovenor-2685 » Thu Sep 24, 2015 8:56 pm

Roger Howden wrote:Search for 'DCC Stay Alive Capacitors' on this forum where the topic has been covered.

eg http://www.scalefour.org/forum/viewtopic.php?f=3&t=2598&p=26088&hilit=DCC+Stay+Alive+Capacitors#p26088
regards

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David B
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Re: Use of flywheels with DCC

Postby David B » Thu Sep 24, 2015 9:18 pm

Thanks, Keith.

For electronic numpties like me, are these things available off the shelf so that they can just be plugged in?

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grovenor-2685
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Re: Use of flywheels with DCC

Postby grovenor-2685 » Thu Sep 24, 2015 11:12 pm

Check out the TCS offerings, they have add on stay alive units, although I think they need a little more work than just plugging in. IIRC they also offer decoders with the stay alive built in. Lenz also do a stay alive but rather more costly. There may well be more.
Regards

nigelcliffe
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Re: Use of flywheels with DCC

Postby nigelcliffe » Fri Sep 25, 2015 8:37 am

David B wrote:Thanks, Keith.

For electronic numpties like me, are these things available off the shelf so that they can just be plugged in?


Yes-ish. As Keith said, some makers have integral stay-alive units, TCS being one of them. But, I'd recommend that you are not guided by what is available in a package, but instead choose the right decoder for your loco. (TCS might be the right choice in some cases, but there are other good decoder makers).

For Ready To Run (RTR) locos with the newer plug connectors connectors (MTC21, PluX), its possible that the stay-alive might go via the decoder socket. But most UK RTR is stuck in the past with the old 8-pin plug.

Unless there is a plug connector, a stay-alive circuit has to be soldered to the side of the decoder, either onto solder pads (easier than it sounds), or onto wires provided by the decoder maker. ESU, Zimo and Lenz all offer this facility on their decoders (in Lenz' case, only on the Gold models). They all offer stay-alive devices of varying complexity to go with their decoders. They all have instructions in their manuals. Some Zimo's have specific circuitry on board which simplifies the DIY construction of modules.

The advantage of DIY construction is distributing the capacitors around a loco into spaces, rather than being stuck trying to find space for a shape a maker has produced.

I wrote a long article on the topic in Scalefour News 185 and 186. The tram loco mentioned in the links above has been in its box for about six months, I took it to Scaleforum, pulled out of box, put onto the test-track and it ran perfectly, no wheel cleaning necessary.

- Nigel

Sapper
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Re: Use of flywheels with DCC

Postby Sapper » Sun Sep 27, 2015 6:44 am

To all of you who have replied many thanks for your answers.

I will do some research but at least I now know what to look for.

Sapper

Knuckles
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Re: Use of flywheels with DCC

Postby Knuckles » Wed Jun 15, 2016 9:11 pm

These 'electronic flywheels' have always appealed to me. I always fit flywheels to my analogue loco's if there is space. When I eventually move to DCC (been mulling for years) Stay Alive units appeal.

Does anyone know of any suitable capacitors that can be bunged in an analogue loco for the time being? I know some have done this and I tried it once but wasted my wonga buying the wrong capacitors. Soldered the two together and everything but the loco refused to move. :/
“He who dares not offend cannot be honest.” Thomas Paine

http://www.shapeways.com/shops/sparksho ... eationsscc
Mostly offering Loco kits & bits in 4mm.
SCC Photon Resin Prints Price list
download/file.php?id=19320

nigelcliffe
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Re: Use of flywheels with DCC

Postby nigelcliffe » Thu Jun 16, 2016 7:48 am

Knuckles wrote:These 'electronic flywheels' have always appealed to me. I always fit flywheels to my analogue loco's if there is space. When I eventually move to DCC (been mulling for years) Stay Alive units appeal.

Does anyone know of any suitable capacitors that can be bunged in an analogue loco for the time being? I know some have done this and I tried it once but wasted my wonga buying the wrong capacitors. Soldered the two together and everything but the loco refused to move. :/


"bunged in" - no. It won't work.

It is possible to add a capacitor based circuit to an analogue loco. You'll need to construct a circuit which is bi-directional and able to charge from the track and discharge to the motor. Its not a terribly complex circuit, but it's also not trivially simple. Things will be weird as the speed control will now be moderated via another circuit within the loco, so stopping/starting the loco will now be very strange. The loco will almost certainly have a fixed "momentum" in relation to the analogue control inputs.

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grovenor-2685
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Re: Use of flywheels with DCC

Postby grovenor-2685 » Thu Jun 16, 2016 8:12 am

A DCC decoder may be a source of suitable circuits, fit the loco with decoder and stay alive and set the CVs so it runs on DC.
The only problem is that at slow speed, when you need it most, the voltage on the capacitor will be low and hence the effect minimal.
Which effect is fundamental to DC control!
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Knuckles
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Re: Use of flywheels with DCC

Postby Knuckles » Thu Jun 16, 2016 9:18 am

Ok, I know some people have done it, the control also I'd expect to be different. I did fit a resistor to an engine once and that was kind of odd, made it smoother and slower running but it was also rather drunk and delayed.
I read that the two capacitors need soldering end on end the correct way to avoid them expanding into your eyes but it just made the engine do nothing.

The reason I asked is because I'm not ready yet to move to DCC so wanted to try a temporary analogue bodge for the time being.

Ok no worries, thanks for your knowledge.
“He who dares not offend cannot be honest.” Thomas Paine

http://www.shapeways.com/shops/sparksho ... eationsscc
Mostly offering Loco kits & bits in 4mm.
SCC Photon Resin Prints Price list
download/file.php?id=19320

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jim s-w
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Re: Use of flywheels with DCC

Postby jim s-w » Thu Jun 16, 2016 9:32 am

I think the thing is on DCC locos are not actually controlled all the time. They basically listen for instructions then follow them until they get another one. So when a loco on DCC is travelling at a constant speed there's no direct control of it. It's just waiting for an instruction to speed up or slow down. A break in power isn't an instruction so it's relatively easy for the decoder to realise it needs to switch to stored energy until it either regains power (and receives another command) or the reserves are exhausted. Because the track voltage is constant the reserves are charged fully as long as the power can flow so it's irrespective of what the loco is actually doing.

With DC it's completely different. How would a decoder know if a change in power supply is due to an electrical break or an actual instruction? (Remember emergency stop on DCC is still a command not just turning the power off). If a loco is crawling along, unlike on DCC, there's no extra power available to charge the reserves.

My advice Knuckles is DCC systems don't actually evolve all that much and things only get more expensive. The reality is you are not really gaining anything by waiting to buy a system later.

HTH

Jim

Knuckles
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Re: Use of flywheels with DCC

Postby Knuckles » Thu Jun 16, 2016 12:04 pm

Ok thanks Jim, that helps and makes sense.

I think at the moment I have good reasons though to wait. This baby 6' x 1' P4 layout is all I have at the moment. Also I currently only have 2 loco's that are P4 and 1 chassis without a body that needs seeing to. And besides that there is all the other types of modelling I'm doing which makes getting one at the moment seem pointless. Got many 00 loco's but don't plan to convert the lot.

The research, questions and musings are all in the hope to make the right choice when I do. By then older systems that may be suitable if I'm fortunate enough may be cheaper too.

Currently I'm thinking of the Zepher Xtra. I don't need the best system for my needs. At least I don't think so. Basically I need function buttons on the control case for sound and smoke, option for extra slaves cabs....and that's about it. Enough ampage to have I dunno, 6 or 7 loco's on the track max at 1 time. Max of 3 in operation and a few sizzling in the yard ready for their next turn.
“He who dares not offend cannot be honest.” Thomas Paine

http://www.shapeways.com/shops/sparksho ... eationsscc
Mostly offering Loco kits & bits in 4mm.
SCC Photon Resin Prints Price list
download/file.php?id=19320


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