ESCs and back-emf

ge_rik

ge_rik

British narrow gauge (esp. Southwold and W&LLR)
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I'm beginning to explore the potential of battery power instead of DCC and as I have some 1:40 gradients on my railway I wondered if any of the ESCs designed for railway use incorporate back emf load control?

In my early days of DCC I bought a cheap decoder which didn't have back-emf control and boy did I notice a difference. Although I do tend to 'drive' my locos when doing a full operating session, there are days when I just like to have a train running around on its own while I potter about in the garden or entertain friends and I'm just a bit worried that converting to battery power might mean I will no longer be able to do this.

Rik
 
I don't know if there are ESC with feedack, but the ones I use (20A rated, Hobbyking 2.4 GHz taking 1A) really don't need it. I have steep grades too (1:25) and the speed only varies slightly from up to downhill. Don't forget that with battery you don't have any voltage drops in the rails or the transformer part of the supply to cause speed changes. All speed variations will be due to the armature resistance.
In fact in my latest loco, I have ADDED a 3.3 ohm resistor in series with the motor, so that I do get some speed variation and I have to 'drive' the loco.
 
I use the same ESC as Greg and I sometimes "set & forget" my trains and just watch them trundle around with no problem at all.
I have no idea what grade my inclines are but they quite steep and seem to have no effect on the performance.
If I want to 'drive' my trains I run two of them in opposite directions and use passing sidings to avoid collisions, then I have to 'drive' both my trains.
 
I think the importance of back-EMF very much depends on the particular loco; on an 0-4-0 it's probably much less important, but take the example of my LGB Rugen 0-8-0 (the old green one) which, though very cleverly engineered, has a huge amount of drag on curves from its chassis arrangement. When I bought it, it was fitted with an early LGB chip without back-EMF - even on a flat track, with only a couple of cars in tow and on wide-radius (R3) curves, it still slowed dramatically on the bends. Swapping to a more modern chip (an L, with back EMF) made an instant and quite massive difference.

Jon.
 
Thanks chaps, that's very reassuring. I'll be running 0-4-0 or 2-4-0 in the majority but am also planning to use a Zillertal 0-6-2 chassis to create a Manning Wardle based on the Southwold No.4 Wenhaston.

Rik
 
ge_rik said:
I'm beginning to explore the potential of battery power instead of DCC and as I have some 1:40 gradients on my railway I wondered if any of the ESCs designed for railway use incorporate back emf load control?
Click to expand...

I don't know the specific answer to this about ESCs.

I do know that Massoth are supposed to be bringing out a system where you can drive your existing DCC decoders with battery power and control them via their wireless Navigator. Obviously if the decoders already have back-emf (and most do) then you would keep that.

It might be worth considering if you have lots of existing DCC investment, particularly if you have Massoth Navigators which would be resuable.

The big draw back is that Massoth have still not released the system. I know it was promised for the end of this year, but has been pushed back into next.

There are people on here waiting for the system.
 
Cliff George said:
I do know that Massoth are supposed to be bringing out a system where you can drive your existing DCC decoders with battery power and control them via their wireless Navigator. Obviously if the decoders already have back-emf (and most do) then you would keep that.

It might be worth considering if you have lots of existing DCC investment, particularly if you have Massoth Navigators which would be resuable.

The big draw back is that Massoth have still not released the system. I know it was promised for the end of this year, but has been pushed back into next.
Click to expand...
I did see that was in the offing but I'm beginning to wonder if it will ever appear. I've now invested in a couple of 2.4 gHz transmitter and receiver systems so will press on with that for now. I'm intending to produce a small fleet of battery powered locos but also hang on to my DCC locos as well to give me both options. Maybe by the time I've got my 2.4gHz locos up and running Massoth may have removed the proverbial digit and I can convert the DCC based locos. Mind you, I don't have a Massoth transmitter at the moment - still on MTS

Rik
 
ge_rik said:
Greg
Is this the one you use?
http://www.ebay.co.uk/itm/RC-Plane-...sGames_RadioControlled_JN&hash=item27c6ea4e36 < Link To http://www.ebay.co.uk/itm...mp;hash=item27c6ea4e36

Just wondered what it means by programmable - eg can it be programmed for Cruise control?

Rik
Click to expand...

NO !!!!! That is for a brushless motor - the 3 wires at top give it away.
I use this one for brushED motors:
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9090 < Link To http://www.hobbyking.com/...tem.asp?idProduct=9090

If you search the site you might find it at the German warehouse for less postage.
 
Rik,
Just to confirm, I ran a test. Ran a train down my steep grade - some 1:25, probably average 1:40, then back up, at full battery volts/speed - both directions took 45 secs. This is where the ESC is full on so having no effect and the loco itself is obviously very good at constant speed.

A 2nd test at 1/2 throttle (6V) gave110 sec downhill and 130 sec uphill.

see train here:
http://youtu.be/qxD8oaKOcSk
 
That looks so good Greg all it needs now is a water feature under the Hebel Viadict. :bigsmile::bigsmile:
 
One caveat with non-railway designed ESC's is that not all have full reverse.
Some car/boat type reverse at lower power than forward.
You then need to fit a servo to flip a toggle switch for full reverse.

I run a variety of converted Lehmann 0-4-0's, and some Essel types.

I've recently started to move over to Peter Spoerer's Viper 10
I am quite impressed with my first three for simplicity, performance and price.
The Viper has a cruise control option, though I've not used it yet.
 
gregh said:
gregh said:
NO !!!!! That is for a brushless motor - the 3 wires at top give it away.
I use this one for brushED motors:
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9090 < Link To http://www.hobbyking.com/...tem.asp?idProduct=9090
If you search the site you might find it at the German warehouse for less postage.
Click to expand...
Rik,
Just to confirm, I ran a test. Ran a train down my steep grade - some 1:25, probably average 1:40, then back up, at full battery volts/speed - both directions took 45 secs. This is where the ESC is full on so having no effect and the loco itself is obviously very good at constant speed.
A 2nd test at 1/2 throttle (6V) gave110 sec downhill and 130 sec uphill.
see train here:
http://youtu.be/qxD8oaKOcSk
Click to expand...
Thanks Greg
I did wonder why there were three wires. I'm beginning to get the hang of r/c and battery power but it's a bit of a steep learning curve - the last time I looked at r/c 'digital' meant watches with red LED displays that could only be viewed in the dark.

Those data look very reassuring. I'm intending to use 12v Li-ions so hopefully should get similar results.

Great views of your railway. Love the rail-based shot through the rocks.

Rik
 
Rik.
You might also consider ESC's that have been designed specifically for battery R/C of Large Scale locos.
Usually they will have higher voltage capability.
Silent 20 Khz pwm.
Automatic forward and reverse directional lighting.
Built in sound triggers for compatibility with most sound systems.
Controllable momentum.
Cruise control.
Adjustable start and max speed settings for MU'ing dissimilar locos.
Settable default start direction so you can run locos back to back.
Digital proportional control on a dedicated throttle stick with 36 clicks, giving a far finer control arc than having direction and speed on one stick.
Sure they might cost more than regular single stick ESC's but they do offer a lot more features.
 
Tony Walsham said:
Rik.
You might also consider ESC's that have been designed specifically for battery R/C of Large Scale locos.
Usually they will have higher voltage capability.
Silent 20 Khz pwm.
Automatic forward and reverse directional lighting.
Built in sound triggers for compatibility with most sound systems.
Controllable momentum.
Cruise control.
Adjustable start and max speed settings for MU'ing dissimilar locos.
Settable default start direction so you can run locos back to back.
Digital proportional control on a dedicated throttle stick with 36 clicks, giving a far finer control arc than having direction and speed on one stick.
Sure they might cost more than regular single stick ESC's but they do offer a lot more features.
Click to expand...
Hi Tony
Yes - I have been looking at the Railboss which I think has similar parentage to your fine product, plus it's available in the UK from a chap who lives just up the road from me in Cheshire (http://www.tmmodels.net/Radio Control Pages/Radio_Control_Main_Page.html < Link To TM Models). As you say though, it's a mite more expensive than the non rail specific alternatives. It looks like the HobbyKing is around £10, the Viper Loco is around £25, the Railboss is £50 while the Mac5 is £60.

I think what appeals to me is that your system and Railboss make full use of the 2.4gHz channels and as I tend to do a lot of shunting I'm wondering if it might suit my operating style. I just need to evaluate the cost benefits of each system. Unfortunately, cashflow is a bit tight at the moment so I may have to sell off some surplus kit to fund my experiments.

Rik
 
Hi Rik.
Don't forget that to the £10 for the Hobby King you have to add the cost of reversing the direction. That will bring it on line with the price of the Viper.
Then to get 4 x sound triggers for those ESC's you have to add extra parts which in all likelihood will add to the cost and bring the cheapies in line with the Mac5, RailBoss and my RCS stuff. Even then you still won't have directional lighting and still have speed and direction on just one stick.
Let alone the programmable operating features such as speed matching different locos.:kiss:
 
ge_rik said:
MRail said:
I've recently started to move over to Peter Spoerer's Viper 10
Click to expand...
Rob
Is this the one you've been using - which seems to be for railway use?
Rik
Click to expand...
Sorry for the late reply.
It looks identical, apart from the name.
The version I have from Peter Spoerer is called the Viper 10.
It is rated for 14.4V.
Details on:-
http://www.peterspoerermodelengineers.com/90275/info.php?p=3
Just in process of fitting one to a LGB pigsnout railbus for a disabled friend.
Using the blue packed Li Ion battery @ 12.6V with a Spektrum DX 4 RC.
 
ge_rik said:
Rob
Is this the one you've been using - which seems to be for railway use?
http://shop.huntersystems.co.uk/mic...e-speed-control-with-cruise-control-164-p.asp < Link To http://shop.huntersystems...uise-control-164-p.asp
Click to expand...
Rik, now I've looked at it closely, yes it is the same one!
I've scanned the front of the data sheet:-
0f036ac9dad042669a08bfbef79d8f1e.jpg


Peter Spoerer sells it at £22 + post.
Compact enough to fit on the railbus floor between the seats.
 
Thanks Rob. I looked on his website and the info is unclear - the spec for the Viper 10 didn't mention cruise control so I wondered if this was the one. I'm finishing off another couple of projects and aim to investigate r/c and battery power more fully over the winter. I've got a load of info from this thread so I think the next stage is to experiment with a range of options until I find the one which best suits my needs and my pocket.

Rik
 
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