Thursday, 21 February 2008

NN DCC Controller

Nick and Nigel present their new DIY low cost simple DCC control handset.



The first model was successfully tested on 4th March.

The NN handset connects to a modified Bachmann E-Z DCC command station. The handset has speed (rotary knob) and direction control (two red buttons) of a locomotive selected on the DCC command station. Function selection is on the DCC command station.

The handset automatically takes over control of the locomotive selected on the Bachmann E-Z when plugged in. Control reverts back to the E-Z when the handset is disconnected. It is possible to wire a layout with a series of sockets in convinient locations, and move the handset between sockets.

The design is deliberately minimalist; many layouts are small with only a handful of locomotives, and a simple control is often the most appropriate option.

If running a layout with only one or two locomotives moving at a time, from a total fleet of less than ten, the E-Z is an ideal command station: Its cheap (£35-£40), compliant with standards(*) and very easy to operate. The weakness is a lack of hand-held controller - the E-Z is too big and gets a bit warm to hold in the hand - hence our addition.

Our handset case could be a lot smaller smaller; we selected this size as a good fit and weight distribution when held in the hand.

The changes inside the Bachmann E-Z require insertion of a few wires, a relay, capacitor, resistor and removing the original "expansion" socket. All are careful soldering jobs rather than reprogramming digital electronics. We'll publish a description of what goes where later.

Total control system cost is well under £50 - the Bachmann E-Z can be bought for around £35, and the additional components are very cheap.

For programming the locomotive DCC chips we suggest a Sprog (£50) connected to a computer and the JMRI software toolkit. Total system cost much lower than most other alternatives, can do all programming tasks (including reading back CV values, identifying decoders) and is far easier to use than programming via a DCC command station.

(*) Footnote, April 2008. We have identified another weakness in the E-Z; it appears to only issue 28 speed steps as the control knob is moved, rather than 128 descrete steps. We've checked this on three E-Z units, including one were we had not opened the case(!), and its completely consistent behaviour. The relatively low number of steps means a locomotive can appear to "notch" up the speed range. With careful decoder programming of inertia (acceleration/deceleration) and use of "half speed" F3 function (most chips support half-speed) when appropriate, this can be masked. But I (Nigel) find it annoying that I cannot make the smallest speed changes. We've been told that this weakness is also present in the original Roco LokMaus handsets, so it looks like its common in budget price trainset controllers. I will see over the next few months whether the notchy control is really annoying and if I will need to upgrade the E-Z to something with proper 128 steps; I know I can fit a similar minimalist handset to a Digitrax Zephyr using its "jump ports", though the basic Zephyr will cost at least 3 times as much as the E-Z.

9 comments:

greybear said...

Looks very useful and very stylish as well. I have considered DCC but not taken the plunge yet. This may change my mind.

Jim Straker

Anonymous said...

Looks good and does the job, but why not use a Roco Lokmaus2? Costs about the same as a EZcommand, but is walkabout, extendable (just plug in another Lokmaus2), has function buttons on the handset and does not need modifying.

Nigel Cliffe said...

Anonymous - A good point about the Lokmaus2.
Personally, I don't like centre-off controllers, and one needs to hold the controller to decide if happy with the shape.
But if you do like centre-off, and can find a Lokmaus2, then it should work fine.

David Long said...

Interesting bit of DIY, Nigel, but I estimate your total cost to be about £100. The nice man at Digitrains will sell you a NCE PowerCab for £90 (NCE price $189.95). All the functionality that you need for small layouts like mine and it doesn't need a booster. I found 28 speed steps irritating with E-Z Command (seems OK in 4mm) but PowerCab does 128 at the push of a button and this seems to make a big difference in our scale with no jumps between steps. I tried the Dynamis but couldn't get on with it. not sure i like the " line of sight" with infra-red - radio ncabs would be preferable but I undertsnad them to be illegal at present in the U.K.

Nigel Cliffe said...

David, don't know where your £100 came from. Cost has been well under £50 per system. The E-Z was £35, and the handset addition came to about £10. (Nick's was a bit more as he had a £4 control knob, whereas mine was under £1!).

Personally I'm not really happy with big complex hand-helds. Though of that class of controller, the NCE appears to be the best designed.

Anonymous said...

This looks great, just what is needed for a narrow long shelf layout where only a couple of trains are running. Are you able to post the details on the modifications and handset? Cheers Steve

Nigel Cliffe said...

For Steve/Anon;

Diagram and instructions on what to chop and what to add will be added when Nick has had time to write them up. But he has a lot of work and other things taking his time at present.

Yes, it really does work nicely with a shelf layout; we've run Clive Road sidings with it (see pictures via 2mm website).


If you want to buy a s/hand example, mine is available with the modification as I really am not using it, and its collecting dust.

Anonymous said...

Nigel, thanks for the offer, however I think I'm going to pull appart my unit completely to create a hand held controller (throttle, fwd/rev, emmergency stop) plus a new faceplate with the loco selectors on it, thus leaving the bachman unit as just the electronics which I can bury under the layout.

Cheers Steve

Chris Nicole said...

Your remote handset does look interesting. I have an EZ command controler already and am using it on a small layout with a couple of locos.

Will you be publishing a 'recipe' for your handset ?

Regards,

Chris Nicole