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The first thing I must mention are that these point decoders were designed and manufactured to work specifically with Cobalt point motors but have the added benefit of being able to work with the more commonly known Tortoise slow action point motors. They will not work with solenoid motors such as Peco, Hornby and Seep, nor will they operate Fulgurex point motors - to do so will invalidate the excellent 2 year warranty.

However, if like me you have or are considering changing to slow action point motors, then these decoders are definitely for you - you'll be amazed at both their performance and ease of fitting/programming and they will work 'properly' on both DC and DCC.

My kit:

This review of the Cobalt Ad1 and Ad4 decoders was conducted using DCC Concepts 'Cobalt' and also 'Tortoise' point control motors together with my NCE Powerhouse Pro 5amp DCC control system.

What's different about these accessory decoders?

Well the DCC aficionados out there will no doubt be able to tell you all about train decoders, sound decoders and of course accessory decoders, but the Ad1 and Ad4 Cobalt decoders are more of a specialised product designed specifically to work with Cobalt point motors however, as already mentioned, they will also work Tortoise motors nicely. These decoders should not be considered as general run of the mill 'do-everything' accessory decoders, they're not - they are a specialised decoder for a specific type of point motor.

Alternate applications include any reversible thing using Cobalt or other efficient motors such as crossing gates, perhaps a crane, and semaphore signals. any electronics that responds to direction - LED colour light signals using back to back LEDS, and relays configured with a diode in the drive circuit etc

Also, a considerable amount of thought has gone into the design and construction of this product to enable it to be quickly installed, simple to wire and operate as well as dramatically simplifying what we refer to as programming - see addressing below.

They work equally well on DC or DCC.

Simplicity is a must otherwise it will not be accepted and this, in my opinion, is where the Cobalt decoder scores 10 out of 10 - simplicity in every respect.

What's in the box (or blister pack)?

Ad1 - 1 printed circuit board (pcb) measuring approximately 2" x 1.5" x 0.5"
(1.35mmx 1.96mm x 0.39mm)

Ad4 - 1 pcb measuring approximately 5.5" x 1.5" x 0.5"
142.5mm x 1.96mm x 0.39mm)

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An AD4 Blister Pack

The Ad4 is simply 4 x Ad1's sitting side by side on one pcb and, other than the fact there are four of them, are identical to a single Ad1. The only difference I can find is that the Ad4 only needs one connection from the power supply - be that from the DCC bus or 12vDC, and goes on through the circuitry to feed all four units.

The Ad1 has three x 3mm holes drilled in to facilitate #4 flathead screws for fixing to the baseboard or other area. The Ad4 has three holes in each of the four sections (12 in all) and I think it would be overkill to use them all, but you're spoilt for choice as which to use.

What do they look like?

Well pretty much like any other small pcb containing a variety of electronic components all neatly arranged as we've now become accustomed to from DCC Concepts.

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The Ad1 pcb

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And the Ad4 pcb

At the lower edge are eight screw connectors (coloured green) and marked:
1&2 - TRK - the connections to the track power bus or DC supply;
4&5 - PBSW - connections for Push to make normally off push buttons;
7&8 - OUT - connections to the point motor.
NB connections 3&6 are never used.
Again all neat and tidy with good quality recessed screws but, best of all, no soldering.

I do however have to admit that these screw connectors cause me a problem - it's a finger thing. I find once the screw is loosened I have difficulty in pushing very thin wire into the hole unless I tin the end first or prize open the grip inside the hole which the screw presses down on. It's probably just me, but I'd prefer the push down connectors as fitted on the Cobalt point motor.

At the lower right side is a white slide switch used for programming the decoder in one direction and for normal operating mode in the other.

Be Careful:

I discovered a slight discrepancy with the small brief instruction sheet affixed to the rear of the packet. This label shows the six connections in the wrong order so please ignore the diagram otherwise you may damage your new decoder. The manufacturer is aware and will be rectified on the next print run.

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The incorrect terminal markings on the instruction label

As you can see in the images the correct wiring is printed on the PCB so I suggest you use that to prevent mistakes.


I was torn between several options on how and where to mount the decoders. Should I have them fixed to the specially moulded receptacle on the side of the Cobalt motors; screw them underneath the baseboard adjacent to each point; or have them all in one location? Would it be easier to use double sided tape or to screw them into place?

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Ad1 mounted on a Cobalt Point motor

Addressing / Programming:

This really couldn't be easier, simplicity itself, and is something that even the most recent recruit to the ranks of railway modelling can achieve. I've felt for a long time that some people, especially those afraid of electronic equipment, must inevitably be put off by the apparent complexity and need to programme decoders. The Ad1 and Ad4 score ten out of ten in this respect and Richard and his crew must be congratulated for having made this daunting subject so easy it defies belief. Why don't all manufacturers use such a system?

Let me explain. Ad1 and Ad4 decoders obviously require power to work, which can be DCC power direct from the main bus used to run your trains, or a separate DCC accessory bus - connected simply by the use of two wires as you would with 'droppers'. Alternatively, two wires running from a 12v DC - 1amp wall wart, or transformer, again using just two wires will do the job. The only decision you have to make would be if you had a large number of points on your layout and run lots and lots of trains, maybe then you would be best advised to go down the 12v DC separate supply route which will ensure you always have plenty of power to run your trains.

Now, and this is the best bit for the so called programming of these decoders and applies only to those using the decoders connected to a DCC system - i.e. Addressing is not required when used with DC only.

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Operate/Learn switch:

Having connected your two power wires to the TRK terminal, you connect two more to the OUT terminal and connect these to your point motors 'power in' terminals (1&8 on both the Cobalt and Tortoise). Back to the Decoder where on the bottom right side is a small white slide switch, factory set to the 'Operate' mode. You need to slide this little switch into what is referred too as the 'Learn' mode, you move it down about 1mm, which I found my less than nimble fingers had difficulty doing so I used a small ballpoint pen to push it across - don't use a screwdriver as it may short out the components.

Quite why this mode is called Learn I don't know but its different and in some ways amusing, maybe it's akin to teaching a dog its name and when you call out his name it remembers 'that's me' as a decoder does when you call its name on your DCC throttle.

On your DCC throttle you then enter an address for the decoder, any number 1 - 2044 which is NMRA standard. Slide the switch back to 'Operate' and away you go, so simple I thought I'd missed doing something. You don't have to do any other so called programming, in fact you can't. You cannot alter configuration variables (CV's) on this decoder. Once you've set the address its job done, but of course you can always change the address should you need to do so.

With my DCC set up (NCE PowerPro) it took four button presses to program one decoder. Instructions are also included in the user manual (see link below) for programming with Digitrax, Lenz, ESU and MRC/Gaugemaster Prodigy.

Including cutting suitable wire and stripping the ends it took me all of seven minutes to connect up the decoder, address it and then test it with a new Cobalt. How easy was that?

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Up and running in seven minutes:

Push button operation:

I must confess to being a control panel person which is no doubt my upbringing caused by Dad who built great big panels with huge switches, and part of the enjoyment to me was keeping track of what needed switching and when. The Ad1/Ad4 didn't disappoint in this respect. Two connections are provided (4&5 PBSW) for the connection of a simple two wire hook up to a push to make or normally off push button, sometimes also called a momentary push button - I'm sure you know what I'm talking about, the type where pushing the button down makes a connection and taking your finger off releases the connection.

The ultimate intention on my set up now I've got these, is to have through routing set up via DCC macros on my NCE and individual point control via push buttons on a panel for shunting. Mentioned in the excellent on-line manual is the fact you do not need to address the decoders if using on DC only, well I can go one stage further, if you are using them on DCC but only using a panel to control them (i.e. never going to control them via your DCC throttle) then you don't need to address them in that situation either. This rather defeats being DCC in my eyes but I thought I'd mention it and, for those systems requiring two push buttons for one point on a panel, no problem just hook them up to the same connection (4&5) in parallel.

Almost any switching device can be used with these decoders eg reed switches; micro-switches; relays switched by detectors; computer control systems, as all you need to do is connect the switching device to terminals 4&5 - again spoilt for choice.

LED indication is provided for with some excellent diagrams in the on-line manual.

Wiring considerations:

Talking of wire, due to the low output of these decoders you can use almost any small wire you've got, e.g. alarm wire, telephone wire, 7x0.02wire, etc. It is not necessary to use larger wire. I used alarm wire which had 6 separate wires all nicely colour coded for me which was a doddle.

Will these decoders work other Accessories?

DCC Concepts label the product 'Accessory Decoders' but have designed and manufactured them specifically for their Cobalt point motors, and you can't fault them for that. However, as I've already mentioned, they also work Tortoise and other applications include reversible items using Cobalt or other efficient motorised products such as crossing gates, perhaps a crane, and semaphore signals. any electronics that responds to direction - LED colour light signals using back to back LEDS, and relays configured with a diode in the drive circuit etc. They should not be considered as a general accessory decoder but more of a specialised one for a specialised application, and they definitely don't drive solenoids.

One particularly nice touch I like with this product and the manual is that the makers have given considerable thought to how to use and wire them into a layout but, having done that, they've gone on to design and build these thoughts into their product and then gone that one stage further by putting these into print in their instructions and manual in understandable every day English - Nice one.

Overall impressions:

A well designed and made product, nicely packaged and presented, designed to do a particular job and what I thought would be a chore with connection and programming, turned into a pleasurable and simple experience - it really couldn't have been any easier and I'm confident that anyone who can handle a small screwdriver will be able to connect and programme, sorry address, these decoders in minutes.

Oh, I've not mentioned price. Well the single Ad1 comes in at less than £10 and the pcb of four - the Ad4, are a little over £35, and so are very competitively priced.
In my opinion the build quality means with care they should last a lifetime.


DCC Concepts have also produced a very comprehensive fitting, programming and user manual on their website a copy of which can be obtained at the following link:


I'm obviously not going to be able to let you know how these products perform over any period of time - I've only had them six hours, so I'm now going to rip out all my point wiring, wire these and more Ad1/Ad4's into the layout using the simplified wiring suggested by the DCC Concepts manual, crack on and finish my control panel and set up routing on my NCE Power pro, at which time I'll come back to this Review to complete it - but it may be a while.

Review by Mike (16A)

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