Installing a Technobots programmable diesel soundcard with Deltang receivers

Since converting my semi-scratchbuilt Fowler diesel loco from track power to battery powered radio control (see How I converted my Fowler from track to battery power), I have been trying to decide which sound system to install.

I have previously used the rather fine MTroniks DigiSounds module from Peter Spoerer, which uses genuine digitised diesel sounds (see Adding a soundcard to a diesel loco), but I really wanted my two diesel locos to sound a bit different. I then stumbled across the Alan Bond / Technobots programmable soundcard. Although this doesn't use real digitised sounds, I was impressed by the realism of the synthesised sounds it creates in the videos which I found online (eg https://www.youtube.com/watch?v=vsIhu18zT_E ).

The card is neatly housed in a splashproof case as it was originally designed for use in boats.

However, the circuit board was easily removed by undoing four screws.

Although the card has a fairly small footprint, space was tight in my Fowler loco so the first task was to decide where the card could be located. I toyed with the idea of placing two of the 18650 li-ion batteries in the cab as I had done on a previous conversion (see How I converted my Peckett loco to battery power),  however, they would have been more visible in this loco's cab unless I opted for the smaller 14500 batteries - which, of course, would have less capacity and hence would give shorter running times.

Eventually, I decided to install the card in the roof of the cab, where it fitted quite snugly.

The strange protuberances from the ceiling were actually not that noticeable and so I felt I could live with it.

Normally, I locate the speaker under the roof of the cab, to allow the sound to escape easily, but this option was now not available. Fortunately, when I constructed the loco, it was originally equipped with an inexpensive sound decoder and the speaker for this was mounted behind the radiator grille. A suitable 8 ohm speaker was purchased from Maplin (Code L68AA0 and squeezed into the space.

The next decision was how to trigger the soundcard. The Technobots card was designed to fit between a receiver and the ESC (Electronic Speed Controller), the lead from the receiver being plugged into the unit and then another lead (provided) connecting the soundcard to the ESC. The Deltang Rx65b, which is now my preferred receiver, has a combined receiver/ESC on a single circuit board and so the interface between the receiver and the ESC is not accessible. I figured I had four alternative approaches, three of which I tried and one I considered and rejected:

1. Use a Deltang Rx102 receiver and a third party ESC (I had a spare ESC to hand) and connect the card between the two as per the design
2. Find some way of dynamically outputting the motor settings from the Deltang Rx65b to the card
3. Find some way of inputting the PWM signal for the motor from the Deltang Rx65b to the soundcard
4. Use a Deltang Rx102 receiver to control the soundcard and the Deltang Rx65b receiver/ESC to control the loco motor, making sure both were bound to the transmitter.

  1. Using a Deltang Rx102 and a separate ESC

This was by far the easiest option. The Rx102 was bound to the transmitter and a standard servo connector taken from it to the soundcard. The ESC was wired into the system and connected to the battery and the motor. The soundcard drew its power from the ESC and so everything was installed quite quickly.

In addition to the basic wiring, The Rx102 was reprogrammed using a Deltang Prog 3 programmer to that Pin 5 produced a momentary 'off' output (ie 0v) in response to Channel 5 (ie the bind button on the transmitter) (see How to program Deltang receivers). A wire was then soldered to Pin 5 of the Rx102 and soldered to the Aux input pin of the soundcard.

However, although the soundcard operated well, I was very disappointed with the level of control provided by the ESC. It was nowhere near as precise and controllable as the Deltang Rx65b, particularly at low speed. As I really enjoy slow running and shunting operations, this was not really something I could live with. I did consider buying another ESC to see if it provided more precise control, but that would risk shelling out more money and still maybe being disappointed with the outcome.

2. Outputting the motor settings from a Deltang Rx65b to the card

As well as its controllability, another great virtue of the Deltang Rx65 is the number of output pads it provides (12), all of which can be re-programmed. Pad 8 on the Rx65b comes ready-programmed to output Channel 1's servo settings. This was therefore ideal, as Channel 1 is used to control the motor speed. Pad 12 was reprogrammed with my Tx20 transmitter to provide 0v momentary output in response the Channel 5.

However, in practice I ran into a difficulty. While the output from the pad was sufficient to control the sound when the loco was running forwards, in reverse the card emitted a monotone sound unrelated to the speed of the loco. It looked as if, maybe, the 3.3v output from the receiver was insufficient to be detected by the card when running in reverse.

3. Finding some way of inputting the PWM signal for the motor from the Deltang Rx65b to the soundcard

This solution was feasible. The soundcard is designed to receive input from a potentiometer and so an electronic circuit could be designed to take the PWM (Pulse Width Modulated) output for the motor from the Deltang Rx65b and convert it into something which the soundcard could recognise. However, whilst I had access to expertise (Alan Bond (the soundcard developer) and Greg Hunter (of the Sandstone and Termite Railway)) both of whom volunteered to advise, I felt this was making the project too complicated for replication by others. It would also require a separate battery supply (unless I made the circuit even more complicated) and with space at a premium, it looked as if this approach was going to create more problems than it solved.

4. Using a Deltang Rx102 to control the soundcard and a Deltang Rx65b to control the loco motor

In the end, this is the approach I adopted. I get the best of both worlds - the precise control and the host of features which the Deltang Rx65b brings, together with the ease of installation which the Deltang Rx102 provides. Both receivers are bound to the same Selecta channel on my Deltang Tx22 transmitter and so the Tx simultaneously controls both receivers. A 5v regulator circuit (see below) was needed to provide power for the synthesiser part of the soundcard, but this was a lot less complicated to construct than the circuit needed for option 3 above.

Installation

As indicated above, the card fitted neatly into the roof of the cab and the speaker sat snugly behind the radiator grille. All I needed to do now was wire everything up.

The sound synthesiser section of the soundcard normally uses the BEC input from the ESC to power its electronics and so, as I was not connecting it to a standalone ESC, I needed to provide the card with an alternative 5 volt supply. I constructed a simple circuit using an LM7805 voltage regulator and a capacitor following guidance provided online. Greg suggested adding a diode to the 5v output and then inserting a 1000uF capacitor in place of the 0.1uF ceramic capacitor for additional protection, but I didn't have a suitable capacitor to hand.

Source: http://www3.nd.edu/~lemmon/courses/ee224/web-manual/web-manual/lab8b/node6.html

The components were soldered to a small piece of Vero board, together with the wires for connections (red = 12v input, black = 0v (negative), yellow = 5v output).

The board was then shrouded in heatshrink sleeve to avoid accidental short circuits.

The yellow wire from the regulator board was then soldered to the middle pin marked Ch1 on the soundcard board and the black wire inserted into the -ve terminal on the board. Another black wire was also taken from the -ve terminal and soldered to the outermost pin marked Ch1. The JST servo lead provided with the card was inserted into the other Ch1 socket on the circuit board .......

..... and connected to the Ch1 pins on the Rx102 receiver board. A wire was also soldered to the uppermost (signal) pin for Ch5 (ie pin 5) on the Rx102 board and the other end soldered to the innermost (signal) pin nearest the DIP switch block. This carries the signal from the Bind Button (Channel 5) on my DeltangTx22 transmitter to trigger the horn on the soundcard.

The red wire from the regulator board was inserted into the +ve terminal on the board, together with a red wire leading to the on/off switch on the loco. Another black wire from the loco battery negative supply was squeezed into the -ve terminal on the soundcard alongside the other two wires. The pink and purple wires (I like to colour code my wiring) from the speaker were inserted into the speaker terminals on the board.

 The wiring to the speakers and the battery were taped to the back of the cab, the regulator and Rx102 receiver were tucked into the cavity in front of the driver and the board was positioned beneath the cab roof.

After checking that the card and loco were reliably operational, the loco was reassembled, and then taken out into the garden for a test run.

From some angles the soundcard and its wiring are barely visible (I've just noticed that the nameplate has fallen off ...... must be lurking in the undergrowth somewhere).

The wiring was a little more obvious from another angle ..... so maybe I will site the batteries in the cab after all.

Yes, the spaghetti is somewhat in your face (well the driver's) while a couple of 14500 batteries will be barely visible.

But, for the time being, ...... the proof of the pudding ..........

I turned the volume on the card down to about a quarter of its full setting in the video. The unit is designed to be heard across a large boating pond and so the sound does carry quite well across the garden (and into the neighbours'). Technobots market a smaller unit (at about half the price), which doesn't have the full programming features but does seem to have a similar sound to the one I selected on this unit. It also can be tailored to have 2-6 cylinders, which makes it sound (sorry) quite attractive should I decide to build another diesel loco (I have another motor block sitting on the shelf....).

In the meantime, I am more than pleased with the way this unit behaves. And if ever I get tired of this particular engine sound, I can always reprogram it at no extra cost!

UPDATE - 20/10/15
 I decided that the clutter in the cab was unacceptable and so re-positioned the card and associated electronics in the engine compartment. I left one of the batteries in the compartment  .....

...... and placed the other two in the front corners of the cab, painted dark brown to match the console.

The batteries are hardly noticeable .......

..... a lot less obtrusive than the electronics and wiring were. (Still not found the missing nameplate!).

Progress Report 61

It has been quite an eventful summer - not least because the weather has been very changeable which is not good news for garden railway modelling. However, there have been a few developments since the last Progress Report (see Progress Report 60).

• In terms of infrastructure, the major development has been the completion  (after two years) of the viaduct crossing the access to the patio. In addition, the unintended incline at the end of the swing bridge on the approach to Bulkeley station has been iron-out.
• Very little has happened with the permanent way, though the siding for the cattle dock at Beeston Market has been extended a little.
• A very pleasing development has occurred in the motive power department - the last remaining track-powered locomotive (Fowler No.7 - Tollemache) has been converted to battery power
• There have been several developments in Controls - some of the Deltang receiver/controllers have been updated in the locos and a new Tx20 Deltang transmitter has been constructed to now give three separate controllers for locomotives
• Some of the little-used rolling stock has been passed on to other railway companies and there have been a number of general repairs to serving rolling stock
• Operating sessions have been sporadic - partly owing to the unpredictable weather, partly because we have been away on holiday and partly because other developments have taken priority. However, I have managed a couple of full operating sessions and played host to fellow modeller.

Infrastructure

Two years ago, I decided to replace the rather ramshackle structure which pretended to be a viaduct across the access path to the patio. This had become an experimental test-bed for construction techniques with the plywood base being covered at various times with a range of claddings such as tile cement, plaster of Paris, grout and filler. The intention was to indent and/or scribe these materials to represent stone blockwork. None had proved particularly successful and the plywood was beginning to rot.

 As the viaduct needed to be readily removable to allow access, I wanted something relatively lightweight but nonetheless reasonably realistic. I had already built structures using balsa wood to represent stonework (following ideas proposed by Peter and Kes Jones in Making Model Buildings for Garden Railways). And so a lightweight plywood substructure was made and clad in around 3500 individually cut, shaped, glued, grouted, textured and painted balsa wood blocks.

 

On a less ambitious scale, there had always been a slight drop at the end of the swing bridge at Bulkeley but I had begun to notice that the slope was becoming more severe. The trackbed at Bulkeley seemed to have dropped by around 5cm.

Previously, I had attacked the slot into which the end of the bridge fitted with a hammer and cold chisel, but this time I felt the time had come for more drastic action. The slot was deepened with an angle grinder.

The transition from bridge to terra firma is now a lot less abrupt - but as you can see, the ground level has shifted quite considerably over the past ten years.

Permanent Way

Apart from the usual ongoing maintenance of keeping the stock moving and the wheels on the track, there have been no major developments on the permanent way since the last progress report. The most significant development has then the extension of the siding serving the cattle dock at Beeston Market. When I built the cattle dock (see How I constructed a cattle dock), I was more concerned with ensuring that the dimensions of the gates and railings matched the positions of the doors on the four cattle wagons which the line possessed at that time.

What I hadn't appreciated was that the overall length of the siding would not accommodate the fifth ( Accucraft Welshpool & Llanfair) cattle wagon which the line acquired. Fortunately, there was sufficient space between the end of the siding and the adjacent tracks for it to be extended by 3cm. However, the track had been embedded in concrete and so I was unsure as to whether it would be possible to extend the siding without major engineering works. I decided that, if I could sever the track just before the rail built buffer stop, I might be able to insert a short length of track with the minimum of disruption.

The track was cut with a slitting disk attached to a mini drill and the buffer stop was prised out with a hammer and chisel. The 3cm length of track was inserted into the gap.

The siding is now just the right length to accommodate all five cattle trucks, with plenty of room for stock to pass by.

Motive Power

The biggest development here has been the conversion of my last track powered locomotive to battery power. The Fowler(ish) Loco No. 7, Tollemache, was the first loco I scratchbuilt and so has particular poignancy for me (see How I constructed an early Fowler diesel locomotive).

During the build, I had had a major problem with the layshaft. The only flycranks I could find (from Garden Railway Specialists - GRS), had 8mm offsets but the cranks on Tollemache's drivers had 10mm offsets. Although I solved the problem at the time by slotting the bearings in the connecting rods, I was never happy with the sloppy motion which this produced. I felt I needed to find a better way of solving the problem before I set about making the conversion to battery power. It turned out that the solution was a lot more straightforward than I had anticipated (see How I increased the offset on my GRS whitemetal flycranks)

Once this problem had been sorted out, the installation of the three 18650 li-ion batteries, protection board, switch, charge socket and the Deltang Rx65a receiver/controller was very straightforward (see How I converted my Fowler diesel to battery radio control).

She has now assumed duties and has already participated in a couple of test runs. I can't wait for some decent weather so she can once more take part in a full operating session. As you can see, I am now more than happy to video her running slowly.

Controls

There have been a few developments in the area of control technology on the railway. The most significant is the construction of a new Deltang transmitter, a Tx20 (see How I constructed a Deltang Tx20 transmitter).

As indicated above, Fowler Loco No, 7 (Tollemache) has now been converted from track power to battery power using the Deltang Rx60a receiver which was removed from Manning Wardle Loco No. 6 (Harthill).

I had re-bound this loco from my Tx22 transmitter to my Tx21 transmitter but was finding that the Tx22-enabled Rx65a was struggling to remain bound to the Tx21. Rather than re-program the Rx60a, I decided to buy another Rx65b which was already programmed for use with Tx21 (or Tx20) - an Rx65-2. 

When I constructed an IP Engineering 'Jessie' kit which became loco No. 8 (Wynford), the only suitable Deltang receivers which were available could handle only 1.5amps.  

Wynford sometimes drew more amps than this and so was unreliable with the lower power receivers. To solve the problem I installed a Deltang Rx102 receiver linked to a Brian Jones Mac5 ESC. Since the release of the Deltang Rx65, I have been meaning to install one in Wynford but, as she was functioning happily, I felt there was no urgency. An enquiry on the 16mm NGM forum from a fellow modeller, asking which Deltang Rx would be most suitable for an IP Engineering 'Jessie' with a soundcard, prompted me to replace the Rx102/Mac5 arrangement with an Rx65, to ensure my suggestion was appropriate. The Rx65 needed to be re-programmed to allow the DigiSounds soundcard to be controlled from the transmitter and  Wynford is now happily re-energised and back in service (see How I installed an Rx65 in my IP Engineering 'Jessie').

Manning Wardle Loco No. 4 (Bulkeley) has now had her Deltang Rx60 receiver replaced with an Rx65. Although Bulkeley was working satisfactorily, I have decided that I want to standardise the receivers in my locos and the Rx65 includes features which one day I might want to exploit (eg auto-station stop).

Rolling Stock

Because I have recently constructed a new gunpowder van (see How I constructed a gunpowder van), the Swift Sixteen corrugated van which had been pressed into service as an explosives van was now redundant and so was sold to a fellow modeller through eBay.

Similarly, the Accucraft Lynton & Barnstaple van which I had bought a few years ago was now surplus to requirements. The other vans on the line (converted from LGB vans) are larger and hence L&B van looked out of place. It too followed the corrugated van.

Apart from some ongoing maintenance (mainly re-fixing couplings) there have been no further developments with rolling stock since the previous Progress Report.

Operations

I have had the opportunity for a few operating sessions since the last report in July, though these have been less frequent than I would have liked as holidays, the weather and projects (such as the viaduct) have taken up time that might have been used for running trains. However, a couple of full operating sessions have been squeezed in and from time to time I have run a train or two for an hour or so.

Having constructed a second rake of coaches (see How I converted Bachmann Jackson Sharps into Leek & Manifold coaches), I felt it was about time I ran two passenger trains at the same time (assuming it was a busy market day during the summer season). Here we see Sharp Stewart Loco No. 5 (Tarporley) on an Up passenger .........

...... crossing Manning Wardle Loco No 6 (Harthill) at Bulkeley on a Down passenger service.

During another operating session, a few photos were taken of trains in action ....

Barclay Loco No. 2 Beeston about to depart Beeston Market

Freelance diesel, Wynford, passing the engine shed at Beeston Market

No. 2 (Beeston) passing an Up ore train at Bulkeley

Peckett Loco No. 1 on a Down pickup goods passing an Up ore train at Beeston Castle

No. 1 on an Up goods approaching Bulkeley while No. 2 approaches Beeston Castle on a Down passenger

In addition, the railway hosted a visitor, Derek, who brought two locos with him - a Peckett and a Hunslet built from GRS kits

Derek's Peckett leaving Peckforton, crossing the viaduct

Approaching Bulkeley on Gallantry Bank

Peckett and Hunslet (Linda) storming up Gallantry Bank

Double header approaching Bulkeley

Autumn is upon us. As you can see from the above photo, the apple tree is starting to shed its leaves and there is a definite nip in the air. My railway todo list seems as long as ever and so, over the winter season, I hope to clear some items off it, such as:

• installing interiors and lighting in the Leek & Manifold coaches
• installing solar lighting at the stations
• adding more detail to goods wagons
• exploring auto station stop for locos equipped with Rx65b receivers
• constructing a couple of horse drawn wagons
• constructing buildings for the approach to Beeston Market station
• etc etc etc

As I said in one of my first blog posts made in 2006, I doubt my railway will ever be finished.