Steve Hewitt

Today has been a special day for Lime Street Station.... John and Pauline hosted a barbecue for the builders of the layout's "home shed" and their neighbours who've had to tolerate lots of minor inconveniences during the past six months or more whilst the building has been constructed. The"Builders" received a great round of applause when they handed over the keys to John, and John and Pauline then cut the ribbon on the door. (note the address) A few members of the operating team were on hand to demonstrate the layout to the visitors. John had even managed to lay on the Red Arrows. (They flew past an their way to the Southport Air Show.) Inside, John described the present state of his project, which is in its third incarnation over a period of more than twenty-five years. The next week or two will see some fairly intensive work on the layout's operation. We hope to improve the sequence of operations to eliminate undue delays in the movement of traffic in what was quite a busy terminus. Technical developments will see progress on the station roof and the signal control system before the layout will be partially dismantled to allow the scenics to be progressed. Progress reports on these will be made as and when we have the opportunity..... Steve.

I believe I've mentioned previously that all the semaphore signals on Lime Street are to be operated by servo motors. The controllers for these are being developed by Geoff Peters, who is responsible for all the wizzy computer stuff in the control system for Lime Street. The signal controllers will be fully integrated into the route setting system, to ensure efficient operation with minimum delays. The controllers for Lime Street will be able to look after some eight servos each, but the exciting news is that a "two servo" version is being developed in parallel which will go on general sale in the not too distant future. I brought an early example home with me to try out. I'll start a new topic to report on it as soon as I can. I can tell you now it has some very good features to ensure easy installation and setting "out of the box". Steve.

Here are one or two to be going on with: Rob refreshing his memory with John before we started running. He'd not seen the layout since Manchester last year. Brian deep in thought? The first working lunch. We'll never find the damned screw. The first to go missing since moving in! No doubt more, with a bit more layout content will appear in due course. Steve.

The "not too distant future" came today. In the meantime I've been away on holiday for several weeks, but the time has been used to excellent effect by John and Brian. The layout is in a new, permanent, custom built home (more details sometime) and the greatest care has been taken in its assembly. (Previously, the layout has only been assembled in rented industrial units and at exhibitions, which has always imposed time pressures) The laser levelling technique we use has been modified slightly to ensure true level assembly over all the length and depth of the layput. Known faults in the layout from previous outings have been rectified. Again something not always possible with the majority of the layout in storage most of the time. The result shows! John, Brian, Rob and I have had our first team operating session since the Manchester show last autumn. We got through a full operating schedule with almost no "hand of God" incidents. I overran a section break once, and a point blade failed to close fully on one occasion. A re-wheeled loco presented a short between wheel and pony truck, and a slight binding on three frogs. These have been logged for attention, and the remedial action will subsequently be entered into the log book. With access to the layout readily available, we all expect progress on the many sub-projects to be rapid. We'll try to keep you up-to-date on this Topic Steve.

Quick progress report: Today, John, Brian and I brought the layout home from storage where its been for several months. Looking forward to getting my hands on the controls in the not too distant future. Steve.

I've recently completed a 7mm scale Home and Distant signal which uses servo motors and Embedded Controls units very effectively. Here are a couple videos which show the results. The servos in action. The resulting movement of the arms. If the Distant is pulled off first, the arms don't move until the Home is also cleared: You can see the Distant arm tries to move when it is pulled off, but is prevented by the mechanical slotting, as in the prototype. Steve.

Hi, The demo is to show alternative switch types all doing the same sort of thing. The switch on the left is a "centre off" switch, with a centre bias. i.e. it springs back the "off" when released. Pull the lever towards you and release, moves the servo to the "clear" position. Push the lever away and release, moves the signal back to "danger". The push buttons in the middle work as you'd expect. Press and release the green button, the servo moves to the "clear" position. Press and release the red button, the servo moves back to "danger". The switch on the right is an old H&M "Flash" switch. Pull the switch, (quite slowly) and the servo moves to "clear". Push the switch, (again quite slowly) and the servo moves back to "danger". If you move this switch too quickly the contact is too brief to be recognised by the controller. They are just alternative ways of giving the "momentary" switch contact required by the Switch Pilot Servo. regards, Steve.

I’ve started this topic in order to answer questions arising in mikemeg’s superb thread “More Signals at Hessle Haven & Scarboroughâ€. I’ve been using servos to drive semaphore signals since seeing a demonstration on the Embedded Controls trade stand at a Wignal exhibition in the late 1990’s. In fact I was so impressed with what I saw that I volunteered to build the signals for our club’s “Oxenholme†layout. This was my first excursion into signal building. Subsequently our club – Blackburn & East Lancs MRS – adopted the same techniqes for all semaphore signals on club layouts. I’ve now built operating signals for our layouts in 2mm, 4mm and 7mm scales. Currently I’m building the signals for John Holden’s model of Liverpool Lime Street, which are also servo driven, but with bespoke controllers. Before I go any further, let’s get one thing straight – I know almost nothing about electronics. Fortunately, I know a man who does! The first question I’ve been asked is “which servosâ€. Originally, I used the servos which came in the package with the Embedded Controls controllers. These are quite substantial, with the following typical characteristics. Dimensions (mm): 19.0 x 38.0 x 34.5 Weight (grams): 45.0 Speed (sec): 0.25 Torque (Kg.cm): 3.10 Ball Raced: No They will definitely pull the skin off a rice pudding! More recently, I’ve been buying controllers without the servos, and using the following. These are what I’d call medium sized, with typical characteristics: Dimensions (mm): 11.5 x 24.0 x 23.0 Weight (grams): 7.5 Speed (sec): 0.12 Torque (Kg.cm): 1.17 Ball Raced: No This model is the SuperTec JP EN ER G Super Micro Digi 7.5g The “Digi†refers to digital, and is reputed to give finer resolution of movement. The smallest servos I’ve used are the SuperTec JP EN ER G Super Micro Servo 7.5g which has the following characteristics: Dimensions (mm): 8.0 x 20.0 x 19.5 Weight (grams): 4.7 Speed (sec): 0.12 Torque (Kg.cm): 0.60 Ball Raced: No Prices from £5 to £8 approx, plus postage etc. I have bought all my servos recently from http://www.servoshop.co.uk/index.php No relationship other than a satisfied customer. I know some have bought much cheaper servos direct from the Far East on eBay. However, the ones I have seen have lacked build quality. They are a bit “sloppy†where the shaft is mounted. What we used to call “headache†when I was an apprentice. This leads to a loss of precision in signal movement. You don’t need to spend a lot on high performance, ball bearings etc. for our application, but avoid the cheapest – you get what you pay for. As a rule, I try to use the SuperTec JP EN ER G Super Micro Servo 7.5g wherever possible. It is very smooth runner and seems to do the job very well. The smaller 4.4g models are useful where space is limited : This twelve arm gantry is a case in point: What about servo controllers? I started using the Embedded Controls controller, and still do so today wherever I can. Unfortunately, it isn’t currently commercially available! I’m hoping that this will change in the fairly near future. This gives a really good movement to your signal arm: Slow pull to “Clearâ€; Slight return to at the end of the movement where the signalman has released the lever; Slight move of the arm as the signalman pulls on the lever to release it’s lock; Quicker return to Danger with a couple of small bounces at the end. All that is seen at the servo quite easily! Whether the signal arm shows the same depends on how well you build your signals. Any slop or tightness in the operating linkages and the finesse is lost. Just two adjusters - one for the Danger position, and one for the Clear. If the Embedded Controls controller were available, it would probably be in excess of £15.00 each from the usual suppliers. One unit required for each arm (servo motor) you want to drive. I’ve experimented with the MERG “servo4†controller. This is available from the Model Electronic Railways Group - MERG – an Internet group. To members only. I joined for a couple of years to buy one or two of their kits, which are excellent quality and value. Not really understanding electronics, I didn’t get any other benefit from membership, and let it lapse. This easy to build kit will control up to four servos independently. The motion is much simpler. Danger to Clear at one speed, Clear to Danger at same or another speed. The end positions and the speeds for each servo are set independently. This can be done by using free software, download to your PC from the MERG website. Alternatively you can buy and build the MERG servo setting box kit. Either your PC or the setting box plugs into the 9-pin “D†socket seen in the picture. For a PC You will need a USB to Serial cable. The third servo controller I have knowledge of is the “ESU switch Pilot servoâ€. This is a dual DCC/analogue controller, which I have used on my demo. stand as an analogue device. (I know not much about DCC). It again will control up to four servo motors. The motion control is even more basic. Each servo can have its end positions set. The speed of movement can also be set, but it is the same in each direction per servo. This controller is more suited to point control than signals. Besides the motion control, the control principle is akin to a solenoid point motor, i.e. a passing contact or momentary switch is used. The controller will also only allow one servo to operate at any one time, so it isn’t suitable for simulating a “slotted†signal, where you may or may not want two arms to move simultaneously. The unit on my demo stand was kindly donated for evaluation purposes by “South West Digital†I know there are other servo controllers available, but I do not have first hand knowledge of them. In one case not for the want of trying! If you wish to see these demo items for real, I’ll be at the ALSRM’s Bolton event on February 26th, and at Warley again in November. I look forward to your further questions……….. Steve Hewitt.