Welcome to the Cumbria & Scottish Borders Area Group Forum

 An Excellent presentation today at the West of Scotland Area Group today where Chic and Jim share their experiences of using CNC machines for different uses. Covering both laser and spindle based equipment, it was amazing to see the flexibility of these machines for making PCB's , cutting card models and engraving wood and perspex. The session was recorded and will hopefully appear on the WOSAG website soon. Suitable software for creating design files was also discussed.  These included DesignSpark, FreeCAD and Eagle. For drawing, the Open Source InkScape software was highly recommended. Having just started using this particular software a few weeks ago myself, I can support the recommendation. I had no idea however, of the range of extensions available for this free software. One included a .grbl  output ( pronounced Gerbil in the UK)  that would translate your drawings into the machine code file required for these CNC machines. Chic showed a few circuit boards he ...

 Davy Dick's  PMP 5 Logic probe is a really useful piece of testing gear to establish the logic output of a 5 Volt circuit.  The original kit is built on stripboard and requires three tracks to be cut which can be problematic for some. It may be useful, particularly at exhibitions, to show the status of a digital signal being output from one PMP Kit to ascertain how the next circuit should respond.  A good example of this would be PMP4a (Shuttle Add on) driving PMP 18 (Ezy-Points). To avoid any confusion of polarity, I arranged for the Power and Logic headers to be made available at both ends of the circuit and colour coded them as follows. Red  + 5Volts  ;   Black 0 Volts common ground  ; White  - Logical Output to be tested All the tracks in my version are continuous and will fit on the same board provided in the kit. Obviously, the component layout have been changed slightly but still follows the original circuit diagram. A common str...

 Following on from the station lights blog I published awhile ago I have now have the lights coming on automatic when a train comes into any of the four tracks using a Arduino Nano As I have some spare Ezybus boards I used one of these to do all my connections to the Nano, it also has a 12 Volt input to power the Nano As my layout is DCC I am using a MERG PMP7 for train detecting, which uses a opto-isolator, to control the LED on the control panel. One side has a voltage on, in my case 5 Volts with a dropper resistor which brings it down to about 3.5 Volts, the other side is connected to ground 0 Volts. One of the Nano pins reads this voltage, if it is 3.5 volts it does nothing but if it at 0 volts it switches on another pin on the Nano. I have used 4 PMP7's for the 4 tracks and used 4 pins on the Nano ( one for each track ) if any of the pins goes to 0 Volts it will switch on the output pin, this in turn switches on a replay to power the LED's ( I have not used the output pin ...

 Today's West of Scotland talk was on Solenoids. Soenoids are still extensively on some model railway layouts. H&M, Peco and SEEP are common manufactures. Some early controllers have a 15v ac supply which can be used to operate the solenoid. Push buttons or passing contact switches are normally used to operate solenoids due to the large  operating currents involved. These passing switches are expensive at around £9 to £16 for every single point. With the voltage drop across the solenoid a higher voltage is sometimes used supplied by a Capacitor Discharge Unit (CDU) The circuit of  a typical Gaugemaster CDU was discussed costing around £15.  Davy then showed us an equivalent Veroboard version for around 71p that would work with a centre off SPDT switch.  The MERG dual CDU version using a simple on/off switch uses a circuit that operates the solenoid and charges the opposite direction capacitor at the same time. If this unit is placed near the point only a sin...

 On Sunday Davy Dick ran an online version of his Electronics 2 course. Normally he runs them at his home with around six or seven attendees which gives plenty time for questions and the opportunity to see and touch the circuits The course was divided into three sections covering Numbering systems - decimal, binary, hex - how do we use them in our projects Digital signals • How do we store numbers (e.g. inside a DCC decoder or inside the Servo4 module) • How do we pass numbers (e.g. from a command station to a loco, CBUS, etc.) Serial / parallel connections How transistors work  Using transistors as switches and operating high power devices. Integrated Circuits Examples of ICs, PICs Demonstrations of popular ICs. • Driving a 7-segment display • LED chasers • Route selection • Power drivers, including motors • Comparators (DCC TOTI) 555 timers - and how they are used in Pocket Money Kits How this very popular (and cheap) IC works and its three operating modes: • Bistable – as i...

 A really interesting project was discussed at tonight's JALSIG Zoom meeting. The Basic shuttle kit PMP4 was designed in February 2013 and remains one of the most popular Pocket Money Kits. It uses a 555 circuit as a basic timer  and changes the state of a relay to reverse the polarity of the track. Davy Dick has revisited this circuit but this time used a 14 Pin PIC (16F676) to replicate the circuit and  add a few enhancements to take advantage of the additional pins available. It is hoped that this will eventually appear as a Pocket Money Kit with PCB sometime in the New Year. Potential features include adjustable cycle times, controlling semaphore or lights using a delay or detectors set by an option jumper and incorporation of PMP4a  for shuttles with branches.   Two additional pins might be used to control crossing gates or trigger sound effects or anything else your imagination fancies. Using around 12 components and some simple coding techniques, thi...

 Thirteen members joined us on today's Cumbria Zoom meeting where Tony Hoath demonstrated and explained his Arduino based shuttle layout which he uses for bedding in new OO scale locos. The basic Pocket Money  shuttle Kit suffers from the sudden stop when the track break is detected and the sudden start when the relay is reversed. The affect can be minimised if slow speed is selected. Tony uses a simple Light Dependent Resistor to detect the presence of a loco and then gradually decelerates and finally stops on reaching a second sensor. The circuit is shown below. As the relay is only switched when no power is being supplied to the track, a much smaller relay can be used to change direction. As the locomotive returns it ramps up to a set speed so the rather unrealistic stop / start is avoided. Tony's sketch is available below. //00 test track //1 loco to run back and forth //2 LDR,s to determine train postion. //2 push buttons. Green starts and stops operation. The sto...

 At this mornings Virtual Area Group Meeting, Rob Thomas described how he uses  CBUS to control his OO9 layout.  He discussed the Pros and Cons of the various available systems including MERG's Automatic Train Controller, commercial offerings and Mike Bolton's Basin Speed Controller. Having opted for the Basin Speed Controller version as the basis of his project, he then looked at how he might add additional control using CBUS. Various versions were developed starting with a seven speed and stop initial project with subsequent modifications to overcome some of the problems associated with the different behaviours of individual train motors. Speed and Inertia were eventually  controlled using files created from a Python script and stored on an Arduino. He uses RFID to identify the locos so that the correct profile can be loaded to the controller. This is certainly not a beginners subject but the video is available on the Merg website for those interested.

 Yet another well attended meeting of the West of Scotland Group with 34 members attending including Greg from Australia. Davy Dick showed us some work he had been doing on improving the basic Track Circuit Voltage detector (PMP 1). A commercial offering shown below has recently been reduced to just under £13 pounds. The theory behind how these work was explained and various potential methods outlined including rectification for DCC users. Keith Shovelin also demonstrated a DCC version that included a voltage display which would be ideal for fault finding on a layout. These solutions are all substantially cheaper. George showed us his new Diorama of a street scene with flashing road cones using pre-wired  MicroLitz leds with  a welder repairing pipes using basic PMP kits and some 3D printing. Davy then discussed progress on the carriage lighting project using the much smaller SMD ITR8307 instead of the TCRT5000.  He demonstrated the voltage change using a flag attach...

 At the 23rd October Meeting of the Cumbria Area Group, we were joined again by David Roberts to present the second of his talks on Power Supplies, this time covering Voltage Regulators for Electronics Modules. He covered linear regulators including the 78xx and 79xx series.  The important subject of regulator efficiency was discussed with the requirement of heatsinks to dissipate the unused energy. How Power Supplies are designed and used was illustrated using some of the readily available MERG Kits including the 5 Volt Adaptor Module (Kit 60),  12 V from an ac supply PMP 6 ( Kit 806), the Universal PSU (Kit 920) and finally CANACC5 (Kit 85). Then the much more efficient and more expensive switching regulators were covered towards the end of the talk, followed by a general question and answer session. Andy Woolass has managed to record both of David's talks and I am delighted to let you know that these are now available on Channel 36 in the MERG TV section of the website...

 The North Wales Group are currently running a project on Shuttle boards. This is an ideal project for those new to the hobby and is based on Davy Dick's Pocket Money Kits. Allan Geekie is assisting on the project which benefits from the availability of Printed Circuit Boards rather than the normal stripboard. Full details are available on the North Wales shuttle blog , but you will need to be  a member of the Group to access the pages. Apart from the outlay on the PMP kits, Allan has produced a set of additional parts that include the PCB's, additional components and a 3D printed frame with inserts to assist with mounting. As you can see from the photograph above, the Kits being used are:          PMP 10  Speed Controller          PMP 4    Simple Shuttle         PMP 15  Station Auto Stop There is no reason why this cannot be extended further using PMP4a  - Shuttle Add on which works...

At today's West of Scotland Area Group meeting, we were treated to a presentation and demonstration by Chris Cosgrove from the East of Scotland Area Group. Their layout is a basic oval with two additional loop sidings. A further siding leads to a turntable off which is a track to an engine shed. To add interest, a working level crossing with flashing lights will be added. The layout is controlled using an EzyBus controller, one input board and two output boards all connected by I2C.  The level crossing is triggered by two laser TOTI's (one each side). To create the necessary delays, Chris designed a circuit using the PIC 12F675, the outputs of which are fed to the EzyBus Input Board. Switches are also connected to the Input Board for point selection, Engine shed door operation and turntable position selection. The Output boards are used for Servo Control of the points, the automation of the Engine Shed doors and for the level crossing gates. Additional digital outputs control t...

The JAL Special Interest Group has a meeting on Monday 14th September at 19:30     These are sessions that are open to all members, both in the UK and internationally. It normally discusses programming PIC chips using the JAL programming language.  Davy Dick from the West of Scotland Area Group will be the guest speaker and will be discussing how he goes about starting a program from scratch, using his automated canal barge and the traffic lights Pocket Money Project as examples.  As this session covers programming technique, it is also useful for Arduino and other platform  programmers.  If you have not yet signed up to JALSIG then you will have to   update your profile

 At today's Scottish Border Area Group Zoom meeting we had about seven attendees. As it was a coffee and chat meeting various subjects were discussed, including carriage lighting. Keith showed us an alternative method involving conventional led strips, four button cell batteries and the lights being switched on and off using a reed switch in the presence of a magnet. Details of the circuit will be made available later. For those interested in learning how to program and use Arduino's on your layout, Derek showed us a really useful kit that includes an Arduino Uno, breadboard, jumpers and USB and power cables. In addition there are a number of experimental parts that include a servo motor and driver, leds, switches and various sensors and display types/ All parts of the kit are contained in a convenient plastic case. This kit is available on Ebay for around £20 and is an ideal starter kit.

 Sunday's Scottish Border Zoom Meeting featured a talk by John Gowers on Control Panels.  Twenty one members joined from around the country with our normal group numbers swelling to over fifty as a result of Covid-19 and the adoption of Zoom meetings. John started his talk with how he used to do things with switch panels and complex wiring before turning to JMRI (Java Model Railroad Interface) an open source project that consists of JMRI, DecoderPro and PanelPro. These programs are available as a free single download from JMRI He predominately uses CBUS modules to transfer signals across the layout and they have designed their own PCB's to ensure switches and lights exactly match the laser etched front panel. This is made of a two colour layered acrylic sheet with the top black layer being etched away to reveal the white tracks underneath, Holes are drilled through to accommodate the push button led switches mounted on the PCB below. Some custom CBUS kits have been made by the...

 Another very well attended Zoom meeting with 34 participants. Davy showed us the commercially available automatic train stopping unit available at £12.53 from Brimar and compared it with the almost identical PMP 15 kit from the MERG Kitlocker at  only £2.65.  With these kind of savings, MERG membership is worth every penny. Chic Thomson treated us to a very entertaining presentation on simulation software for Electronics. INKSCAPE  is a free open  source drawing package. There are many Arduino Simulators available but Arduino Simulator 1.5.1 is an excellent open source offering.  For those interested in PICs simulators are available within the JAL compiler (Just Another Language) and MPLAB Sim is available within MPLAB but seldom advertised. Electronics Workshop 5.1 is a program no longer being developed but a useful tool for investigating any electrical or electronic circuit. Apparently you can Google it but there are a few insecure sites so be careful. F...

Another excellent Zoom Meeting this afternoon run by the West of Scotland Area Group. Over forty people joined the meeting. Davy Dick first showed us a  commercially available multi function stepper motor driver module. Operating between 5 and 12 Volts it works on both four and five wire motors. Four different operating modes are available selected by jumper. There are two push button switches on the board that have different effects depending on the selected mode. These switches could be removed and replaced by external ones.  In addition a 4pin header allows further  connection to switches or sensors. The large pot controls the speed of the motor and the smaller one, the length of travel when that mode has been selected.  This is a good board for simple end to end travel ( shuttles) and costs less than £5 on eBay (other suppliers are available).  Davy demonstrated it working driving a NEMA-17 motor with  lead-screw and limit switches and then with the muc...