Fullscreen HTML5Med Res (??MB)HTML4

Part 1: introduction and overview T Machine Have you ever wanted to build your own pinball machine with a custom layout, artwork, sounds and lighting? It might seem like a daunting project, combining electronics, mechanics and software. In this series, we show how to design and build every part at home, from scratch! his major project, presented over the next few issues, will provide you with all the pieces to make your own pinball machine. You can pick and choose all aspects of it and ‘roll your own’ by 3D printing. Not only does that make it incredibly customisable, it avoids the expense of buying commercial pinball machine parts. They can add up fast! It seems like just a few months ago that I was talking with our most esteemed editor and asked what he thought a fun project would be. His answer was somewhat unexpected: a pinball machine. My immediate response was, “Sure, why not. I always wanted to build one of those as a kid.” I should have reflected on the reasons why I never went ahead with that before. In retrospect, that was a bit of a “... hold my beer” moment! The technology in a pinball machine is not advanced, but it is definitely in the complex electromechanical world. There are some very substantial forces involved in many of the mechanisms on a pinball deck, and controlling them reliably is not easy. There is a lot of electrical sensing and control, and therefore (in old-school machines, at least), a lot of wiring. Make no mistake, if you decide to follow my lead, you will be embarking on a major project, and there will be a lot of work. However, nothing about it is really difficult, especially since we have already done much of the hard work. We will be presenting triedand-tested electronic and mechanical designs. Critically, you will be able to download some files and start printing tested and verified 3D parts immediately. While the PCB and wiring are superficially impressive, the majority of the effort in this project has gone into realising a DIY-friendly approach to making the critical kickers, flippers, targets and bumpers. Of course, it is possible to buy parts to make a pinball machine; however, they are excruciatingly expensive. Also, many of the parts on the market are second-hand, which introduces reliability concerns. So what we did was draw on some experience and skills in 3D printing to bring more of a DIY approach to this project. That keeps costs down, as does using a Raspberry Pi Pico 2 microcontroller module as the ‘brains’ of the system. Australia's electronics magazine siliconchip.com.au Phil Prosser’s Phenomenal Pinball 26 Silicon Chip This also means that should anything break in the future, it will be easy to repair. Simply print a replacement part, swap it in, and away you go! We could even see Silicon Chip readers making and sharing their own elements to enhance this new ‘pinball ecosystem’. Don’t get the impression that following my instructions will completely remove the need for mechanical skills. Still, you will be making parts that we (and you) know will work when assembled and wired correctly. We spent a lot of time simplifying the wiring, with ribbon cables for most of the lights and sensors, and a control board that is ‘plug and play’. This was an attempt to keep the inevitable spaghetti wiring manageable! We will present all the component parts required for a decent pinball machine, including: Flippers Bumpers (that kick radially) Kickers (that kick outwards) Targets Rollovers (which detect the ball passing over) Loader and ball release A range of lighting parts A scoreboard A control system and a power supply You will be able to use some or all of the parts we used. You may decide to make more or fewer of some of them, or make your machine larger or smaller than ours. Before deciding if you’re going to build your own pinball machine, you will probably want to see what ours looks like and how it is to play. To that end, in addition to the photos in this and the following articles, we also have several gameplay videos you can view at the following link: siliconchip. com.au/Video/Pinball1 The controller includes more self-testing functions than we would normally include, allowing you to use a computer to monitor the state of the machine and test every component. So, we have some pretty solid built-in help for debugging. In a complex system like this, you want to be confident that you can track down any problems that arise. In addition to electronic and electromechanical parts, we will also provide several 3D-printable deck sections, especially around the reloader and ball release, which we think is pretty 📍 📍 📍 📍 📍 📍 📍 📍 📍 siliconchip.com.au cool. You don’t have to use these if you don’t want to; you may prefer to do some woodworking instead, or flex some of your other skills. The controller won’t care. So, you can make a deck that suits your needs; you don’t need to copy ours (but you certainly can if you want to!). We have included all the Fusion 360 CAD files in our download section, so if you want to modify these parts, you can do so. This software is free for non-commercial (hobbyist) use. The defining aspects of a pinball machine include a spring-launch mechanism and a playfield with obstacles and targets. Hitting the targets increases your score. The game ends when the ball goes into the ‘gutter’ a few times (usually three). Variants of the pinball game with these features have been around since the 1700s. In the 1900s, more complexity was added, including flippers and a coin operation mechanism, allowing pinball to become a commercial game. Post-WWII (the early 1950s) saw the widespread introduction of electrification and automated flippers, with the familiar placement of flippers near the bottom of the deck, allowing longer play and better control of the ball. Through to the mid1970s, all pinball machines remained electromechanical devices utilising relays for control and capturing scoring. In the mid-1970s, microprocessors were introduced, which enabled much more complex lights, sounds, scores and other functions. My rash promise to the editor was to bring the essence of this very long history of the game together into a project that you can make yourself. As implied above, you will be able to ‘mix and match’ and even customise our part designs into your own creation. As a final comment, this collection of the controller, electromechanical parts, example deck and software will do a lot of your heavy lifting. Even so, building a machine is a substantial undertaking. Keeping an oldschool pinball machine operational is a very technical job, and building one from scratch inevitably has some tricky parts. Photo 1: the general layout of the Pinball Machine. It’s highly configurable; you don’t need to do everything the same as us. You could have more or fewer bumpers, kickers, LEDs and so on. It’s designed to be flexible, to suit your idea of how a pinball game should work. June 2026  27 Fig.1: the system block diagram. Inputs are shown with red lines and outputs with blue. All inputs are active-low inputs, some from open-collector inductive sensors and some from pushbutton switches and microswitches. The outputs are direct drive for the 7-segment displays, opencollector outputs for the LEDs and open-drain Mosfet outputs for the high-power devices. For those of you with an artistic bent (or who know people with such skills), this will be an opportunity to let your creativity loose. We have made basic decorations for our machine, but we are sure that you, the reader, will come up with something even more unique! For those with a software background, we are also providing the full Visual Studio code, so you can hack into it and change the logic, tunes, sound effects, light sequences and whatever else you want. The world is your oyster. Let’s start with the system block diagram, shown in Fig.1. The central Control Board is a hefty 246.5 × 240.5mm, loaded full of through-hole parts. None of these are remotely fancy; the Raspberry Pi Pico 2 is the only high-tech part. This board has inputs for all buttons and sensors, LED drivers for the displays (a mix of 7-segment displays and individual LEDs), 12 Mosfet outputs that can drive very heavy loads, and interfaces for inductive proximity sensors. For the LEDs, the 7-­segment displays are driven directly by 74HC595 serial-to-parallel registers, while individual LEDs have bipolar transistor buffers to handle higher currents. 28 Silicon Chip All the inputs and LED connections are via 10-way ribbon cables, which run to small breakout boards local to where the LEDs and inputs are (see Photo 2). This simplifies the wiring considerably, as you can crimp a 10-way IDC ribbon connector in seconds using a vise or (ideally) a dedicated crimping tool. All power outputs are via pluggable headers using figure-8 cables. We used cheap speaker cable. This all operates at 24V DC and up to 6A, so we can’t use lightweight connectors. We recommend pluggable screw terminals, which again are quick and easy to assemble. If you are tempted to solder these wires to the board, have a bit of a think about servicing this machine later. Australia's electronics magazine We found the best arrangement was to have the power supply and controller behind the main display, with ribbon cables and high-current cables running from there to breakout boards at your sensors and effectors – see Photo 2. The Control Board is busy, as you can see from Photo b1 overleaf. Top deck We 3D printed the entirety of the top deck. We did this because we could dream up a rather complex layout, print it, try it, then tweak it so the game played better. The flippers can drive the ball in a range of angles, for example we wanted to have interesting things happen fairly often, so we moved the bridge entry to the left of siliconchip.com.au 3D-printed Electromechanical Parts Here’s an overview of the critical parts of the pinball machine that can be 3D-printed using files you can download from our website. In addition to the printed parts, some standard hardware is used (screws, nuts, washers etc) plus, depending on the part, pre-made switches, solenoids and other bits and pieces. 1. Flippers (Photo a1) – these are the way the user interfaces with the ball. They’re positioned near the bottom of the machine and pivot upwards when the user presses a button. If timed correctly, they will fling the ball up as it passes near them into the location desired by the user. If timed incorrectly, the ball may go somewhere you don’t want it – including in the gutter at the bottom, ending your turn. They use two solenoids to give enough speed and power to kick the ball properly. Photo a1: one flipper; a pair of these are what the player uses to move the balls around the deck and (hopefully) score points while avoiding the ball falling down the bottom, ending their turn. Note that this flipper is missing its rubber band. 2. Bumpers (Photo a2) – these are circular objects on the deck that detect when the ball hits them and push it away rapidly (driven by a solenoid). They make noise, flash lights and cause the ball to ping around rapidly, making the game much more exciting. 3. Kickers (Photo a3) – these are positioned touching a flexible band. If the ball hits the band, that is detected by a switch and the kicker then pushes the band out, causing the ball to fly away. They’re a bit like bumpers except they operate semi-linearly, rather than radially. 4. Targets (Photo a4) – these are basically labelled switches that detect when they are hit by the ball, usually increasing the player’s score. They’re typically placed against the side of the machine, where the player can fling the ball (if they have sufficient skill). siliconchip.com.au 5. Rollovers (Photo a5) – these are designs drawn on the deck with a corresponding inductive sensor underneath. The machine detects when the ball rolls over the image, increasing the score or having some other effect. Photo a2: bumpers like this are scattered (or clustered) around the deck, giving the ball a little boost while flashing lights and making noises (and possibly adding to the score). Photo a3: kicker(s) work somewhat similarly to bumpers but in a more linear fashion. They’re usually attached to taut bands that push the ball away when the kicker moves them. where it started and moved the targets up the deck. Making a ball game with a bridge is the one thing I wanted to do as a kid. You will probably form your own opinions on the layout; there is nothing stopping you from moving stuff around. Mind you, by the time we were satisfied with our layout, the sales staff in our local electronics shop were convinced we were 3D printing a battleship! While we used Fusion 360 to design all our parts, for those at the start of a 3D modelling journey, there are much simpler tools like Tinker-Cad that you could start with. Our experience is that you need to be willing to try different versions of the overall layout until you find one that plays well. Photo a5: inductive sensors mounted under the deck form ‘rollovers’, which can add to the score or trigger other actions. The zones are indicated on the deck with decorations like circles or starbursts. Photo a4: aim the ball perfectly at these targets for bonus points! They’re illuminated and trigger microswitches when hit. Photo 2: the machine’s wiring is greatly simplified by using 10-way ribbon cable for most runs. Breakout boards at the far end make it easy to connect to LEDs, inputs and so on. Australia's electronics magazine June 2026  29 Electronic Parts The Pinball Machine uses more than a dozen boards, most of them breaking out ribbon cable connections to simplify the wiring. 1. Control Board (Photo b1) – this hosts the Raspberry Pi Pico 2 and a lot of I/O. It senses all the switches and other inputs, then makes decisions to take action, triggering various outputs like LEDs and solenoids. It also keeps score, keeps track of the current player, and controls the flippers and ball launching mechanisms. 2. Power Supply (Photo b2) – the whole machine is run from a 24V DC 5A ‘brick’. This board derives +5.5V and +3.3V rails from the incoming 24V DC, then distributes all three rails to the Control Board. 3. Player & Score Displays (Photo b3) – these are mounted on the backboard and show the current player number and their score. They connect to the Control Board with one 10-way ribbon cable per digit and are driven from 74HC595 IC outputs with current-limiting series resistors. 4. Cascade & Bumper LED Boards (Photo b4) – these simplify the construction of groups of LEDs that shine through small windows on the deck. They connect back to the Control Board via one or two 10-way ribbon cables for each assembly. 5. Bumper & Kicker Interface Board (Photo b5) – this connects up to three bumpers and two kickers to the Control Board. Placing it near those devices simplifies the wiring. It connects the switches back to Control Board inputs via a 10-way ribbon cable, with additional figure-8 cables for each solenoid. 6. Power Distribution Board (Photo b6) – this makes it easy to connect multiple solenoids or other Photo b1: the Control Board. It’s a bit of a monster, but all the parts are cheap, commonly available and easy to solder. In a sense, it’s just a Raspberry Pi Pico 2 with a lot of I/O. Photo a1: one flipper; a pair of these are what the player uses to move the balls around the deck and (hopefully) score points while avoiding the ball falling down the bottom, ending their turn. They’re driven by two solenoids each to give good ball acceleration! Photo b2: the power supply simply derives 3.3V and 5V DC rails to power the Pico 2, LEDs and so on from the 24V supply. It also passes the 24V supply through to power the solenoids and audio amplifier. The final version moves the output connectors to align with those on the Control Board. Photo b3: the current player and score displays are simple 7-segment LED digits mounted on a PCB. The current-limiting LEDs are on the Control Board. If your woodworking skills are strong, you could start by making much of the deck out of timber, such as plywood. That may make it easier to experiment. You can either paint it to get a good finished product, or replace pieces with 3D-printed plastic parts once you have finalised the configuration. Bite-sized chunks There are quite a few parts to this project, which we will describe in sections. This article presents the overview and how it all comes together, the architecture and top-level software description. Over the next couple of months, we will describe the electronic modules and provide parts lists along 30 Silicon Chip with assembly and testing instructions. That will include the controller and I/O board, plus several other related parts If you’re planning to build the Pinball Machine, that will give you time to gather the components and start getting the electronics up and running, which will help with testing the electromechanical parts later. Once all the electronic parts have been described, we will provide the 3D printing files and describe how to put those parts together. That will include the electromechanical parts such as the kickers, flippers and suchlike. You can make these ‘standalone’, purchase commercial versions, or even design your own. When all the parts have been fully Australia's electronics magazine explained, we’ll give more details on our example layout for the machine we built. This allows us to present how to bring this lot together; we hope inspires you to develop your own deck layout, artwork and gameplay. That means the construction details for this new Pinball Machine will be spread out over the next few issues, finishing before the end of the year. Pico 2 software The processing is all done by the Raspberry Pi Pico 2. We gravitated to this as it is so easy to use, powerful enough for the job, and inexpensive too. The design does need to grapple with somewhat limited I/O, but by normal standards, the Raspberry Pi has plenty. siliconchip.com.au higher-power devices to a single output on the Control Board. 7. Rollover Interface Board (Photo b7) – this simplifies the wiring to inductive rollover sensors, allowing up to eight to be connected to the Control Board via a single 10-way ribbon cable. 8. Input & LED Breakout Boards (Photo b8) – these simplify wiring to switches and LEDs, allowing up to eight of each to be wired back to the Control Board via a single 10-way ribbon cable. The three-pin headers are for inductive sensors, like with the rollovers. Photo b7 (above): this board makes it easy to connect up to eight inductive sensors to the Control Board via a single ribbon cable. Use more than one if you want more than eight rollovers! Photo b5 (lower left): this board provides a local connection point for the wiring of up to three bumpers and two kickers. All the inputs go to the Control Board via a single ribbon cable, while the solenoid drive comes from the Control Board via one figure-8 wire per bumper/kicker. Photo b6 (lower right): this allows you to connect several high-current devices to simplify the wiring. These are straightthrough connections with added flyback diodes. Photo b4 (above): these boards arrange 15 and 8 LEDs, respectively, and connect them back to 10-way header(s) for connection to the Control Board. Much easier than wiring them by hand! The software is essentially a state machine. There are two main modes: normal operation and Self-Test. If you hold the TEST button while it is booting, the machine goes into the Self-Test mode; otherwise, the system boots into normal operation. The software structure is shown in Fig.2. After normal initialisation, the system goes into the Idle state, monitoring the coin, player add and start inputs. The coin input can be a simple push button, but if you want to be a little bit fancy, you could create a coin slot. All it needs to do is pull the coin input low each time a coin is sensed. Once “Start” is pressed in the idle state, and assuming you have sufficient credit, the machine moves to the RunGame state. The system runs siliconchip.com.au Photo b8: these three input and LED output breakout boards simply break out the eight connections on the 10-wire ribbon cable to eight separate polarised headers for easy wiring and maintenance. Photos 4 & 5: the adjacent photo gives an idea of what the wiring is like on the underside of the Pinball Machine. The photo below and right is an expanded view of the Control Board wiring that is shown in Photo 2. Fig.2: the software has two main modes: test mode and normal gameplay. The code is written in Visual Studio C, and does nothing tricky, so most software-conversant people should be able to modify it. a loop that looks at all the inputs and, depending on changes to any inputs, triggers the required action: For the flipper, kicker, bumper and reload mechanism sensor inputs, this action is to trigger the associated solenoid for the required time, then to return to an idle state. Scores are incremented for some of these. The flippers are a little different; if the player holds these, the system continues to generate a solenoid output but with a lower duty cycle using pulse-width modulation (PWM) – there will be more on why that’s necessary later. For targets and rollovers, this action can be to light up LEDs and to increment scores. Sounds are triggered by these inputs or time passing. Because the majority of the pinball machine is fairly one-to-one causal input-to-output, you don’t need to use all the inputs or outputs. You have great flexibility in how you build your machine. We provide the source code as part of the download, so if this is your thing, you can modify the software to make it your own. Indeed, we encourage this. If you make something cool, please let us know and share it! Once the player loses and the ball 📍 📍 📍 32 Silicon Chip is sensed in the reloader mechanism, the system preloads the ball using a solenoid, and the player number increments. The system indicates the player whose turn it is on the main display and provides their score. Players have a total of three balls (programmable) and they take turns for each of their three balls in round-robin fashion. In the GameOver state, the system presents the score for each player in turn. Once this cycle completes, the system returns to the Idle state. We will describe the significant selftest capabilities of the software later, after we’ve built some of the hardware. During construction, this is probably the most important part of the code. Software development The Raspberry Pi Pico add-on for Visual Studio is a joy to use. Coming from a hardware engineer who turns the air blue every time software has to be written, this is high praise. While this author has generated many lines of code for this and other projects, every time I write code, it is an exercise in learning (and patience!). The Pi development add-on to Visual Studio with AI assistance is truly a generational step forward, and Australia's electronics magazine we encourage you to look inside the code and give it a crack. The best outcome is your own awesome machine, and the worst is you revert to the baseline code. Control Board The Control Board carries a lot of parts but is not that complex. Its heart is the Raspberry Pi Pico 2, mounted via a pair of headers. There is a small power interface and an audio section. The remainder is all buffered inputs and outputs (I/Os). This is required for the sensors and outputs such as LEDs and solenoids. The Control Board has six main functional areas, as per Fig.3. These sections are also delineated by silkscreen ink on the actual board; we will describe in general how the Control Board works below. Sensor inputs: the Controller monitors all inputs, including user controls like the flipper buttons, coin slot, start button and such. At the same time, it also watches gameplay inputs such as target sensors, rollover sensors and mechanism sensors on kickers and bumpers. State changes on these inputs trigger actions. This includes changes in the state of the game, the score siliconchip.com.au Pinball Machine Kits Note that we are supplying partial kits for this project, primarily for the Control Board and Power Supply - see the Online Shop on page 86 for details. and controlling outputs. The outputs affected might drive lights, bells, LEDs, or more active outputs like flippers and kickers. This would be really easy were it not for the sheer number of inputs and outputs. Low-power outputs: there are 40 of these, for driving the 7-segment LED displays that show the current player and score. They can source or sink about 8mA each. Medium-power outputs: there are 64 of these to drive LEDs for effects spread around the playing area. 16 of these sink around 30mA for driving white LEDs, while the other 48 sink around 20mA for red LEDs. You could change the current limit mix to suit your machine. High-power outputs: these are for driving solenoids and such, supplied from 24V, at up to an amp or more (although the 5A power supply limits the total current and thus the power of all loads). Control and audio section: this includes the Pico 2, a ‘heartbeat’ LED and the audio amplifier, which is driven from a PWM output on the Pico 2. Power supply interface: the separate Power Supply Board does all the heavy lifting here. The six-way siliconchip.com.au power connector on the Control Board matches that on the Power Supply Board. How will it all come together? The Control Board has a six-way pluggable connection to the power supply. There are seventeen 10-way IDC-style box headers for the inputs and LED outputs, and twelve high-­ current outputs to the solenoids and high-power devices via two-way pluggable terminals. The Control Board normally lives in the backboard cabinet on a pinball machine. The I/O wiring runs from this to distributed local boards, either for direct presentation of LEDs or local wiring to the sensors. By using lots of 10-way ribbon cables with IDC connectors at each end, we keep the wiring much simpler and neater than if single-wire spaghetti ran everywhere. That means your job will be much easier in building it. An initial prototype we built without using this system, instead using crimp connectors on individual wires, turned out to be quite annoying to build. Next month In the next issue, we will start by building the electronics, starting with the Control Board, then the Power Supply and the other electronics. After that, we will walk readers through the construction and testing of the bumpers, kickers, flippers and other 3D-printed parts. Then we’ll get to the fun bit – putting it all together into a cohesive game! Finally, overleaf you will find the part lists for all the electronics. If you’re keen to build the Pinball Machine, start gathering them and we’ll have the conSC struction details next month. Fig.3: the six main functional blocks of the Control Board, which you will find outlined on the board itself. Australia's electronics magazine June 2026  33 Parts List – Pinball Machine Electronics Modules Control Board (one required) 1 double-sided PCB coded 08107261, 246.5 × 240.5mm 17 2×5-pin boxed IDC headers (CON1-CON9, CON11-CON18) 4 2-pin polarised vertical headers, 2.54mm pitch (CON10, CON35-CON37) 1 4-pin polarised vertical header, 2.54mm pitch (CON20; optional, for future expansion) 12 2-way vertical pluggable terminal blocks, 5.08mm pitch (CON21-CON28, CON31-CON34) 1 6-way vertical pluggable terminal block, 5.08mm pitch (CON38-CON40) 2 20-pin header strips (for MOD1) 2 20-pin female headers (for MOD1) 1 SPST momentary PCB-mount tactile key switch (S1) 1 10kW logarithmic taper 16mm single-gang potentiometer (VR1) Semiconductors 1 Raspberry Pi Pico 2 microcontroller module (MOD1) 4 74HC165 8-bit parallel-to-serial shift registers, DIP-16 (IC1-IC4) 15 74HC595 8-bit serial-to-parallel shift registers, DIP-16 (IC5-IC9, IC11-IC18, IC22-IC23) 1 LM384N 5W power amplifier IC, DIP-14 (IC10) 12 IRLZ44NPBF N-channel Mosfets, TO-220 (Q21-Q28, Q31-Q34) 64 BC338 or similar 100-800mA NPN transistors, TO-92 ▲ (Q111-Q188 ■) 1 3mm or 5mm LED (LED1) 13 1N4004 400V 1A diodes (D1, D21-D28, D31-D34) 64 1N4148 or 1N914 75V 200mA signal diodes ▲ (D111-D428 ■) ■ not all numbers in the range are used ▲ it may be cheaper to buy 100 Capacitors 2 2200μF 35V electrolytic, 7.5mm pitch 4 470μF 25V low-ESR electrolytic, 5mm pitch 1 47μF 16V electrolytic, 2.5mm pitch 1 4.7μF 50V electrolytic, 2.5mm pitch 33 100nF 50V radial ceramic, 5mm pitch Resistors (all axial ¼W ±5% or better) 1 2.2kW 41 220W 3 100W 1 2.7W 145 1kW 48 150W 16 82W Power Supply (one required) 1 double-sided PCB coded 08107262, 106.5 × 83mm 1 miniature 5/5.08mm-pitch 2-way terminal block (CON41) 1 PCB-mount DC barrel socket (CON42) [Altronics P0620] 1 6-way vertical pluggable terminal block, 5.08mm pitch (CON43-CON45) 2 LM2576T-ADJ 3A adjustable buck regulators, TO-220-5 (REG1, REG2) [Altronics Z0589] 2 1N5822 30V 3A schottky diodes (D2, D3) 6 M205 fuse clips (F1-F3) 1 M205 5A fast-blow fuse (F1) 2 M205 2A fast-blow fuses (F2, F3) 2 100μH 3-5A toroidal inductors (L1, L2) [Altronics L6622] 3 2200μF 35V electrolytic capacitors, 7.5mm pitch 2 470μF 35V electrolytic capacitors, 5mm pitch 2 100μF 35V electrolytic capacitors, 5mm pitch 4 100nF 50V ceramic or film capacitors, 5mm pitch 1 3kW ±1% ¼W axial resistor 1 1.6kW ±1% ¼W axial resistor 2 1kW ±1% ¼W axial resistors Player LED display board (one required) 1 double-sided PCB coded 08107263, 37 × 52mm 1 red common-anode 12.7mm (0.5-inch) 7-segment single-digit LED display (DISP7) [Altronics Z0191, Mouser HDSP-511E] 1 2×5-pin boxed IDC header (CON107) Score LED display board (one required) 1 double-sided PCB coded 08107264, 142 × 51.5mm 6 red common-anode 12.7mm (0.5in) 7-segment single-digit LED displays (DISP1-DISP6) [Altronics Z0191, Mouser HDSP-511E] 4 2×5-pin boxed IDC headers (CON101-CON104) 2 BC338 or similar 100-800mA NPN transistors, TO-92 (Q1, Q2) 2 1kW ¼W axial resistors 12 220W ¼W axial resistors LED output board (one or more required) 1 double-sided PCB coded 08107265, 49 × 38.5mm 1 2×5-pin boxed IDC header (CON50) 8 2-pin polarised vertical headers, 2.54mm pitch (CON51-CON58) Bumper LED board (several required) 1 double-sided PCB coded 08107266, 84.5 × 84.5mm 1 2×5-pin boxed IDC header (CON48) 8 5mm ultra-bright clear-lens 20mA red LEDs (LED17-LED24) [Mouser 941-C503BRCNCW0Z0AA1] Cascade LED board (one required) 1 double-sided PCB coded 08107267, 89.5 × 99mm 2 2×5-pin boxed IDC headers (CON46, CON47) 15 5mm ultra-bright clear-lens 30mA white LEDs (LED1-LED15) [Mouser 941-C503DWANCCBEB151] Switch input board (several required) 1 double-sided PCB coded 08107268, 54.5 × 38.5mm 1 2×5-pin boxed IDC header (CON70) 2 3-pin polarised vertical headers, 2.54mm pitch (CON71, CON75) 6 2-pin polarised vertical headers, 2.54mm pitch (CON72-CON74, CON76-CON78) General Input board (one or more required) 1 double-sided PCB coded 08107269, 49 × 38.5mm 1 2×5-pin boxed IDC header (CON60) 8 2-pin polarised vertical headers, 2.54mm pitch (CON61-CON68) High-current interface board (one required) 1 double-sided PCB coded 08107260, 38.5 × 66.5mm 8 2-way vertical pluggable terminal blocks, 5.08mm pitch (CON91-CON98) 4 1N4004 400V 1A diodes (D4-D7) Rollover interface board (one or more required) 1 double-sided PCB coded 08117261, 65.5 × 38.5mm 1 2×5-pin boxed IDC header (CON80) 8 3-pin polarised vertical headers, 2.54mm pitch (CON81-CON88) Bumper driver board (one required) 1 double-sided PCB coded 08117262, 93.5 × 77.5mm 1 2×5-pin boxed IDC header (CON110) 11 2-pin polarised vertical headers, 2.54mm pitch (CON111-121) 10 2-way vertical pluggable terminal blocks, 5.08mm pitch (CON131-CON140) 5 1N4004 400V 1A diodes (D11-D15) 3 390W ±5% 1W resistors siliconchip.com.au