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Background image: https://unsplash.com/photos/gaming-room-with-arcade-machines-m3hn2Kn5Bns Skill Tester 9000 Part 2 – by Phil Prosser This retro game is a fun and educational project to create a dexterity-based game with nine difficulty levels, a health bar graph, a timer and four different sound effects. It is based mainly on 4000-series logic and all through-hole parts on a single circuit board. T here are some sections of this game that advanced constructors can customise, such as changing the winning and losing tunes, but we will describe the assembly process for the standard version. There is definitely scope for customisation when you make the wire ‘obstacle course’, as you can make it as easy or as hard as you want! The assembly instructions will be given in seven discrete steps. After adding the parts for each step, you will have new functions to test, so you can pick up any problems early on and fix them before tracking them down will be more difficult. You shouldn’t need any special tools; a soldering iron, solder, fume extractor and a multimeter for testing should be all that’s required. Construction We will build the Skill Tester 9000 section by section and test each as we go along. This allows people to work with young constructors or students in simple sessions, achieving visible progress in each. Even as an experienced constructor, I build projects in 80 Silicon Chip bite-sized chunks as it makes debugging simpler and there are built-in coffee breaks. The Skill Tester is built on a double-­ sided PCB coded 08101241 that measures 174 × 177mm. During construction, refer to the PCB overlay diagram (Fig.5) and Photo 1 to see which components go where and how they are orientated. Here are general cautions and instructions you should keep in mind during the construction process: • Ensure all diodes are fitted the right way around (stripe to the right or down on this PCB). • All LED cathodes are upwards; LEDs have a chamfer (flat edge) on the cathode side. • All ICs are installed with pin 1 to the right. If you get one backwards and are not using sockets, you will have to cut all pins off using side cutters and pull individual pins out (unless you have a hot air rework station). • Check the supply rail voltage every time you power it up after adding parts. We have included a ground test point, with a 9V test point close by Australia's electronics magazine (below IC1). You should measure more than 8V between the two with a fresh battery. If not, something is wrong. • If something is wrong and, while you are investigating, the noise from the speaker is slowly driving you insane, put a 1kW resistor in series with the speaker to tone things down a bit. • Standard checks as you solder: are there any solder blobs shorting pins? Is each solder joint shiny with the right shape? Has the solder adhered to both the component lead and the PCB pad? • For each polarised part, check before and after soldering that it is the right way around. Also check the part numbers of ICs and double-check the orientation before you solder them. • If you need to check clock signals and don’t have an oscilloscope, put your DVM on its AC setting and probe the test point. You should measure a few volts AC or see pulses in the reading for very slow clocks. Touch, Win & Reset sections 1. Let’s start construction with the siliconchip.com.au D51 5819 1kW 100nF 47nF 10kW D18 4148 D21 4148 D44 4148 D47 4148 D48 4148 D46 470kW 10kW 4148 D43 680kW 10kW 680kW 220kW 220kW 120kW 120kW 120kW 220kW 220kW 220kW 270kW 270kW 10mF 100nF 470kW D45 4148 D29 4148 D32 4148 D33 4148 D35 D34 4148 4148 D37 D36 4148 D38 4148 4148 D41 100nF 10nF 100nF 10kW 4148 10kW D42 4148 4148 270kW IC14 NE555 1kW 4148 D23 4148 100nF 100nF 100nF 10mF IC15 4093B 100nF 100nF 24kW 10kW 22kW 27kW 24kW 24kW 24kW 27kW 18kW 18kW 18kW IC13 4017B D53 270kW 100nF 1kW 56kW 330nF 1mF 100nF IC9 NE555 10mF 10kW 1kW 100kW 10mF 100nF 10kW D17 D16 4148 4148 D19 D20 4148 4148 D22 D24 4148 D25 4148 4148 D26 10kW D27 4148 4148 D10 IC88 44001177BB IC 4148 4148 4148 1kW D11 D28 4148 IC11 LM386N 100nF 4148 D14 10kW D39 D40 D52 4148 D30 4148 4148 D31 4148 10kW D13 IC12 4013B 330nF D8 + 1kW 1kW 1kW 1kW 1kW 1kW 1kW 100nF 10kW D55 4148 220mF 56kW CON4 56kW 470mF 10W 100nF 4148 10kW 4148 SPEAKER CON6 GROUND + 1kW 4148 10kW 100kW IC7 4013B 100nF 4148 D3 CON1 9V BATTERY HOLDER 100nF IC4 4013B 56kW 4148 CON3 D5 100nF IC6 NE555 IC1 CD4026B + 470nF D1 DP 100nF 100nF LED11 RESET 4148 D49 1mF D 56 Reduce to make harder 4148 4148 56kW D50 4148 270kW D4 10mF 10mF 22mF 9V IC5 4081B 10kW 4148 IC17 4093B 1kW D6 100nF 4148 D2 D15 D12 8 S1 S2 COMMON CATHODE 1kW D54 4148 10kW 100kW 4148 D9 D7 100nF 10kW 4148 4148 4148 56kW IC2 NE555 IC3 4017B 100nF 1kW CON2 1kW 1kW Health Time LED16 LED17 LED15 LED15 LED12 TOUCH LED13 WIN WIN 1kW 1kW 1mF LED14 SEQ. 470nF 33nF LED1 1kW 1kW LED2 LED3 1kW 1kW 1kW LED4 LED5 LED6 1kW LED7 1kW 1kW LED8 LED9 1kW LOSE DS1 7-SEGMENT LED – LED10 1kW S3 4.7nF 08101241 Fig.5: this overlay diagram shows which components go where. It also shows the correct orientations of all polarised components like ICs, diodes and electrolytic capacitors. It is divided into 11 sections and can be assembled all in one go if you are confident and experienced, or in the seven steps outlined in the article text. Touch, Win and Reset circuits. Fit all the parts in the Win, Reset and Touch areas of the PCB, plus LEDs LED11LED14 and the four associated 1kW series resistors. Also install IC17 (4093B), the 100nF capacitor next to it, power switch S1, 1N5819 diode D51, the battery holder and the 470μF capacitor just below the holder. When inserting the DIP ICs into the board, you may have to bend their leads inward a bit as they will come splayed outwards. siliconchip.com.au Put a battery in the holder and check that the 9V rail is OK. If not, is D51 the right way around? Is S1 switched on? Now short the terminals of CON3 (eg, using a short length of wire). You should see the Reset LED (LED11) turn on. Repeat this for the Win and Touch inputs at CON4 (with LED13 lighting) and CON2 (with LED12 lighting). If that does not work, are IC17 and the diodes the right way around? Measure the voltages on the input Australia's electronics magazine connectors; one terminal should be at 0V, while the other should be pulled up to 9V. If only one input does not work, look for solder bridges, especially on the pins of the 4093 chip, IC17. Check that its pin 2 goes low when you short the Reset pads and pin 3 goes high. Verify that its pin 9 goes low when you short the Touch pads and that pin 10 goes high. Also test that its pin 6 goes low when you short the Win pads and pin 4 goes high. May 2024  81 Photos 1 & 2: the fully assembled Skill Tester shown with the game wand (which is just a looped wire fitted into a pen case). The design is intended to be assembled in sections as marked on the silkscreen. During construction, you can test each section as its completed. At this point, you should be able to trigger Reset and exercise the Touch and Win inputs and see the corresponding debug LEDs light. Health section 2. Now let’s build the Health Clock and LEDs. Fit all the parts in the PCB section labelled HEALTH. Do not miss the 10kW resistor just below IC3. Get the selection of your coloured LEDs for LED1-LED10 right! We used low-cost LEDs with similar brightness. Make sure the switch you use for S3 is a centre-off type, so you have three difficulty levels. Apply power to the board and check that the 9V rail is OK. You should see LED17 come on. Short the pads of the Touch input (CON2), and you should see LED1-LED10 cycle continuously. Short the RESET pads (CON1), and LED17 should relight. If the above works, great, let’s move on. If it does not work, check that there is a clock signal at pin 14 of IC3. If the 82 Silicon Chip clock signal is missing, check around IC2. Short the Touch pads and check that pin 4 of IC2 goes high. If it still isn’t working, Check that IC3’s CP0 (clock enable) pin (pin 14) is low. If not, is there a short, or did you forget to fit the 10kW resistor? Are your LEDs the right way around? Check the Out Of Health signal on pin 12 of IC3 (4017); it should produce a square wave once per LED cycle. Check that the debug LEDs for Touch and Reset still work; if not, retest the input circuitry. At this point, LED1LED10 should be cycling continuously. 7-segment display should count from 0 to 9 continuously. If there are any problems, use a similar testing procedure to the section above, but with IC6 and IC1. The 555 (IC6) clock output is at pin 3, and the 4026 (IC1) clock input is at pin 1. The clock inhibit pin on the 4026 (pin 2) should be low, and Reset pin 15 on the 4026 (IC1) should be low. Shorting the reset pads (CON3) should reset the counter to 0. The pin 5 carry output of IC1 should cycle high and low once per 0-9 count. The Time counter should be running continuously unless you trigger Reset. Time section Siren and Tick section 3. Next comes the Time section and its 7-segment LED display. Fit all the parts in that area. Ensure that all parts in the Time and Health areas are on the board now. Verify that S2 is a centre-off type so we get three difficulty levels. Apply power to the board and check that the 9V supply is OK. The Australia's electronics magazine 4. Fit all the parts in the Siren and Tick area of the PCB. Watch out, as the 1μF capacitor may look the same as the 10μF capacitors. Also solder IC5, the 4081B in the Game Controller section and the parts immediately around it: the 100nF capacitor next to it, two 10kW resistors (one to the right siliconchip.com.au and one below IC5) and the six diodes immediately below IC5. Mount the speaker by gluing it in place with a few small dabs of super glue, silicone sealant or Araldite. Keep it tidy (ie, avoid getting glue where it shouldn’t go). Wire the speaker to the pads for CON6; you can omit the actual screw terminal or mount it on the underside of the board. Apply power and check the 9V rail. You should hear a warbling ‘ping’ from the speaker; that is the Time Clock tick. Switch the Time switch between Slug, Cheetah and Nightmare. You should hear the ticks change pace from very slow to very fast. If there is no sound, probe pins 10 and 11 of IC15 with an oscilloscope or multimeter reading AC volts. There should be AC signals on both. If so, short out diode D43, and you should get a lot of noise from the speaker. In that case, there is something wrong with C44, D47, C46 and the associated parts. Are those capacitors the right way around? Now short out the Touch pads (CON2). You ought to hear a racket from the speaker (the Touch tone). If not, check for an AC signal on pins 3 and 4 of IC15. The signal at pin 3 will have a low frequency, so you will be able to detect the individual pulses. Check that the Touch LED (LED12) lights when you short the Touch pads. If it still isn’t working, check for shorts on the board and parts missing or the wrong way around. At this point, the ticking sound should be running non-stop, and the Touch tone should be generated if you short the Touch input pads (CON2). Win Song section 5. Now fit all the parts in the Win Song section. There are a lot of different value resistors in the tune section; double-check the value of each before you solder it in. Getting resistors off a double-sided board is possible but not easy. If you are not 100% sure, measure each resistance with your multimeter. Remember to avoid touching the meter probes when doing this, as that will affect the measurement of high resistances. The 1μF capacitor and 270kW resistor just below IC17 should also be fitted to the PCB now. They set the period of the tune sequencers. siliconchip.com.au Apply power to the board and check the 9V rail. You should hear the ticking timer noise and the Win Song playing repeatedly. If there is no sound or only a single tone, check IC8 and IC9 for solder bridges. Also check around IC17, as it generates the clock for the tunes. Probe pin 14 of IC9 with an oscilloscope (or multimeter on AC volts). You should find a signal at about 2Hz. Check pin 3 of IC9 (555 timer). It should have an audio-frequency AC signal on it. Are those capacitors and diodes the right way around? At this point, you should have the Win Song running continuously on top of the ticking sound. Lose Song section 6. Fit all the parts in the Lose Song section, then apply power and check the 9V rail. You should hear the time ‘ping’ with a crazy noise in the background, which is the Win Song and Lose Song playing on top of each other, Short pins 1 and 4 of IC9 (555) to stop the Win Song so you can hear the Lose Song by itself. Be careful not to touch any other pins or parts, while doing this. If that makes no difference, probe pin 14 of IC13 with an oscilloscope or multimeter on AC volts. You should see a signal at about 2Hz. Pin 3 of IC14 (555) should have an audio-frequency AC signal on it. Are those capacitors and diodes the right way around? You can stop the Win and Lose tunes independently by connecting a wire to the ground point, then touching the other end to pin 4 of IC5 or IC14, resetting that 555 and stopping that tune generator. At this point, you should have some crazy noises happening while power is applied. The Game Controller 7. We have built and tested each part individually, and you should understand how each section operates. Let’s bring them all together by adding the control components. Fit all the remaining bits, with the usual cautions on getting ICs in the right way around and choosing the right one for each spot. Apply power and check that supply voltage again. The game will start straight off the bat. You should hear ticking, and if you short the Touch pads (CON2), you should hear the Touch noise. Australia's electronics magazine You should hear the Lose Song after the Time counter gets to 9. Try shorting the Reset pads (CON3), which should restart the game. If you short the Win pads (CON4) immediately after starting a game, you should hear the Win Song. If that is not happening, verify that all polarised parts are fitted the right way around, especially the diodes. Check for bad solder joints or bridges (shorts) between adjacent pads, or components that have been mixed up or misplaced. The diagnostic LEDs (LED11LED17) show the state of every latch and input. Our earlier tests showed that the inputs were working, so check everything around IC4 and IC7, as the latches are there. Are any pins shorted? Mounting the PCB Our baseboard was about 500mm long and just deeper than the PCB. How you go about this part of the construction process should reflect the space you have and what you want this game to be. We marked the holes for drilling by putting the completed PCB on the board and drawing through the holes with a marker, then drilling 4mm holes at those points. We had shorter screws on hand, so we countersunk the holes on the back of the game board to get a bit of extra length so our screws reached the standoffs on the top side of the board. Once you have successfully mounted the PCB, remove it to work on the game wire, including the Reset and Win parts at each end. We routed the edges of our board and painted it with clear lacquer to make it tidy. The charm of this project is its nostalgic design and concept, which relies in no small part on a tidy appearance. You need to put some rubber feet on the board, in the corners of the underside. Otherwise, the screw heads will scratch everything you put it on, and it will slip around. Stick-on rubber feet work well. The game wire We used some fencing wire from the shed for this. It is about 2mm thick and pretty solid; it can be bent with pliers or your hands for smoother curves but is tough enough to take a hiding. You want to use steel wire as copper May 2024  83 Photo 3 (left): this photo shows how we secured the game wire to the baseboard. It also shows the wire wrapped around it to form the Win contact (with heatshrink tubing underneath) and how that copper wire connects back to the terminal on the PCB. To attach it to the baseboard, the main wire was bent into a loop just larger than the bolt diameter using sharpnosed pliers. Photo 4 (right): a view of the Reset end of the maze wire, showing how the start contact is bare copper wire from domestic mains cable, wrapped around the heatshrink insulation and soldered in place. Tinned copper wire would also work here. This is also the point that the main game wire is electrically connected to the Touch terminal on the PCB. won’t spring back. It doesn’t need to be fancy or new. If you are scratching your head, look in your wardrobe for a metal coathanger. I reckon that would work just fine. The shape of the maze is up to you. The tighter the kickbacks and the more changes in direction, the harder the game will be. A loop makes the game super hard as the wand has to be rolled to the back of the game to achieve this; that might be for more advanced gamers. Photo 3 shows how we bent the wire to go through the screws on the game board. We drilled holes for 30mm “gutter bolts” about 30mm apart, allowing space for a bolt to hold the game wire and a spot for a second bolt to connect to the Win and Reset wires at each end of the maze. We did this to make the whole thing robust, and so we could pull the wire maze off and put in an easier or harder one later. Our first maze had loops, tight corners, and all sorts of complex curves, making it nearly impossible to play. We suggest you instead start simple and work from there. Once you have your maze bent up, but before you bend the loops for the bolts, insulate about 50mm at each end with a couple of layers of heatshrink tubing. That will allow us to wrap 10-20mm of bare copper or tinned copper wire around the outside to form ‘pads’ that we will connect to the Reset and Win inputs on the game board. These inputs have a pullup on the game board, so if we touch these pads with a grounded wire, we will trigger 84 Silicon Chip Reset or Win, respectively. Our wand will connect to ground, making a neat arrangement for these inputs to the game. The required wiring is shown in Fig.6, although it does not show the physical layout, just what connects where. After you have applied the heatshrink tubing, tightly wrap your copper wire around it. Use pliers to ensure it is tightly in place, then solder the top and bottom of the loops together. Don’t worry; the heatshrink will survive; we put two layers just to be sure. This is shown in Photos 3 & 4. We left enough wire to run to a bolt where we connect Reset and Win to flying leads from the game board. The wand For the wand, we want something that is comfortable to hold and to which we can fix the wire loop that goes around the maze wire, connected to our circuit ground. By connecting the loop on the wand to ground, we can tap this on the Reset wire to start the game. If the loop touches the maze wire, it connects to Touch and, at the end of the game, tapping on the Win wire wins the game; all parts of the maze wire. We used a ballpoint pen case for the wand (Photo 5). The loop was made from the same wire, reclaimed from house mains wiring, that we used to make the Reset and Win pads. Fig.6: this diagram shows how the Touch, Reset and Win terminals (CON2CON4) connect to the wand, game wire and start and finish pads. Refer to the photos to see how we made the required electrical connections, and note that the ground wire going to the wand can connect to the upper screw of any of the three terminals. Australia's electronics magazine siliconchip.com.au Photo 5: we made the wand from an old biro case, some reclaimed wire (tinned copper wire could be used) and enough layers of heatshrink tubing added to make it a snug fit to the case. Some super glue holds the whole thing together. Assembly is a simple matter of screwing everything together. Make sure that the wand’s loop is ultimately wired to a ground pin on one of the Reset, Touch or Win connectors (CON2, CON3 or CON4). In each case, the ground side is closer to the top of the board. By now, you will realise there is a bit of work in making this project and doing so tidily. Still, the basics of a stable base, something to screw the wire to and wide enough to hold the PCB are the essence (see Photo 6 for our completed version). Finishing it off Connect the pad at the start of the wire to the Reset line (not the ground side, so the bottom terminal of CON3) so that tapping the wand here will start the game. Connect the main wire to the Touch connector (bottom of CON2), so touching the wand to the wire will short the Touch pin and reduce the Health counter. Connect the pad at the end of the wire to the Win connector (bottom of CON4). This way, everything you need to run a game is at your fingertips. Tips on playing There are three settings each for speed and difficulty. Noob + Slug makes the game the easiest, while Veteran + Nightmare makes it the most difficult (perhaps impossible)! So start with Noob + Slug and work your way up from there. To win, you must move the want from the start to the end of the wire with time and health left. To play a one-on-one game, choose a difficulty setting and play one game each. If one player wins and one loses, the winner is obvious, but if both win, whoever has the most health left wins. If both have full health left, the fastest time wins. To run a tournament, start with the easiest settings and give each player one attempt at the game. Anyone who loses (whether by running out of time or health) is eliminated. If more than one person is left, play again on a higher difficulty setting. Repeat this until all but one has been eliminated, or you reach the highest difficulty setting. In the latter case, use the rules above to determine the winner. When increasing the difficulty, we suggest going from Noob to Veteran for Health first, then when you reach Veteran, start speeding up the time from Slug to Nightmare. Also, remember that the way you bend, fold and make loops and kickbacks in that wire plays a big part. Is your wire tough enough? Have fun! If you come up with better tunes than we have, send in your resistor values so we can try them SC ourselves! Photo 6: the finished and assembled Skill Tester game. It is an updated version of the old wire loop (also called buzz wire) game. We’ve used an MDF offcut, but you can use whatever timber you have available as long as the size is adequate. siliconchip.com.au May 2024  85