** 2 page EJP / 1803 words *** Team Tap Troubles Following several false starts Xav finally presents construction details for his DIY Team Tap... This time I'm happy to deliver an extra page and some files on the Reader Disk which take you right through the construction of a DIY Team Tap. All the files are also included on the Atari Computing renegade CD-ROM or from my web pages at: ** BC ** www.compsoc.man.ac.uk/~xav (then follow the Atari link) ** /BC ** In order to build the Team Tap you'll need a number of components, totalling around œ20 - although electronics hobbyists may have most of them lying around. Table 1 gives Maplins catalogue numbers, brief descriptions, quantities and approximate prices. The only thing not listed is a suitable box, which you will have to source for yourself. Are you sitting comfortably? Before you begin any construction, it will be necessary to cut the stripboard to the correct size using a strong craft knife and a great deal of care. You will need a piece of at least 30 strips by 33 holes, though if you are not used to working with it, it might be worth allowing a little excess. It will be easier to solder to if you clean the copper tracks by gently rubbing it with a piece of very fine, and preferably old, glasspaper. You can also buy abrasive rubbers designed specifically for this task - Maplins sell these, too. Of course, experienced solderers rarely perform this step - but then they can often be found swearing at solder joints that won't take to the copper. To ensure we are all talking about the same holes, you need to label your board. Looking at the component (non-copper) side, with the tracks running horizontally, the holes should be numbered from one to 30 downwards, and from A to Z, then AA to AE, from left to right. One of the best ways to do this is to stick the board to a piece of paper (on the component side), then label the paper. All your components can then be pushed through the paper, when required, which helps to hold them whilst you solder and also improves the appearance of the finished circuit. If you allow a paper border, you can label the holes there, then cut the edge off once the job is completed. It also helps to label the rear of the border, so you can see the track co-ordinates from the copper side - just bear in mind that the letters will have to run in the opposite direction! ** VEROBORD.GIF here ** Now would be a good time to look at the file TT_CONST.TXT on the Reader Disk or my web pages. This file contains details detailing which components go where, and is arranged by component type. As a general rule, circuits are best constructed from the lowest profile components to those which stand proud of the board. Consequently wire links should be the first items soldered into place and tall items such as capacitors should be amongst the last. Following this system helps to ensure that the components are soldered as closely to the board as possible, which gives the best looking result. ** On Reader Disk banner/logo here ** Secrets of success Although the text file gives details of what goes where, you may find the following tips helpful when constructing this and future projects. Track Cutting - This should always be the first step in any stripboard project. Basically it is the combination of the existing tracks, some well placed cuts, and the wire links which define the interconnections between the components themselves, so it's very important to get this step right. Track cutting is usually undertaken by removing a section of the copper using a drill bit. The bit should be very slightly wider than a single track, and should be twisted gently in the named hole, on the copper side, until the track is broken. This is the main reason for numbering the holes on the track side as well as the component side. Resistors: These can be placed either way round. If the legs need to pass through holes which are quite close together it's common to mount the components vertically. In this case the body of the resistor extends away from the component side of the board, rather than lying against it. Whenever you bend the legs of any component it helps to prevent damage if you can make the bend a little way from the body of the device. This means that it is often better to mount a component vertically than to force the legs to make a tight bend in order to accommodate the hole positions. Diodes: Similar mounting tips to resistors apply here, but diodes have to be fitted a particular way round. In this particular circuit, all the diodes should be mounted vertically. If you bend the legs of all the diodes to shape before you start mounting them, you can easily ensure that the identifying stripes are aligned, making it easier to spot when one of them is inserted the wrong way round. PCB Pins: These are the preferred method of connecting the wires from the plug and sockets. They are inserted from the track side, not the component side, and are usually forced into place with a hot soldering iron (please be very careful!) before being soldered to ensure a good electrical connection. The wires are then connected to the pins from the component side. This has the advantage that any mistakes can be remedied quite simply, because it is easier to remove a wire from a PCB pin than to desolder it from the track side of the circuit board. Integrated Circuits: These can be quite sensitive to prolonged heat from a soldering iron, so it's common to use so-called DIL sockets. These are soldered into the same location as the IC itself, then the IC is pushed into the socket as one of the final stages of construction. The 74HC154 IC used in this circuit poses its own particular set of problems because it's available in both wide and narrow packaging. One of the reasons for the delay between articles in this series was that I was forced to scrap my first prototype, which assumed the narrow packaging. The circuit has since been redesigned to allow space for either - you just have to ensure that its legs span the cut tracks at L17 to L28. If you have a narrow socket and a wide IC, or vice versa, you can cut the socket in half along its length, trim as appropriate and solder the two halves into the holes at the correct spacing. Capacitors: Like diodes, electrolytic capacitors, must be connected a particular way round otherwise they can explode! Please read the connection list in TT_CONST.TXT carefully! Plugs and Sockets: Connecting these should be the penultimate action. Deal with one wire at a time, and double check the connections as it is easy to mis-count the pins. Although the PCB pins are listed in the text file in order from top left to bottom right, you will find it easier to deal with the connections to the middle row of pins on the plug and sockets first of all (i.e. pins 6 to 10). A soldering iron with a small tip will prove invaluable here, and you have to be careful not to use too much solder. This is the most likely stage for "solder bridges" (erroneous connections due to too much solder bridging between conductors) to form, so double check everything. Testing, testing After the plug and the first socket have been connected you can test the circuit by fitting the ICs into their sockets (note their orientation) and putting the whole circuit in-between your joypad and Jaguar/computer. If everything is working properly there should be no difference, as the first socket effectively passes the standard joypad signals straight through. The best way to test the full functionality of the joypad is to use KP EJP Tester from RD#4. This is also available from my web pages and is also on the Atari Computing renegade CD-ROM. Assuming everything is okay, you can continue to fit the remaining three sockets. However, if your computer or games console fails to boot up as expected, switch off the power immediately and double check all your connections. Similarly, if KP EJP Tester does not react to the buttons you are pressing, or if they seem transposed, double check everything. It is likely that you simply cross-connected the plug or sockets, but you should check carefully for solder bridges between the copper tracks of the stripboard, and also that you have made all the required track cuts at all the right locations. Once you have connected the remaining sockets you need to perform a more comprehensive test. C hackers amongst you should be able to construct a simple test program based on the information and samples given with earlier instalments, everyone else will have to wait until the next issue, when we will look at addressing the Team Tap in your own code. If you have a Jaguar and a copy of White Men Can't Jump or NBA Jam you should be able to conduct a test based around these, as they both support use of the Team Tap. Be warned, however, that for WMCJ at least, the Team Tap needs to be plugged into the second joypad port, not the first - I wasted several days checking my circuit because I wasn't aware of that snippet of information! ** Boxout 1 ** Circuit Diagrams There's a detailed drawing of the finished circuit on my web pages and on the Atari Computing renegade CD-ROM in DXF and GEM format. The DXF drawing has each component type on a separate layer which makes it easy to see where each component goes. The GEM file is split into two, with all the components on a separate drawing. ** DYNACDXF.IMG here ** ** Caption ** DynaCADD can read DXF format files ** /Caption ** ** ARTWRXGEM.GIF here ** ** Caption ** Artworx, Kandinsky, EasyDraw, Calamus and other applications can open GEM format files ** /caption ** If you print the relevant layers at a scale of 25.4:1 you'll have a template to stick onto your stripboard. ** On renegade CD logo here ** ** /boxout 1 ** ** Boxout 2 ** ** Table 1 ** Table 1: Maplin Order Codes CODE DESCRIPTION QTY TOTAL PRICE JP51 Stripboard 1 œ3.83 FL24 PCB Pins 1 œ2.55 QL80 Diodes 25 œ1.90 M1K 1K Resistor 1 œ0.06 M4K7 4K7 Resistors 6 œ0.36 UB38 74HC154 1 œ1.27 BL20 24 way DIL Socket 1 œ0.20 AE26 74HC244 1 œ0.63 HQ77 20 way DIL Socket 1 œ0.21 YR75 0.1uF Ceramic Disc Caps 2 œ0.36 AT29 47uF 10V Electrolytic Cap 1 œ0.16 JW77 HD 15 way D Plug 1 œ1.36 JW78 HD 15 way D Sockets 4 œ6.78 ** /boxout **