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No more boring old buzzers for us . . . Let’s get Quizzical! We’ve all seen them: boring electronic quiz games which sound a buzzer or bell and light a light to tell you which contestant has pressed their button first. Ho-hum. Yawn. But there’s nothing boring about our QUIZZICAL! It will certainly judge the winner – even if there’s only microseconds between contestants hitting their buttons! But wait, there’s more: you don’t just hear a buzzer or bell, you hear a sound effect or tune that’s different for each player. And you can change that sound effect or tune whenever you like. I f you’ve ever watched the quirky British show “QI” (here’s today’s trivia or tomorrow’s quiz question – it stands for Quite Interesting), or perhaps the witty Aussie “Talking About Your Generation” you’ll know what we are talking about. When each player or contestant presses their buttons (well, more often than not, belts their buttons!) as well as judging who’s first, each responds with individual sound bites. Those sounds are often surprising, sometimes outrageous and always humorous. And they’re never the same from one episode to the next. Build the SILICON CHIP Quizzical! and similar, virtually limitless sound possibilities are yours. That’s because the Quizzical! uses a Secure Digital (SD) memory card to store the sound files and so any MP3 file can be included for play. There is no limit to the types of sounds that can be produced – any12  Silicon Chip thing from animal noises, explosions, opera and classical music through to one liners from cartoons, comedy skits or movies. Like “Go ahead, make my day!” How? If you know how to save an MP3 sound file on your computer and can then copy that to an SD card, you can use the Quizzical!. It doesn’t record files itself; it simply plays back files that have been stored onto the SD memory. What? For suitable sound files, you don’t have to search far. In just a few minutes searching on the net, we found literally millions of MP3 files. These ranged from Warner Brothers Bugs Bunny cartoon classic one-liners, by JOHN CLARKE Monty Python sound bites, Star Wars and other science fiction sounds, bell sounds and music MP3 files and ring tones. You can edit sound files to any length before placing these onto the memory card. If they are other formats (eg .WAV or .M4A) there’s plenty of free software around to convert them to MP3. Or you can record your own sounds using an MP3 player with recording facility or using a computer and microphone and freely available software. Even bits of CD tracks can be converted to MP3 format suitable for the Quizzical!. (Bear in mind the warning in the “Legalities” panel). Who? Quizzical! caters for up to four contestants plus the adjudicator (dare we call him the QuizzMaster?). Once a player has pressed his or her button to answer a question, his/her unique sound siliconchip.com.au      Quizzica l! Features • Up to four contestants plus QuizzMaster • Unique sounds played for each contestant • Unique sound during answer period and at end of answer period • Up to five separate set s of theme sounds can be stored on SD card • Internal speaker • External speaker output connector • Volume control • Optional externally-acce ssible SD card slot • Adjustable contestant play sound period • Adjustable answer per iod • Unlimited types of sou nds possible starts to play and his/her button lights up. And all other answer buttons are locked out at this time. The contestant sound play period can be set by a trimpot adjustment and is available from between 1.3s and 18s. But if those periods are not suitable, there is also the option to have the play period set by the sound file length. The QuizzMaster can cancel any sound playing by pressing the QuizzMaster button. This pushbutton also has a LED indicator. Additionally, the QuizzMaster can start a timer to limit the time period allowed between the quiz question and for an answer. During this answertiming period, a new sound (the QuizzMaster sound) can be played. When? This answer-timing period can be siliconchip.com.au set internally to between 1.3s and 35s or by the file length itself. At the end of the timing period, a different sound can be played to indicate timeout. The QuizzMaster LED lights during the answer-timing period. If another contestant presses a contestant button during the answertiming period, then his or her contestant sound is played. But that sound arrangement is quite flexible – you have the choice to play a “silent” file during the answer-timing period which, of course, means that no sound is heard. At the end of the answer-timing period a sound indicates the time has expired. Or you could have a sound played during the answer-timing period with a silent file for the end of the timing period. If the ans w e r- t i m i n g feature is not required at all, the QuizzMaster does not press the QuizzMaster button to initiate the answer-period. If the QuizzMaster button is pressed unin-tentionally, the button can be pressed again to immediately cancel the answer period sound. The contestants’ buttons still operate in the same way, where as soon as one button is pressed the other contestant buttons are inactive until the contestant sound file finishes playing. Themes and variations! The Quizzical can include up to five separate sound themes that are written onto separate folders on the October 2011  13 14  Silicon Chip siliconchip.com.au A K K  LED1  A 5x 100nF OR 6 9 7 12 10 3 13 15 16 17 5x 68  (a) or 5x 330  (b) 4 10k S (b) RB0 RB3 RB1 RB6 RB4 RA4 RB7 14 RA2/AN2 RA3/AN3 Vdd 5 Vss K  LED A RB2/Rx RA1 RB5/Tx IC1 PIC16F88 -I/P RA6/OSC2 RA7/OSC1 RA0 MCLR/RA5 (b) 330  TO DRIVE 1x RED LED (ONE OF THESE FOR EACH CONTESTANT AND QUIZMASTER) S R T QUIZZICAL! K  A S T R S T R S T R S T R S T (a) 68  TO DRIVE 3x WHITE LEDS 8 18 11 VR3 10k VR2 10k (ONE OF THESE FOR EACH CONTESTANT AND QUIZMASTER) S R T ANSWER PERIOD 1 2 PLAY PERIOD 100nF Fig.1: the circuit consists of the player push-buttons/LEDs, a PIC microcontroller, a proprietary MP3 module and an audio amplifier. Construction shouldn’t take much more than an hour or so. The five resistors between the sockets and PIC can be 68 (for the modified shed lights) or 330 if you use a single red LED in the box. 2011 SC S (a) (QUIZZMASTER) CON5 (CONTESTANT 4) CON4 (CONTESTANT 3) CON3 (CONTESTANT 2) CON2 (CONTESTANT 1) CON1 R +5V 13 15 IN SD1 EXTERNAL SD CARD CONNECTOR (OPTIONAL) * 19 CD WP CD WP MP3 MODULE TDB380 20 GND SD CARD CONNECTOR IN MODULE * BUSY Rx 100 F 16V OUT REG1 7805 7 6 5 4 3 2 1 9 8 7 6 5 4 3 2 1 9 8 R L 17 18 47 47 100 F 16V K 1N4004 A 100nF 100 F 16V * NB: USE ONLY ONE SD CARD CONNECTOR AT A TIME (NOT BOTH!) VR1 1k VOLUME NP 10 F +11.4V +11.4V 2 3 1 4 A K IC2 LM386N 6 LED 10 F 7 5 2.2k K 8 K IN GND 47nF 10 470 F A D1 1N4004  LED6 A POWER S6 OUT 7805 – + GND INTERNAL SPEAKER CON6 EXTERNAL OUTPUT CON7 12V DC INPUT SD memory card. By way of example, the first folder might contain the four separate files for the contestants, an answer period file and end of answer period file, all based on a cartoon theme. The second folder might have a science fiction theme and the third folder might have a classical music theme and so on. Other uses The MP3 module which the Quizzical! is based on is quite a useful little device. So much so that we imagine the Quizzical! will not be restricted to games use. The push buttons can be used for other purposes to initiate sounds. Perhaps you’d like a doorbell where each doorbell push-button switch gives a different sound? Easy with the Quizzical! Alternatively, the Quizzical! could be used simply as a sound bite generator to generate a variety of sounds on demand. Want to introduce sound effects to a school play? Store ’em on the Quizzical! and play them (perhaps over a PA amplifier?) at the appropriate time by pressing the appropriate button. But its main use is, of course, for quizzes and games. You could take control over all the contestant and QuizzMaster buttons and play suitable interjection noises associated with answers: for example cheers for correct answers, boos for incorrect answers. You get the picture (or actually the sound), we’re sure. Inside the Quizzical! case – this does have the external SD card slot added but it’s under the PCB. Fig.2, below, shows how and where. S T S T S T T S CON2 CON3 CON4 CON5 CON6 R R R R R R 100nF 100nF 100nF 100nF 100nF * * * * E MA G ZIU Q 11101180 SOLDERED TO POT BODY LED6 A 10 F NP LINK 47 47 47nF 10 VR3 100nF 100 F SY RX D 10k 100 F 1 2.2k VR2 * REG1 20 K 470 F BU GND L R 12V 7-WAY ICD SOCKET STRIP 100nF SPEAKER OUT IC2 LM386 * 5 x 68  (a) OR 5 x 330  (b) TDB380 MP3 MODULE S6 IC1 PIC16F88 4004 D1 QUIZZICAL! siliconchip.com.au S T CON1 CON7 Physically speaking . . . Quizzical! is housed in a small plastic case, which contains all the electronics except for the contestant and QuizzMaster pushbutton switches. These are connected via suitable lengths of twin shielded cable and 3.5mm stereo jack plugs which connect into the back of Quizzical!. We’ll have more to say on these pushbuttons a little later because we have something pretty special lined up there . . . There is a small loudspeaker within the case to produce the sounds but for best sound, a socket is included to connect a larger loudspeaker or for connection to a sound system. When a jack plug is inserted into this socket, the internal loudspeaker is S T SD1 (OPTIONAL – UNDER) 10 F 100 F VR1 1k LOG 08110111 October 2011  15 An enlarged view of the TDB830 MP3 module and its method of connection to the underlying PCB. The seven wire connecting links at the right side can be made with resistor lead offcuts (assuming, of course, they’re long enough!). automatically disconnected. A volume control is included on the front panel along with a power switch and power indicator. The SD card The card normally slots into place in a connector directly on the MP3 module. However, this is inside the case and may be at least a little inconvenient to use – especially if you want to swap sounds. So we have made provision for an external SD card, accessed via a slot on the front panel. This requires the addition of a few extra parts including an SD card connector. Having the externally accessible SD card connector does not prevent use of the SD card connector that is on the MP3 module itself but note: only one SD memory card can be used at the one time. At the rear of the Quizzical! are six 3.5mm stereo jack sockets – four for the leads to the contestant pushbuttons, one for the QuizzMaster pushbutton and one for the loudspeaker outlet. Power is via a DC power socket using a 9 or 12VDC plugpack or a 12V battery. It is not recommended to use a small 9V battery to power the Quizzical!, as the battery will be discharged rather quickly. Maximum current drain is about 200mA or so while playing sound at maximum volume, so using a 12V gel cell is perfectly practical and proper! It drops to as low as 45mA on standby. Circuit The Quizzical! is based around a Tenda Electronics TDB380 MP3 Module and a PIC16F88 microcontroller (IC1). The microcontroller is used to monitor the contestant switches (S1-S4) and QuizzMaster (S5) switch and to drive the LEDs associated with each switch. The microcontroller also, operates the MP3 module via a serial connection and monitors the trimpots provided for playback and answer period adjustment. Switches S1 to S5 are monitored via the RB4, RB6, RB1, RB3 and RB0 inputs of IC1 (respectively). The switches and LEDs share a common ground; each of the switches connects to the 3.5mm plug tip while the LEDs connect via the ring. Internal pull-up resistors within IC1 keep the switch inputs at 5V unless a switch is pressed, pulling the input to 0V. Each switch input is bypassed with a 100nF capacitor to prevent noise and interference from falsely triggering an input. Switch contact bounce is not a problem as the microprocessor responds to the very first switch closure and ignores any other switch input – from that switch or any other. Indicator LEDs, LED1 to LED5 associated with each switch are driven from the RA0, RA7, RA6, RB7 and RA4 outputs respectively via suitable series resistors (we’ll have more to say on these shortly). Trimpots VR2 and VR3 connect across the 5V supply and therefore provide a voltage to the AN3 and AN2 inputs ranging between 0 and 5V. The microcontroller converts the voltages into digital values which in turn set the timeout for the answer and play periods. VR2 settings between 0V and about 4.5V provide a play period between 1.3s to 18s respectively. Similarly, VR3 settings between 0V and 4.5V provide an answer period between 1.3s and 35s respectively. The advantage of these timers is that the MP3 file lengths for each sound do not have to be individually edited to set the playing period. Instead the timers handle all play lengths. However, if you want longer periods or if you want different length play periods for each player, then the required trimpot (or both) can be set fully clockwise. This results in 5V at the AN3 and/or AN2 input. Then the The rear panel of the Quizzical! has is a DC power socket (9-12V DC from plugpack or gell cell battery), along with six 3.5mm jack sockets – four for the contestant push-buttons, one for the QuizzMaster push-button and one for the mono external speaker output (which could also be used to connect it to an external amplifier/speaker for some really dynamic sound)! 16  Silicon Chip siliconchip.com.au shorter than about two seconds in length. If a second contestant pushbutton were pressed within a couple of seconds after playing this short file then the second file would not always play. We overcame this quirk by checking the busy signal to find out if the second file has started. Should the second file not begin to play a second or two after the first file has finished, then the ‘play the second file’ command is re-sent. Ceasing play of a file that is two seconds or less in length using the QuizzMaster pushbutton is not always possible with this module. But it is not really a problem as it is only a short file anyway. You will just have to wait it out. The tiny 8 speaker is glued to the case lid after you first drill a series of “sound holes”. Note also the glob of silicone sealant (at left) providing strain relief. MP3 file length sets the timeout period. This period can range from zero seconds to any file length. The TDB380 MP3 Module is controlled by the microcontroller using a serial connection between the transmit (Tx) output of IC1 (pin 11) to the Rx input of the module. Baud rate is 4800bps with 8-bit data and one stop bit. A precise baud rate is not critical and we tested for successful operation with baud rates ranging from 5000bps to 4464bps. With that range of workable baud rate, the microcontroller can run from its internal oscillator that has a nominal 2% tolerance at normal room temperature, rather than having to use a crystal for a more precise baud rate. With serial control any number of files can be selected, from 1 to 199 in any one folder. There are 15 folders available. For our Quizzical! we only use up to six files in each folder and there are five folders that can be accessed. The default folder is folder 1. This is also called the root directory. Sending a play command to the Rx serial input of the module plays a file. Each file is individually selected using a separate serial code. When the module is playing a file, a stop command can be sent to the TDB380 to cease play. Stop has high priority and operates immediately. This is in contrast to sending a file ‘play’ command when a file is already playing. The module will wait until the file has completed before playing the next file. To play a new file before siliconchip.com.au the current file has finished playing, a stop command has to be sent first to stop the current file playing and then the new file command is sent. The busy flag output from the TDB380 module is monitored by the microcontroller’s AN1 input for indication of when a file has finished play. During play, the busy pin is low (close to 0V) while the end of file is indicated with a high (2.2V) signal which indicates the module is not busy. The AN1 input checks if the voltage is above or below the mid point of these two voltage levels. So if voltage is below 1.1V, then the module is busy and if the voltage is above 1.1V then the module is ready (not busy). Monitoring of the busy signal is useful for determining when a file has finished. That information is used by the microcontroller to ensure a contestant cannot play his or her unique sound if another contestant has already pressed their button, starting a file playing. The busy signal also informs the microcontroller when the answer period has expired, when this is set to the file length of the answer period file. For files that are longer than about two seconds, pressing the QuizzMaster switch will cease play immediately. Also another file can be played immediately after the first file has completed by pressing a contestant pushbutton. These are the expected responses from the MP3 player to stop and play commands. The MP3 module has a few quirks that occur when playing MP3 files Audio out Audio signal from the MP3 module is at the left and right channel outputs at pins 18 and 17 respectively. We used two 47 resistors to mix the left and right channels into a mono signal. The mono signal is AC-coupled via a 10F non-polarised capacitor to a 1kvolume control. These resistances are made low in value to minimise induced noise into the audio from the MP3 player as the Player reads the SD memory card. Low-level switching noises in the audio signal would otherwise be evident, especially when using the external SD card connector. Another way we minimise this noise is to use a metal front panel, which connects to Legal issues Strictly speaking, with the exception of sounds you create and record yourself, any sound files you play using the Quizzical! are subject to copyright – especially if you use it in a public place or for example, broadcast a quiz using them. That applies to sounds you download from the web, grabs from CDs, even things like ringtones (which we imagine will be pretty popular on Quizzical!). More information concerning the playing of copyrighted sounds in public, including sampled sounds, can be found in the information sheet G089.pdf from the Australian Copyright Council (copyright.org.au) on Music: DJs. October 2011  17 Parts List – Quizzical Main unit 1 PCB coded 08110111, 115 x 102mm 1 ABS Instrument Case 140 x 110 x 35mm 1 SD memory card 32MB to 8GB (A lower range capacity is all that is required) 1 TENDA TDB380 MP3 module 1 134 x 31 x 1mm sheet of Aluminium for front panel 6 3.5mm PCB mount stereo jack sockets (CON1-CON6) 1 PCB mount DC socket with 2.5mm contact pin (CON7) 1 SPDT PCB mount toggle switch (S6) (Altronics S1421 or equivalent) 1 40mm Mylar 8 speaker 1 DIP18 IC socket 1 knob to suit VR1 3 PC stakes 4 M3 x 6mm screws 1 60mm length of 0.7mm tinned copper wire 1 150mm length of hookup wire Semiconductors 1 PIC16F88-I/P microcontroller (IC1) programmed with 0811011A.hex 1 LM386N 1W amplifier (IC2) 1 7805T 5V three terminal regulator (REG1) 1 1N4004 1A diode (D1) 1 3mm green LED (LED6) Capacitors 1 470F 16V PC electrolytic 3 100F 16V PC electrolytic 1 10F 16V PC electrolytic 1 10F NP electrolytic 7 100nF MKT polyester 1 47nF MKT polyester Resistors (0.25W, 1%) 1 10k 1 2.2k 5 330/68* 2 47 1 10 (* see text) 2 10k horizontal mount miniature trimpots (VR2, VR3) 1 16mm 1klog potentiometer with two nuts (VR1) Externally accessible SD Card option 1 SD memory card holder (Altronics P5722 or equivalent) 1 7-way wire wrap socket strip 1 120mm length of 0.5mm tinned copper wire 18  Silicon Chip Quizzical! Specifications Power supply:....................... 9 to 12VDC at up to 250mA. Standby current 60mA. Loudspeaker power:.............. Typically 0.4W into 4 and 8 Contestant sound play: ........ 1.3s to 18s (or sound file length) Answer sound play: .............. 1.3s to 35s (or sound file length) File type:................................ Plays MP3 files (only) with standard bit rates              ranging from 32kb/s to 320kb/s. Memory card:....................... 32MB to 8GB SD card using FAT16 or FAT32 Folders:................................. Up to 5 folders accessible with six MP3 files per folder the volume pot body and circuit earth and forms a shield. Using the 1k volume potentiometer, bass response is rolled off due to 1F audio coupling capacitors in the left and right channel outputs on the MP3 module itself. If you require more lower frequency bass, then the potentiometer should be replaced with a 10k log pot instead (at the risk of more noise). Following the volume control, signal is coupled via a 100nF capacitor into an LM386N amplifier, IC2. This drives a loudspeaker via a 470F coupling capacitor. Supply bypassing for IC2 is with a 100F capacitor across the 11.4V supply and the 10F capacitor at pin 7. The 10 resistor and 47nF capacitor connected in series at the pin 5 output prevent high frequency oscillation when an inductive load such as a loudspeaker is connected. Power Power for the Quizzical! is from a 9V or 12VDC plugpack or from a 12V battery. Diode D1 provides reverse polarity protection for the circuit and switch S6 applies power with indication by LED6. The 11.4V (or 8.4V with a 9V supply) is applied to the REG1 input, the TDB380 module supply pin and the pin 6 supply pin for IC2. REG1 supplies 5V for IC1. The supply is bypassed with a 100F capacitor and 100nF capacitor. IC1 includes a power on reset using the 10k resistor at the MCLR input (pin 4) to the 5V supply. Note that while the TDB380 MP3 Module is powered from 11.4V, an integral regulator reduces the voltage to around 3.3V for the on-board ICs and SD memory card. Other considerations for the mismatched supply voltage are when monitoring outputs from the MP3 module. A high level output from the module can only reach a maximum of 3.3V and this may not be recognised as a high by the microcontroller running from 5V. In our circuit we use an analog input for monitoring the busy signal and so we can set the high threshold to a more suitable voltage as discussed earlier. When power is applied to the Quizzical! circuit, it takes a few seconds before the MP3 module becomes functional. This period is indicated by LED1 through to LED5 all lighting up. When the LEDs are extinguished, the MP3 module is sent a serial command that sets the volume at its maximum level. This volume is an internal digital volume control, not the external VR1 control. The Quizzical! is then ready to operate. Construction The Quizzical! is constructed using a PCB coded 08110111 and measuring 115 x 102mm. The MP3 module mounts directly onto this PCB. The assembled PCB is housed in an ABS instrument case measuring 140 x 110 x 35mm. Begin construction by checking the PCB for shorts between tracks and pads, missing holes and for correct hole sizes. Make repairs as necessary. If you intend to use the externally accessible SD memory card socket, this is installed on the underside of the PCB. Solder the 13 pins at the rear of the connector and the two pins at the front of the connector to the PCB pads. Take care that the 13 pins do not have any solder shorting bridges between them. (These can be cleared with solder wick and a soldering iron to draw off any excess solder between pins). Install the low profile components first. These are the wire link, the resistors and diode D1. When installing the resistors, use a multimeter to check the resistance value. Diode D1 must be oriented correctly. IC1 is installed using an 18-pin siliconchip.com.au DIL IC socket but IC2 can be directly installed on the PCB. Make sure the IC socket and IC2 are oriented correctly. Leave IC1 out of its socket at the present. CON1 to CON6, 3.5mm jack sockets, can be installed now as well as CON7, the DC socket. The three PC stakes can be installed with two located behind CON6 and one adjacent to VR1. The MP3 module has a 20-way right angle header along one side for external connections. The right angle in each pin needs to be bent straight so that the module can be installed horizontally onto the PCB. Carefully bend each pin using pliers so that each pin is fully straightened. Insert the module pins into the PCB holes with the module sitting about 10mm above the PCB surface. Solder the pins to the PCB. The capacitors, regulator and switch (S6) can be mounted now. Make sure the polarised electrolytic capacitors are mounted with the shown polarity. The 10F NP capacitor can go in either way. REG1 is mounted with the metal tab toward the front of the PCB. It doesn’t need a heatsink. Fit the trimpots (VR2 and VR3) now. If the potentiometer (VR1) supplied has a normal-length shaft it will require cutting to 10mm overall length. The pot body also needs to be connected to the PC stake located adjacent to it. This is done using a short length of tinned copper wire (eg, a resistor lead cut-off). To allow solder to adhere to the outside of the pot body, a small area (ie, immediately around where it is to be soldered) normally needs to be scraped off just before soldering the wire in place. LED6, the “power” LED, is mounted with the anode (longer lead) closest to VR1 and with the leads bent at right angles 5mm back from the LED body. The LED is positioned at the same height above the PCB as the S1 switch ferrule. LAST FEW: $AVE $$$ TV ACROSS AUSTRALIA Your easy ref reference ference gui guide ide tto oT TV V recept reception tion across A Australia usttraliia Travelling around Oz? Want to know where to aim your antenna? This book will tell you! Lists channels, location and polarity of all analog transmitters and translators (digital services are usually co-sited). A MUST-HAVE with loads of other TV-related data too! Even if you aren’t travelling, this is highly useful in troubleshooting local TV reception problems. All this information in one handy source! Buy direct fromWhile SILICON CHIP bookshop stocks last: $ RRP: 39 95 29 $ External SD card socket The externally-accessible SD card holder (if used), needs to be connected to the MP3 module via a 7-way IDC socket strip and wire links (see photo). Install the 7-way IDC socket strip alongside the MP3 module. This socket strip is placed so that it sits 10mm above the PCB. Seven lengths of 0.5mm tinned copper wire, each 17mm long, then connect the MP3 module to the 7-way socket strip. Make a right-angle bend at 5mm along each wire length. Insert the short ends of each wire into each socket strip hole and position each wire to sit over the solder pads that connect to the seven used pins of the SD card holder on the MP3 module. Carefully solder each wire to the MP3 PCB. 95 +p&p SEE P85 for handy order form Note that there is more than one version of this MP3 module currently available. We originally designed the Quiz Game using version 1 (V1.0) of the module. This version had the SD card positioned to the far right and the wires from the socket strip needed to solder directly to the pins on the module’s SD card holder. The MP3 module shown in the photographs is version 8.3 (V8.3) and has the SD card holder located centrally on the MP3 module. This has PCB pads available that allow connection to the SD card connector pins without resorting to soldering directly to the connector pins. There may be other versions being sold – which one you have with will depend on the supplier of the MP3 Resistor Colour Codes o o EITHER o OR * o o (*see text) o siliconchip.com.au No. 1 1 5 5 2 1 Value 10kΩ 2.2kΩ 330Ω 68Ω 47Ω 10Ω 4-Band Code (1%) brown black orange brown red red red brown orange orange brown brown blue grey black brown yellow violet black brown brown black black brown 5-Band Code (1%) brown black black red brown red red black brown brown orange orange black black brown blue grey black gold brown yellow violet black gold brown brown black black gold brown October 2011  19 Placing and arranging Quizzical! sound files onto the SD memory card The final part of building the Quizzical! is to acquire and place MP3 files onto the SD memory card. This needs to be done using a computer. Most computers these days have SD card readers installed (or perhaps MMC card readers; for our purposes they are identical). Modern printers and monitors often have an SD slot that enables reading the SD memory when connected to the computer. Failing this, external USB SD card readers (which invariably are also writers) are available for just a couple of dollars. The SD card should already be formatted with either the FAT16 or FAT32 file system. If it is not formatted, this can be done using the format facility on your computer. Files The Quizzical! requires six sound files per folder. Four files are for the four contestants sounds, the fifth one is for the answerperiod sound and the final file is for the end of answer-period sound. The answer-period and end of answer-period files can either be files that produce a sound when played or they can be silent files where no sound is heard. It is important that six files are placed in each folder. One of five folders can be selected when using the Quizzical!. That means that you can have five separate themes for the Quizzical! sounds with one theme per folder. It is not necessary to use all folders and a basic setup will only require six files if access to the other folders is not required. A maximum of 30 files will be needed, when all folders are used. Folders are selected on the Quizzical! itself using the four contestant pushbuttons (S1-S4) and the QuizzMaster pushbutton, S5. To set a new folder from 1 to 5, press a switch (S1-S5) when the Quizzical! is powered up. The associated LED for the pressed switch will flash until the switch is released. The flashing indicates the new folder is now set. If no switch is pressed during power up, the folder remains at the last used folder. The player module used in the Quizzical! will only play MP3 types – you’ll recognise them by the .mp3 at the end of the file name. MP3 bit rates ranging from 32kb/s to 320kb/s and including variable bit rate (VBR) are suitable. Other file types of files such as .wav and .m4p will have to be converted to MP3 format before they can be used with the Quizzical! Where do you get them? Audio files for your Quizzical! are easily obtainable from sources such as CDs and downloads from the Internet. Files from the CD can be ripped and imported as MP3 files. Files from the Internet ideally should be either ones that are purchased or free of charge and royalty free. For more detail see the section entitled Legal Issues. Files can be edited for length and for content within the file, so when looking for suitable files do not be put off because the file is too large. If it contains a section you wish to use then this can be selected and made into a shorter file. It is important that the file plays immediately, ie, there is no “dead air” at the start of the MP3 file. Any “dead air” can be edited out with a variety of sound file editors. Files that are already short may be directly suited for contestant and end of answer-period files. The time periods these files are played are set by the play period adjustment using VR2 or by file length. Up to 16s play period is available via the VR2 setting or this can be set longer as set by file length. A file for the answer period needs to be long enough to give contestants “thinking” time as well as answering time. The answer period can be set (using VR3) for up to 35s or by file length. So if you want a longer than 35s period, then the file needs to be longer at the required timeout length. If you prefer not to have sound during the answer-period, then a silent file can be used. Sound files are commonly available on the Internet and a good list of sites is available at www.teachers.ash.org.au/suel/freestuff/ sounds.html Music files are available from download sites such as iTUNES at www.apple.com/au/itunes/ Special interest sites for audio files include ones for the Looney Tunes cartoons at www. nonstick.com/sounds/; Monty Python at www.intriguing.com/mp/ sounds.php; Science fiction at http://itunes.apple.com/au/artist/ science-fiction-sounds/id169052199 and general sounds at www. soundjay.com If the files can be downloaded as MP3 types then this will save having to convert the files. But if a file is only available in wave format, it is not difficult to convert the file. .m4p files Files with a .m4p suffix are not as easily converted to MP3 format as they are AAC protected files (MPEG-4 protected Advanced Audio Coding audio files). Most of the files that are downloaded using iTUNES are .m4p files. You could purchase a commercial m4p to mp3 converter (such as available from www.m4p-mp3.com) or alternatively, a relatively inexpensive way when only a few files are to be converted is to first make a CD of the .m4p files you wish to use. This can be done in iTunes where the required files are placed on a playlist. The CD is burnt as an audio CD rather than as a data disc. You can use mono or stereo MP3 files as the stereo output is mixed into a mono signal. File handling Audacity can be downloaded from the net (http:// audacity.soundforge.net/download/) and is perfect for editing and converting Quizzical! file formats if a suitable MP3 codec (eg lame_enc.dll) is first loaded (eg from http://lame.buanzo.com.ar/). 20  Silicon Chip Once you have the necessary MP3 files for your Quizzical! you may wish to edit them. Editing can improve the sound file by having the relevant section of the file start as soon as the file is played and you can set the file length. siliconchip.com.au File editing can be done in Audacity. The start and end position of a file can be selected by wiping over the required file section with the mouse cursor and exporting the selection as an MP3 file. Editing allows a file to start exactly at the sound point you require. It can also select when you wish the file to end. Additionally, it may be worthwhile normalising or compressing each file. Normalising sets the effective volume of the file to a standard level, while compression reduces higher volume levels reducing the overall dynamic range. With these processes, each file will have a similar sound level when played. To do this, select the file and Effect/Normalise or Compressor. Other Effects that you might wish to use is to change the pitch, speed or tempo, reverse the file or add in echo. These features are also available under the Effects tab. Two screengrabs showing the difference between an unsorted file list (above) and the same files having been sorted into correct order (below). Creating a silent file When you wish to play silence rather than a sound for the Quizzical!, you will need to have an MP3 file that has no sound. To create a silent MP3 file, first open a new file (file, new) then select Generate/Silence. Type in the desired length (in seconds) then click OK. Placing files onto the SD card The SD card needs to have each set of six sound files placed in separate folders. The first folder is the root directory (folder1). This folder is not named but it is assumed to be the 01 directory. It should contain the first set of four contestant files; the answer-period sound file and the end of answer period sound file totalling six files. For the Quizzical! to work correctly, these six files must be present. Files can be silent if required but a missing file cannot be used in place of a silent file. Another set of six files can be placed in folder2. You can create up to five folders. Folders should be named 02, 03, 04 and 05. The first folder is the root directory where the first six files are placed. In the accompanying screen shot, (see SD Folders screenshot below) we show .mp3 files named from 1.mp3 to 6.mp3 in the root directory plus the other four folders. One thing to note is the order that the Quizzical! plays the files. The first four files (1 to 4) should be the contestant sound files. The next file (5.mp3) should be the answer-period file and the end of answerperiod file is 6.mp3. This is straightforward – but there is a trap. On a computer you can arrange files in order based on alphabetical order, file size, file type etc but this is not so with the MP3 player module. The module plays files in the order that they are arranged on the file allocation table (FAT). This is a limitation of the file handling ability of the MP3 player. The file arrangement on the FAT is not necessarily the same order that the files are seen on the directory when viewed using a computer. Screen grab of our “SD Folders” with files ready for use by Quizzical! Note the order and naming is important – it’s explained in the text. siliconchip.com.au The simplest way to get the file order correct is to start with a blank folder and then copy the files onto it one at a time, in the order required. This operation must also be applied to folder creation, ie, they must be created in numerical order. However, there may be some situations in which this approach can fail. Another method is more certain to ensure correct file order when the Quizzical! operates. Files are renamed in each folder to 1.mp3 to 6.mp3 corresponding to players 1-4 and 5.mp3 for the answer-period file and 6.mp3 as the end of answer-period file. A file sorting utility is then used to rearrange the FAT to correspond to the file numbering. For more detail on this file order problem see www.anerty.net/ software/file/DriveSort.php. You can also download the Drive Sort utility from this site and the ‘download file’ button is at the bottom the page at that site. Once the file has downloaded, open the zip file; extract the files and place onto a suitable directory (folder) on your computer hard drive. Run the DriveSort.exe file. Once the utility is running, select Disk open (see left) and open the SD memory card. Select the folders and the contained files will be shown, in the order arranged by the FAT. Note that the files are not necessarily in numerical order. To order the files, Select: Order/Ascending and then Folder/Sort. Folders will be sorted in ascending order. Then select Folder/Save to save this file order. Repeat for all folders including those at the root directory. This also sorts the folders in order. Select Disk/close to exit the program. The “Drive Sort” utility downloaded from www.anerty.com (see text). October 2011  21 module and how much stock they have of a particular version. Enclosure Work can now begin on the enclosure. It’s a two-part box and you will find that the two halves only go together one way. Front and rear panels are separate and, as mentioned earlier, an aluminium panel is substituted for the plastic front panel supplied. Holes are required for the power switch, LED and potentiometer on the front panel and for the 3.5mm jack sockets and DC socket on the rear panel. Hole positions and hole sizes are shown in the panel artwork (downloadable from siliconchip.com.au) with hole positions and sizes shown. When the externally accessible SD memory card holder is used, a slot is also required on the front panel. The outline for this cut-out is shown on the front panel artwork. The small loudspeaker is positioned inside the top lid toward the rear of the box. Holes are drilled through the lid over the loudspeaker cone area (before the speaker is glued in!) We used neutral cure silicone sealant, although many other types of glues are suitable including hot melt, contact adhesive and other plastics glues. Simply run a in the case. The PCB and panels are secured in the bottom half of the case with four M3 screws that screw into the four corner posts of the box. There are extra R = “RING” mounting posts in the case that foul T = “TIP” CABLE LENGTHS (CONNECTS TO (CONNECTS TO the PCB, preventing it from sitting flat. TO SUIT LED ANODE[S]) SWITCH) CONTESTANTS These can be removed by twisting off using pliers. Finally, the speaker is LED ANODE IS SWITCH LONGER LEAD NOT K wired to the PCB loudspeaker PC A POLARISED stakes using hookup wire. A dollop of glue can be used to hold the CABLE BRAID = SOLDER speaker wires to the case lid, removing any stress on the soldered joins. Fig.3: here’s how to wire each of the S = “SLEEVE” (CONNECTS TO LED CATHODE[S] AND SWITCH COMMON) contestant and Quizzmaster pushbuttons to the 3.5mm plugs. thin bead of glue around the speaker edge and allow it to dry. The front and rear panel labels, which are glued to the panels, can be printed onto paper, photo paper, film or similar and glued to the panel. Cut the holes out with a sharp craft knife or leather punch. The finished panels are attached to the front and rear of the PCB with the nuts for the 3.5mm sockets securing the rear panel and the pot nuts securing the front panel. We used two nuts on the pot, one behind the panel and the other on the front of the panel. The rear nut is to space the panel from the pot so the panel is positioned correctly Testing With all four player and single QuizzMaster pushbutton units plugged in, apply power and switch on with S1. Check that LEDs 1-5 light for a few seconds after powering up. The power LED (LED6) should remain lit. Measure the voltage between pins 5 and 14 of the IC1 socket. This voltage should be close to 5V. If the voltage is outside the range of 4.85 to 5.15V, then check for a possible short circuit across the 5V supply. Also check that there is voltage at the input to REG1. When the 5V supply is correct, switch off power and insert IC1. Further testing can be done after the SD card is written with MP3 files. TENDA Electronics TDB380 MP3 player module Measuring 51 x 33 x 8mm, the MP3 player can be used as a music player, a sampler sound box, doorbell, announcer and many other similar applications requiring sound. The module operates from between 6V and 24V at up to 100mA and plays MP3 files that are stored on an SD memory card. Up to 199 MP3 files can be accessed on each of 15 folders for a total of 2985 files. Sound output is in stereo at up to 200mVp-p at the output. This output can drive headphones directly, although it will be a low level and the 1F on board coupling capacitors will roll off the bass. There are four ways that the module can be used. Two methods simply have switches attached to the inputs to allow playing of the various files on the memory. For the MP3 player mode, switches allow the module to operate as a normal player. In this mode it has volume, play, pause, stop, previous, next, fast forward and reverse, plus change memory folder (directory) functions. The second switch-operated mode allows independent selection of up to eight files. Volume and random play are also available. This mode is ideal for doorbell, robot sounds, announcements etc. The remaining two modes require a computer or microcontroller to drive the MP3 module via parallel or serial data connection. Each mode is selected by setting two solder link connections as either open or closed. For the serial mode, this will 22  Silicon Chip operate with any jumper link setting. The data sheet for the TDB380 module is available from www.thaieasyelec.net/archives/Manual/TDB380%20 datasheet%20V2%5B1%5D.0%20.pdf The MP3 module is manufactured by Tenda Electronics (www.tendaelectronics.com) and is based around a Shanghai Mountain View Silicon Technology AU6850 MP3 decoder. Some of its features include: • SD/MMC card reader controller • Supports MP3 (MPEG 1/2/2.5 layer-III decoder) at 32320kbps and Variable Bit Rate • Supports 9 sampling frequencies: 8kHz, 11.025kHz, 12kHz, 16kHz, 22.05kHz, 24kHz, 32kHz, 44.1kHz and 48kHz • Supports FAT16 and FAT32 file systems • Embedded 16-bit sigma-delta audio DAC • Embedded headphone amplifier The module is available from the USA at www.mdfly.com/ for approximately $16.00 inc postage. You could also try Rictech in Melbourne (graeme.rixon<at>yahoo.com). Failing that, Tenda Electronics do sell direct to the public as “samples” but their website doesn’t have a shopfront: you have to do it all by email and Paypal. Also watch the one-off freight charges – they can be very steep (eg, four times the unit price!). siliconchip.com.au THE “EASY” PUSH-BUTTONS When we first developed this project, we used ordinary push-button switches mounted with a high-brightness LED in a small translucent jiffy box. Now there is nothing wrong with this approach but having watched QI and TAYG many times, we thought they were a little underwhelming. We wanted a PUSH-BUTTON, not a Player and QuizzMaster switch and indicator PUSH-BUTTON. Admittedly, this approach is probably a bit easier so we’ll show it here, along with its parts list, for those who want to go this route. It’s not at all critical where the pushbutton goes (but logic suggests the centre) and as it and the LED share a common (-) connection, the LED could simply have its cathode soldered to this point. (Uses 330resistor on PCB) 5 UB5 (83 x 54 x 31mm) clear boxes (eg, Jaycar HB-6015, H0205) 5 SP momentary push button switches (S1-S5) (Altronics S1080, Jaycar SP0716) 5 5mm high intensity LEDs 5 5mm LED panel clips 5 cable glands for 3mm cable 5 stereo 3.5mm jack plugs 2-core screened cable (length to suit installation) THE “PRO” PUSH-BUTTONS We went searching for the large push buttons as used on those shows and yes, they were available but no, they were FAR too expensive. That’s when we started thinking “outside the square” (OK, I was taking a walk through my “other home” – Bunnings) and I came across the small (100mm) battery-operated LED lights pictured here. They’re sold as either push lights or night lights, depending where you shop. Brand is “Magic Living”; (Bunnings barcode 9337897 001 942). The price was certainly right – about $7 for two! – but the only problem was they had push-on, push-off switches. We needed momentary. I also spotted a larger version of the same thing, with somewhat similar electronics, which would be perfect for the “QuizzMaster” controller. After disassembling one of these to see if I could get the switch apart easily and convert it to momentary, I quickly gave up that idea. Too small, too flimsy (although if you want to give it a go, be my guest. Nothing ventured and all that!) So I thought “what about fitting a different switch?” The biggest problem here was that the moulding suited the fitted switch and nothing else that I could find would go close. The other difficulty was that the travel in the switch had to be pretty well spot-on. After various measurements and tests, I bought a couple of tiny momentary switches from Jaycar (SP-0603) and glued them in place using JB Weld. While that was drying I turned my attention to the LEDs. There are three of them, all white high-brightness types, mounted in parallel on a small PCB, along with a tiny inverter to step up the 3V from the two “AA” cells to give enough to light the LEDs. As the PIC outputs 5V, I knew I didn’t need the inverter so I whipped it out and tested the whole thing out on a 5V supply. Voila! The 330 resistor specified in the original circuit is much too high to get the required brightness so I replaced it with a 68, which limits the current to safe levels for Remove the four screws (carefully!) to reveal the 3-LED PCB and switch. Prise out the switch and glue a mini momentary type switch (eg Jaycar SP-0603) in its place. Make sure the height of the new switch actuator is the same as the original switch. Also prise out the LED PCB and unsolder the two components (arrowed) – they are not required. siliconchip.com.au the PIC output. And that is how we ended up with our “pro” contestant push buttons. A length of two-wire shielded cable, exactly as per original, was soldered to the PCB and run out through the now-vacant battery area. The 150mm light has a 6V supply (4xAA cells) so therefore has no inverter. But you will need to remove its internal resistor, change the switch to momentary and run it as above SC from the PIC and 68resistor. Wire a suitable length of shielded two-wire cable to the LED PCB and the switch. They share a common earth. Reassemble the light (don’t lose the tiny springs or screws. . .) and you’re ready for action. Repeat for the other four push-button lights. October 2011  23