Path: ns-mx!uunet!cis.ohio-state.edu!sei.cmu.edu!fs7.ece.cmu.edu!crabapple.srv.cs.cmu.edu!andrew.cmu.edu!sk2f+ From: sk2f+@andrew.cmu.edu (Seth D. Kadesh) Newsgroups: comp.sys.apple2 Subject: stereo schematics! Message-ID: Date: 11 Sep 91 03:23:39 GMT Organization: Carnegie Mellon, Pittsburgh, PA Lines: 173 Below is a copy of the posting made which contains a quad sound decoder. From: Keen Jeffrey Alfred Organization: University of Alberta, Edmonton, Alberta, Canada Subject: GS quadrophonic sound We all know that is S in GS stands for sound. Stereo cards abound but the GS is capable of much more. The following circuit uses the same technique as stereo cards to decode stereo but decodes quadrophonic. Inside the GS by the memory expansion slot exists the sound expansion connector that most stereo cards use. The pin outs are as follows: 1 Analog to digital in 2 Analog ground (case ground) 3 Waveform out 4 Channel address zero 5 Channel address one 6 Channel address strobe 7 Channel address two The analog in doesn't consern us here. The waveform out is the important signal. The contains the output of all oscilators one after the other in quick succession (the DOC only handles one at a time). When the DOC is outputing the waveform from an oscilator it puts the channel address from the DOC register $A0 + osc (most significant four bits) on the three channel address lines and pulls the channel address strobe low. (The DOC realy has four lines but only three are connected in the GS). The circuit below uses the first two lines the decode the channels (creating 4 unique channels) and breaks the signal into four parts depending on the address using cmos single position single toggle wired as dual position single toggle switches. Then the chopped output is smoothed with an active low pass filter with a corner frequency of 17.7KHz. Because most programs only use stereo the second channel address in normally low so this circuit will also decode stereo and this will turn up at the front two outputs. I have built this circuit on a bread board but need to make a PC board to make a better sounding circuit. Also the output impedance should be set to 75K ohms but I haven't yet gotten around to it. To purchase all the componets costs about $20 canadian which I feel is not bad considering the price of stereo card (most of which do more like allow digitizing). If anyone has the equipment and time to design and make a PC board I would be interested in hereing how it go's. Please forgive the messy apearance of the circuit diagram it not esay drawing these in ascii. To make sound in stereo or quad all you have to do is place the binary address of the channel you wish the sound to have in the control regsister for the ocsilator (the tools can do this) and there you have it. C1 o----||----o |\ 1/4 IC7 | R2 | o-----------o--| >o---o o--/\/\/\--o | | |/ __|___ | _ o-|-----o-----|-------|____|--o _________ R1 | | \_ IC1 | | | __|___ 1/4 IC5 | |output | Pin 3--/\/\/\--o-|- \_ | | | o-|____|------------o----|stage |----FL | \__o | | | 1/4 IC5 |_______| o-|+ _/ | | | |\ 1/4 IC7 | | _/ | o---|-|---o--| >o---o | |_/ | | | | | |/ __|___ _|_ | | o-|---|-------|____|--o _________ /// | | | | __|___ 1/4 IC5 | |output | | | | o-|____|------------o----|stage |----FR IC2 | | | | 1/4 IC5 |_______| ______ | | | | |\ 1/4 IC7 | | | | o-|-|---o--| >o---o Pin 4----|a 1|-------------o | | | | | |/ __|___ Pin 5----|b 2|---------------o | o-|---|-------|____|--o _________ | 3|-----------------o | | __|___ 1/4 IC6 | |output | |__ 4|--------------o | o-|____|------------o----|stage |----BL Pin 6----|EN | | | | 1/4 IC6 |_______| |____| | | | |\ 1/4 IC7 o----|-|---o--| >o---o | | | |/ __|___ o-|---|-------|____|--o _________ | __|___ 1/4 IC6 | |output | o-|____|------------o----|stage |----BR | 1/4 IC6 |_______| | _|_ /// Typical of out output stages. C2 o----||----o | R3 | o--/\/\/\--o o----o | _ | | v | | \_ IC3 | ----o--/\/\/\--o-|- \_ | R7 | \__o--------- o-|+ _/ | | _/ | |_/ _|_ /// R1 - R6 : 1.2k ohm R7 - R10 : 2k ohm trim C1 - C5 : 47pf IC1 : LM318 high speed op-amp IC2 : 74F139N dual 2 to 4 decoder IC3 - IC4 : TL072 dual op-amp jfet input IC5 - IC6 : 4016 cmos SPST analog switch IC7 : 4069 cmos hex inverter ------------------------------------------------ From: brianw@microsoft.UUCP (Brian Willoughby) Newsgroups: comp.sys.apple Subject: Re: GS quadrophonic sound Date: 15 Nov 89 03:08:26 GMT Reply-To: brianw@microsoft.UUCP (Brian Willoughby) Organization: Microsoft Corp., Redmond WA Lines: 29 In article <1989Nov10.175249.9131@alberta.uucp> c326-18@jasper.UUCP (Keen Jeffrey) writes: > We all know that is S in GS stands for sound. Stereo cards abound but >the GS is capable of much more. The following circuit uses the same >technique as stereo cards to decode stereo but decodes quadrophonic. > >IC2 : 74F139N dual 2 to 4 decoder >IC5 - IC6 : 4016 cmos SPST analog switch >IC7 : 4069 cmos hex inverter Keen, While there is nothing *wrong* with your circuit, I thought that I would mention that the functionality of IC2, IC5, 6 & IC7 are combined in a few standard CMOS chips. It turns out that your circuit is so useful in many applications that you can easily find it in one chip, thus saving wiring and lowering noise. Look for a Siliconix DG506 or any make of 4058. I'm not absolutely sure about the number 4058, but just check in any CMOS 4000 series list for an 8-channel to 1 analog multiplexer/demultiplexer (not the digital type, they won't handle audio/sound signals). Happy circuit hacking... Brian Willoughby UUCP: ...!{tikal, sun, uunet, elwood}!microsoft!brianw InterNet: microsoft!brianw@uunet.UU.NET or: microsoft!brianw@Sun.COM Bitnet brianw@microsoft.UUCP ---------------------------end of original stuff-------------- One of the chips Brian refers to is a 4052. Both the LM318 and the 4052 can be purchased from B.G. Micro (cost for both was $3.75 USA) B.G. Micro P.O. Box 280298 Dallas, TX 75228 (214) 271-5546 fax (214) 271-2462 B.G. Micro does NOT supply pin outs for the chips - these must be gotten from their respective manufacturers. I have pin outs buried somewhere on my desk.... The other parts can be purchased from Radio Shack. The schematic I'm working from only does two channel sound. This schematic is found in the book _Inside the Apple IIGS_, by Gary Little. ISBN 0-89588-365-1 The schematic I'm using is similar to the one above, but the resistor values are slightly different. Right now my sound sucks, and I haven't had time to tweak anything yet, but I'll keep everyone posted as I progress..... -seth / everything seems so easy this way but I'm going under sk2f@andrew.cmu.edu / fast, I'm slipping away, am I so crazy? - Marillion