There's no huge need to use foil capacitors but you should definitely use C0G/NP0 ceramics in the analog inputs section, then it is guaranteed there are no issues and you can keep the footprints. Well, in that case I'll use film capacitors. (I can keep the footprints, either way.) My original plan …

Well, as you can see, I'm not using any specific capacitor type, yet. (It's just computer graphics!) Basically, the design uses six 10nF capacitors. Two of them are just buffers that keep the 2.5V reference voltage stable, four are timing capacitors. I figured that the capacitors' exact properties …

As you probably noticed, it is heavily inspired by IBM's Analog Input Card. Compared to the original, I used ceramics capacitors rather than foil capacitors, SIL instead of DIL resistor packs, the two NE556s instead of a single NE558 and shrunk it down to 10cm × 8cm. Amazingly, the two NE556s …

Any interest in something like this? game_control_adapter.png I'm aware that a game port on its own is not a sound card, but game ports spent the better part of their existence on sound cards, so something like this might still be a nice add-on for someone who only has an Adlib. This one is designed …

God we need someone with a tool for making custom brackets. But yeah, looks lovely! ah i already have a solution for that into mind :) Then also make some for the snark barker!! Would slot bracket No. 9204-1 by Keystone Electronics do? ( mouser link ) Keystone Electronics appears to have quite a …

There is no full schematic for the SoundJr, yet, but a partial one in my second post to this thread. The SoundJr appears to use an 11 bit 10kΩ R-2R ladder (8 data lines + 3 control lines) with an additional control line to disable the entire thing. The three most significant bits are transistor- …

No problem! Honestly, I do not expect too many surprises, at this point. The only really important thing I need to know is which of the control lines goes where.

I expect to see at least three more resistors – namely 10kΩ – on the back side of the SoundJr board, that, combined with the three 20kΩ resistors on the front side, extend the R-2R ladder to permit the 8 different volume levels. But we'll see.

Well, it's a good thing then that the internet does not forget, right? He produced a product that had 8 step software volume control, double the frequency range of the Covox Sound Thing, and could directly drive a 32 Ohm pair of headphone due to the integration of a simple amp, and even a sleep-mode …

Would you mind taking some pictures?

I'm still not convinced that there's an amplifier IC in there. It wouldn't surprise me if that slightly bigger PNP transistor in the SoundJr is the amplifier. Also, please note that it draws power from several pins combined.

Strangely, four of the five buttons are connected to a control port (output) pin on the parallel port. I don't know why they connected them like that. That is because the joystick input lines need pull-up resistors and the control lines were originally implemented as open-collector outputs with …

The most interesting feature is its ability to drive headphones without sacrificing quality combined with software-controlled volume. Also, I'd say that the 3mA it claims to consume, drawn from several pins combined, really aren't a lot. BTW.: Cloudschatze, do you still have that device and would …

My intention is to get PCBs and components for about 10 pieces each, just to prove that the designs are error-free and because that is the smallest somewhat economic batch size. I'd then publish the design documents, package some DIY kits to recuperate the cost and leave it at that. For the FTL …

Speaking of the FTL Sound Adapter... That device uses a 25.5kΩ load resistor and I reckon the Speech Thing uses 25.5kΩ, as well. I'm therefore going to use 25.5kΩ for my own replicas ( new thread ). MobyGamer's measurements strongly support this assumption: Well, that was educational: CVX-1 …

Hi everyone! The FTL Sound Adapter is fully documented in the Dungeon Master Encyclopaedia. (See http://dmweb.free.fr/?q=node/1514 , more photos at http://dmweb.free.fr/?q=node/622 .) And the Covox Speech Thing has been fully reverse engineered, as well. (Over in the CVX thread at https://www.vogons …