Hi! This sounds fun! ^^

The rare Covox Sound Master had got an AY-3-8930 tone generator,
so even for the sake of completeness alone,
it would make sense to have got an AY dongle, too.

Covox Sound Master Reverse Engineering / Replica

I'm aware of the Covox Sound Master, but I think I'll settle on a CPC-style circuit, instead. The CPCs were quite a bit more common.

In that case, the AY-chip runs at 1 MHz and a network of resistors combines the three output channels to a stereo signal.
The stereo output on the AY-LPT dongle could then either use that directly or add an emitter follower and/or single-transistor amplifier with or without volume wheel.

I found several schematics for an AY-LPT device used for example in ZX Spectrum emulation. Maybe this is of intrest for you:

LPT-AY by Vitaly Mayatskih & Alexander Kulik
LPT-YM by Romanich
AY-LPT by Jarek Adamski for ZX Spectrum and Timex Computer
Infos by tronix286
Infos by krssh

USB-AY by tronix286 and on vcfed

Oh, thanks!
The first one looks roughly similar to what I had in mind.
Maybe I can make compact dongle that is fully compatible on the software side.

It's been a while, but now there is some progress:

The design contains a micro USB socket for power, a volume wheel, a 1 MHz oscillator IC and a bunch of 100Ω resistors to limit the current flow into the AY-3-8913's input pins when the chip is not powered, but is largely compatible with the one in aylpt.txt
The socketed AY-3-8913 inside a normal parallel port dongle enclosure is going to be a tight fit, but thanks to the creative positioning of the PCB it will fit.

@Benedik: That looks pretty cool. Using the AY-3-8913 instead of the AY-3-8910 is a good call.

I also made a AY-LPT prototype recently based on the schematics by Tronix: https://dosreloaded.de/forum/index.php?thread … rk-in-progress/

A new version (see attachement) has been ordered an should be on its way. This version can be jumpered to work either with the ZX-speccy Emulators or with some AY/YM players (at least under DOS).

I have build my second prototype. The oscillator circuit is a bit picky but otherwise it works.

https://www.youtube.com/watch?v=-JZ7SJhLblo
https://www.youtube.com/watch?v=p0Y09cNXOKo

I am planning one last version that can be jumpered to 2.0, 1.79 and 1.0 MHz clock input. Furthermore, there will be a simple switch to change between Modus 1 and 2 for software compatability. I also have added footprints for AY-3-8912 and AY-3-8913 chips.

@Benedikt: The AY-3-8913 has "chip select" on pin 24. This function is absent from other AY and clone chips. Can you leave that one unconnected on the PCB or do you have to control it via the LPT-port for the chip to work?

LordMortiferus wrote on 2023-02-21, 14:39:

@Benedikt: The AY-3-8913 has "chip select" on pin 24. This function is absent from other AY and clone chips. Can you leave that one unconnected on the PCB or do you have to control it via the LPT-port for the chip to work?

The chip only responds to CPU access when pin 24 is low. The datasheet claims that the pin has an internal pull-down resistor, so that if you leave it unconnected, it will always be low. So, leaving the pin unconnected is fine.