I bought mine and the accompanying the daughter board from nk electronics.
It's cheap, simple, and works great. Just make sure you change the default device in Mssiah from 8 to 11. (that foxed me for days!)
I am using a power adapter to run it, but I think it is possible to take 5v from the datasette port instead.
Also in retrospect I wish I'd used a small ribbon cable to connect the two boards, rather than placing them on top of one another, as this would have made it a less awkward shape to house, but I was desperate to get it working as soon as possible...