WTV020-SD Regular SD Card hack

I ordered a WTV020-SD audio player module from eBay for an MP3-player doorbell project.  These modules support an MP3-player mode, but do not play regular MP3 files. MP3 player mode just seems to hint at being able to play/pause/skip tracks on the micro-SD card. Furthermore these modules are very picky about the micro-SD cards used. I found exactly one Sandisk 2Gb card which plays correctly, all others tested don't play at all...
As I planned to build multiple wireless doorbell nodes I needed more supported micro-SD cards.
After google'ing around it appeared I wasn't alone in the quest for micro-SD cards supported by this little player. Most reports of cards working were for relatively small cards of 1Gb or less, but I didn't plan on buying a batch of overprized micro-SD cards at random, hoping they would play in the WTV020-SD module.

SD cards to the rescue

Going through my collection of SD cards I found out I had quite a lot of small-capacity regular SD cards lying around.

So I heated my soldering iron and attached a modified male header to function as SD card connector.

DIY SD card connector soldered to the WTV020-SD

Close-up of the WTV020-SD

First I tried the supported 2Gb Sandisk using a SD to micro-SD adapter and voila, it worked!

Now I wrote a few audio tracks to all of the smaller SD cards and inserted them in the DIY SD card adapter one-by-one. Below are all the cards in my collection which appeared to work correctly with the sound module:

Regular SD Cards found working with the WTV020-SD

Especially the Platinum cards are interesting. I once bought 3 of them simultaneously, but only 2 work correctly with the sound module... This once more confirms the hocus pocus going on in this module!