I don't know anything about that board, I have never seen it before. Unfortunately, it seems that sellers don't know anything about it either. They claim it runs on 3.3v but there is a terminal clearly marked 5.0 and there is only one conclusion you can draw about that. I think it's a fair bet that it runs on both 3.3 and 5v - something one would think the sellers would trumpet loud and clear for all to hear, but they don't even know what bluetooth module it is. It is clearly an HC-0 something but you will never know what, until you test it.
For all that dark mystery, I would be inclined to buy it. You probably don't need an HC-05, so if it's an HC-06, which I think is likely, it is OK. It won't be any more unsuitable than what you've got.
.........And yes, the HC-0x
modules are 3.3v devices but note that the JY-MCU package has all the level shifters on
board and is clearly labelled for 3.6 to 6v operation. If your Arduino is made for 3.3v
operation, read no further. "
I'm really glad you are reading what I have written, particularly as this bit is in a state of flux, somewhat. More to the point, it appears that you are one of the gang the is moving the goalposts, and I am struggling to keep up.
Note that I refer to the JY-MCU.
Yes, the JY-MCU is clearly labelled for a 3.6 to 6v power supply, and yes, you shouldn't have much faith if you are only feeding it 3.3v. Nobody can doubt the theory but the practice may be different.
It is now clear that I was wrong to say that all the levels are fixed on the JY-MCU board. The Tx-Rx pins are marked for 3.3v operation. Don't ask why they would only do half the job. There are varying views on all of this, mine is to ignore it all. A better view is that Arduino doesn't care, so don't worry about the Rx, but Bluetooth is inherently 3.3v and might get uptight about 5v leaned against its Rx pin, so regulating Arduino's Tx to 3.3v is a good idea. I still have not done this but it would be irresponsible not to mention it, and I update that PDF pretty regularly.
Which might imply, that it just doesnt work, when the Pro Mini runs on 3.3v.?.
Well, I'm sure you can't rely on it but there is a similar thread herehttp://forum.arduino.cc/index.php?topic=224113.msg1627838#msg1627838
where I reckoned the power was suss, and I was wrong - for now.
I tried applying 4.5v through RAW, but still nothing.
As I understand it the RAW input allows you to put 4.5v through the Pro Mini's on-board regulator. I therefore assume you are feeding the same 4.5v to Bluetooth, and that should work - providing there is adequate current.