I haven’t really done any work on the dryer at all, none of the software is done and all I did was test that the new dual channel humidity and temperature sensing would work. By the way to do the dual channel I had to use a quad analogue switch to switch the I2C since the ebay sensors I’ve got don’t allow a choice of the I2C address.

What I have been doing is designing a PCB for the controller part, and tonight I sent if of to Seeed Studio to get fabbed. This cost me just over $20 Australian, although I have to wait from between 15 – 30 days for the boards to arrive (I get 10 although I doubt I will ever use more than one). I am quite nervous that the fab will fail or that my design can’t be fabbed, or, of course that I haven’t transcribed the circuit from my hand wired version.

Kikad takes a little bit to get used to but it wasn’t that difficult to design this board; not that it’s a very big board. The last time I had a board I designed made I had to lay it out with black tape, I hardly recall, but it must have been painful. Although neither method is as painful as doing point to point wiring, even at this small scale. I’ve done a board with point to point soldered connections using wire wrap wire, where each end needs to be stripped, that had hundreds of connections. I can’t believe I did it now. That was the graphics terminal, I wish I still had it, I would frame it an put it on the wall.

How the design looks in Kikad.

This is the board in the gerber viewer.

I am not motivated at present to do much else at the moment even though I have had some good ideas about the software; once I can measure the ambient humidity then I think I can make the thing work more sensibly. I have again found that clothes that are hung on the line still dry faster and clothes dryed in the dryer sometimes have a faint smell about them. I think it depends on how much sun is available. I really need to design and build the new air extracting chimney hat and of course create at least version 2 of the software ( to control the fan by comparing inside and outside humidity ).

Just awaiting my board now.