It was suggested to me that what this site really needs is a relay board, so here it is.
I didn't bother with a circuit diagram as the layout is
rather straightforward. There are thee relays - in this case I picked the
6V type. Each relay has two change-over switches. These are connected to the three terminal strips closest to their
There is an LED in parallel with each relay because when developing a program, it is often useful to see what the
relays are doing without having to connect anything to them.
There are three diodes to take care of the back emfs of the relays.
Strictly speaking, these aren't necessary as the Darlington drivers used
with the Velleman board - as well as my interface board - have built-in back emf diodes. I
included them just in case the unit gets connected to some other - non-protected -
There is a fairly wide bare PCB space between the low voltage
and output voltage parts of the board. So as long as one uses suitable
PCB material, mains operation should be no problem.
The PCB layout - as seen looking through the board - can be admired below.
Below are three files which might be useful.