The solid state relays have arrived from Thailand of all places. I have the therapy of wiring them up, realizing that they don't work under load, which is a shame as I want them to drive a load. Quickly you see there is no easy symmetry for them to drive a DC load and a look on the internet you require an H bridge which I had wired up many years ago to drive stepper motors. Thus time to order DC motor controllers, this time $18 rather than $8. There is interest from the Universities about me making an automated titration station and I discuss a safe approach to this. MP4 recording     MP3 recording -- -- Your browser does not support the audio element.