I just used one of them with a speed control I knocked up using TIP31C a 5k pot and 3v battery and it won the day. My friend had a project going linked to his 3d printer. I was asked to get a turntable he had that was surrounded by leds giving much too much brightness to my mind, running almost stopped, as he said he needed it.
I had it running a one rev per minute and every time I turned that pot lower it stopped dead on me. Try as I could it would not run so low as to turn that turntable slower and my suggestion of it being belt driven so when the motor turned five turns the table turned one, meaning he could go slower he refused that idea. 
He eventually took it away to try out and came back grinning. Whatever it was doing the one rev per min worked so it was smiles and beers all round.
If you have any ideas why that motor refused to go slower than one rev per min I would be grateful.
BFN
petyoung
