I've heard most people advise against those spring based belt tensioners, they basically introduce another stretchy element to the belt. Haven't had any experience with them myself so I don't know how true it is. The Zatsit is a neat bit of kit, I'd be interested to see how long the living hinges hold up, but it's really beautiful in its simplicity.Also for the third time, I never said to use PWM with a coil relay, I suggested bang-bang control. Aardvark, I'm trying, but he takes half of my first sentence and then jumps to conclusions, or skips over the rest of my post where I mention the stuff he complains about. Or just makes things up like the PWM on a solenoid relay.