Back in 2010, [Dave] took a stand. He gave up his dependence on gasoline for his lawn mower, and bought a CubCadet CC500 48V lead acid powered electric lawnmower. Within two years, the batteries had already kicked the bucket. Unwilling to let go, he replaced half of the batteries, but that wasn’t enough. It now took him two charging cycles to mow his lawn once
Enough was enough. He had to replace the whole set — but this time, with LiPo.
As an avid lover of drones, he’s been using LiPo batteries for other things for quite a while. He did some calculations and figured he would only need about 10,000mAh at 48V for a 40 minute run time, which would still be a pretty pricey upgrade. So instead he started with 2 x 22.2V 5,200mAh packs instead ($200). As it turned out, that was more than enough.
The circuitry in the CubCadet was pretty straight forward, so it was almost a drop in replacement, minus the need to use a different charger. He added in a switch to flip between charging and mowing modes to allow him to use the LiPo charger without damaging anything.
Now all he needs to do is give it an Internet connection or maybe make it remote-controlled…
Film is projected at a rate of 24 frames per second, which is sufficient to create the POV illusion. A projector’s shutter inserts itself between the lamp and the lens, blocking the light to prevent projection of the film’s physical movement. But these short periods of darkness, or flicker, present a problem. Originally, shutters were made in the shape of a semi-circle, so they block the light half of the time. Someone figured out that increasing the flicker rate to 60-70 times per second would have the effect of constant brightness. And so the modern shutter has three blades: one blocks projection of the film’s movement, and the other two simply increase flicker.
