Any old VCR has a programmable timer that connects to motors for recording TV shows. This is analogous to feeding a cat, and following this principle, you can convert a VCR into a weekend pet feeder. You set the VCR’s timer, and when feeding time comes, the motor that would ordinarily spin the video head operates a food delivery mechanism instead. You can even program different size portions for different days, for times when you plan on returning midday. Like some vending machines, the feeder uses an auger mechanism, a helical shaft, to propel food from a hopper into the pet’s bowl. You can use the same basic mechanism to drop food into a fish tank.