My dad approached me with an interesting problem to solve ... the doorbell in their house is hard to hear from the tv room or dining room. Given that 90% of the deliveries made to the house are stuff I've ordered, I had vested interest to solve this. The usual solution to this is to buy one of the wireless doorbells that has 1 switch and multiple bell units -- you just stick the switch to your gate, and place the bell units wherever you like. However there were some good reasons against t...