|I can't find a picture of the kit or the door, so here's|
the Science Museum
Before I reveal what this project was, I ought to point out something I have since shown to my children at the Science Museum in London. I don't know if it's still there, but last time I went round this particular part of the mueseum I spotted an antique exhibit of an automatic opening door. The first time I went to the Science Museum, aged 6, this door with an 'electric eye' was absolutely mind boggling. You walked up to it, and it opened. Automatically. Like magic. I must have gone through it about a dozen times. This was the future. Really.
So given this context, here's my favourite project with that home kit. As well as the basic electronic circuitry you added a buzzer (and possibly a light) and a pair of wires. At the end of the wires was a little panel with a series of conducting bars. This panel broke the circuit - the buzzer didn't go off. But if the panel got wet, the water conducted electricity across the bars and the buzzer sounded, controlled by a transitor on the board.
So what you could do, for example, is tape the sensor to the side of the bath and leave it filling, careless not bothering to watch it. Surely it would overflow, causing terror and destruction? No! The amazing technology started to buzz and you could turn off the taps. Ah, joy, pure joy. This was twenty-first century living in the 1960s.
Picture from Wikipedia