When you take a shower, wouldn't it be nice to have music playing in the background the whole time? The same is true of this simple circuit. As long as your shower is on, it will play different songs over and over again. As soon as the water comes out of the shower, the music starts. When you turn the shower "off" and the water stops coming out of it, the music stops.

Fig. 2: Sensor arrangement In Figure 1, you can see how the musical water shower works. It has a pair of complementary amplifiers made up of transistors T1 and T2, a switch made up of transistor T3, and a 12-tone melody generator called IC M3482. The M3482 is a mask- ROM-programmed IC that plays melodies based on the data that was put into it. The built-in preamplifier makes it easy to connect to the driver circuit, which is made up of transistors T4 and T5. The IC can be changed out with another one from the UM348xx series, the WR630173, or the WE4822. When the shower is turned on, power is sent to the melody section by way of the T3 transistor. As shown in Fig. 2, the overhead shower unit has two insulated copper cables labeled AD and BC. The insulation is taken off of a part of the cable AD (marked A'D'). The cable AD is fixed firmly and runs along the body of the shower so that the bare part doesn't touch the body and cause a short. The part that isn't covered should be long enough so that the shower water falls on it as it runs. At C, the body of the shower is soldered to the end of the copper cable BC. It is tightened by wrapping it around the neck. So, the cable ends at A and B can be plugged into the circuit of Fig. 1 as sensor inputs. Now, when you turn on the shower, water falls on the bare copper wire A'D', which makes an electrical connection with the cable BC that runs through the shower and is also in contact with running water. The cable points A and B on the

shower unit are connected to the circuit of Fig. 1 as sensor inputs. This lets the power reach the base of the transistor T1, which is now conducting. This makes the T2 and T3 transistors work. So, the power source is there for the melody circuit (Fig. 1). The melody generator IC is set up to play twelve different tunes over and over again until the shower water is running and transistors T1, T2, and T3 are conducting. The preset VR1 can be used to change how loud the melody generator tunes are. When the shower is turned off, both transistors T1 and T2 turn off. At the base of pnp transistor T3, a high voltage builds up. So, transistor T3 stops making electricity. This causes the power to be cut off to the melody generator circuit, which stops making music. When the shower is turned off, the circuit doesn't use much power, so the battery lasts a long time. Put the circuit together on a general-purpose printed circuit board (PCB) and put it in a plastic case with LED1 and switch S1 on the outside. Connect the A and B ends of the sensor wires to the wires on the shower.