You may use this wireless light switch instead of physical contact with switches which may be dangerous if there is any shorting. The wireless light switch circuit described here requires no physical contact for operating the appliance.
You just need to move your hand between the infrared LED (IR LED1) and the phototransistor (T1). The IR rays transmitted by IR LED1 is detected by the phototransistor to activate the hidden lock, flush system, hand dryer etc.
This wireless light switch is very stable and sensitive compared to other AC appliance control circuits. It is simple, compact and cheap. Current consumption is low in milliamperes. The circuit is built around an IC CA3140, IRLED1, phototransistor and other discrete components.
The working of the circuit is simple. In order to switch on the appliance, you simply interrupt the infrared rays falling on the phototransistor through your hand. During the interruption, the appliance remains on through the relay. When you remove your hand from the infrared beam, the appliance turns off through the relay.