Rangkaian Detektor Signal AF/RF
The following circuit of special functions to detect the presence or absence of signal AF / RF. This circuit is very simple so as to make it requires a relatively low cost. Detektor Signal AF/RF circuit based an audio amplifier and a loudspeaker with a switch input to the AF and RF signal. The whole device can be made as small as possible so that it can be included in a container to keep the peace.
Audio amplifier section in this series created by IC TDA 2822M, with a low-power stereo amplifier in 8-pin mini-DIP. This IC is used as a bridge cofiguration to minimize output power up to 250 mW, the loudspeaker is in use 4 ohm, 500mW. Current required is less than 10mA with a 3V battery voltage.