Remote FM Bell (Switch)

To annoy neighbors by ringing their door bell again and again is something everybody enjoys doing. But how often do we think of making this annoying instrument on our own? And well, how about making it into a melodious device..!!

Multyremotes here is high again with its new set of projects based on Radio frequency (RF). Remote FM Bell is a very interesting project. Quite analogous to the one commercially available, this wireless FM bell gives a sweet melody output. It can also be used as a remote to operate AC/DC from remote areas within range of the FM transmitter. Well, its justified if you ask me –“Why go for a complex FM remote controller when even a simplex IR remote does the same job for us?” But the designer has got resolved grey areas in resonance to this implementation:

· The range of operation is increased upto 5 times.

· The device can be operated from anywhere within the radius of 50 metres.

For making a remote bell, you need a FM transmitter, a FM receiver and an operating circuit. This circuit is a little complex and hence can be divided into three phases:

1. Simple FM bell

2. Switch for remote bell and finally,

3. Remote bell with melody output.

The Simple FM bell is an audio frequency oscillator which generates an audio frequency signal whenever the switch is pressed. This audio signal is transmitted by the FM transmitter and received by the Fm receiver which is tuned to the transmitter’s frequency.

The Simple FM bell circuit is then modified for remote fm bell switch by replacing the multivibrator with a phased lock loop. The receiver circuit consists of IC 567(PLL), IC 555 (monostable multivibrator) and UM 66 which is a melody generator IC. Here, the transmitter actually works as a remote or wireless switch for the bell.