Musical Touch Bell UM66

This musical call bell circuit can be operated by just bridging the gap between the touchplates with one’s fingertips. Thus there is no need for a mechanical ‘on’/‘off’ switch because the touch-plates act as a switch. Other features include low cost and low power consumption. The bell can work on 1.5V or 3V, using one or two pencil cells, and can be used in homes and offices. Two transistors are used for sensing the finger touch and switching on a melody IC. Transistor BC148 is npn type while transistor BC558 is pnp type. The emitter of transistor BC148 is shorted to the ground, while that of transistor BC558 is connected to the positive terminal.

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Musical Touch Bell UM66

Music Generator, IC UM66

UM66 is a pleasing music generator IC which works on a supply voltage of 3V. the required 3V supply is given through a zener regulator. its out put is taken from the pin no1 and is given to a push pull amplifier to drive the low impedance loud speaker. A class A amplifier before push pull amplifier can be used to decrees the noise and improve out put. UM66 is a 3 pin IC package just looks like a BC 547 transistor.

Circuit diagram:

A Continuous Music Generator Circuit Diagram