Calling Bell

This is a very simple circuit consisting of only two components,  a three pin ic UM66 or BT66 and a transistor BC548. this is a very easy method to make a calling bell. the circuit can be made without soldering also. i used a cassette box as outer covering     parts list 1 x UM66 1 x BC548 1 ...
By: sooraj619

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Source: http://www.instructables.com/id/Calling-Bell/

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