Posted on Oct 20, 2012 11133
This circuit uses only one IC, produces a pleasant tone, and sports a single control for adjusting the tone`s chiming rat
e. IC1A and IC1B form an astable multivibrator, which produces the circuit"s basic tone. The multivibrator"s frequency is: The component values produce a 668-Hz tone. IC1C buffers the multivibrator"s output to the 8- speaker. Current-limiting resistor R2, determines the speaker"s volume. R2 minimum value is 220 . IC1D and IC1E form an asymmetric, astable multivibrator, which adds a chime effect to the circuit"s basic tone. The chime effect"s frequency is: R7 gives this rate multivibrator a slowly varying output signal to produce a pleasant decay for the chime effect. IC1F is an inverting amplifier for the chime multivibrator.