Fire siren

This LM3909 circuit produces a rapidly rising wail upon pressing the button, and a slower `coasting down` sound upon release. If it is desirable to have the tone stop sometime after the button is released, an 18-k © resistor can be placed between pins 8 and 6 of the LM3909. The sound is then much like that of a motor-driven siren, National Semicon

ductor Linear Applications Handbook, 1991 p. 402.

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