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This circuit shows how far integration can be taken: IC1, a Type HT82207 from Holtek does virtually everything. Only a (small) loudspeaker and the necessary selectors need to be added. The standard 18-pin Type HT82207 is an integrated sound generator, producing sounds typical of the Old West. The various sounds are selected by S1–S6 as listed below. In the quiescent state, the circuit draws a current not exceeding 1 µA. S1 – bugle S2 – neighing S3 – sound of hooves S4 – pistol shot S5 – crack of a rifle S6 – cannon fire

Normally cell batteries have a shelf life of 2 to 5 years under normal use . After that time we have to replace them . Nowadays there replacement batteries which are cheap, but these batteries last for much less cost only months. An easy solution is to use batteries in a circuit that requires less current , we can use them for lighting LEDs .  How to Reuse Old Cell Battery for LED lighting