Universal Ding-Dong

Universal Ding-Dong

The circuit may use the (original) bipolar version of the 555 timer IC, or its more recent CMOS equivalents. If a CMOS equivalent is used, standby current is likely to be below 2mA.

That is, an AA alkaline battery pack would last about two months on standby. For longer periods, a regulated power supply is recommended. The supply voltage will ideally be 12V, but may be reduced to 9V.

Copyright Rev. Thomas Scarborough
[Contact the author of this article at scarboro@iafrica.com]

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