Telephone Ringer with 556 dual timers

Telephone Ringer with 556 dual timers Circuit diagramUsing articulate ellipsoidal after-effects of altered time periods, The ambit presented actuality produces campanology tones agnate to those produced by a telephone.The ambit requires four astable multivibrators for its working. Therefore two 556 ICs are acclimated here. The IC 556 contains two timers (similar to 555 ICs) in a distinct package