doorbell - or telephone - operated flash-light - deal for the hard of hearing

doorbell — or telephone - operated flash-light elektor november 1983 It was, of course, known before the outbreak of disco fever that flash-lights can be used in fields other than photography. The following design uses a common-or-garden battery-operated electronic flash to indicate when the doorbell or the telephone rings. doorbell - or telephone - operated flash-light ... ideal for the hard of hearing la Figure la. In this part of the circuit diagram can be seen the power supply, the doorbell converter, and the relay for operating the flash-light. B1 = B40C2200 B2 = B40C1000 P 83104-1a R5 Figure lb. The circuit diagram of the telephone converter: @ and 0 are connected to the corresponding terminals in figure la. In this version, B2 and C3 in figure la are not used. 83104-lb The hard of hearing are often unable to hear the doorbell or telephone ringing, but many of us who aren"t can find ourselves in that situation. For instance, when your new, powerful vacuum cleaner is being ...