Bell transformer supply for wave-file player

If the wave-file player described in the February 1999 issue of this magazine is used as a programmable doorbell, it is, of course, handy if its supply is derived from the doorbell transformer. In the design of the circuit in the diagram, it was borne in mind that as little as possible should be changed in the existing wiring of the doorbell and that it would be convenient to be able to switch the doorbell back on when the wave-file player is removed to program it with a new sound.