Why use unreliable electronics? just go to the diy store and buy an old fashioned electromechanical chime, transformer and microswitch. use the "backdoor" coil. it chimes when the switch closes and is quiet when the switch opens. or be fancy, use the "frontdoor" coil, high chime when the switch closes and a low chime when it opens. (a door open and a door closed chime, wow ;-) and only $12 total parts.
ultimate no energy system, hang a bell from the door ;-) but brass cow bells are expensive these days. (cat collar, $1 from the dollar store?) and it's unique these days. have fun, larry 6/1/05 9:13:17 PM, [EMAIL PROTECTED] wrote: >David: > >Here's a thought.......you could use a alarm system mag/reed contact unit to >pull a ground and fire a one shot timer type ckt. using an NE555 timer. >I've got an ol' RS enjuneer's handbook 'round here....saw in one of the >tumultuous piles that exist in my office.......You know the one that Forrest >Mims >wrote for them in the good ol' days, when they sold electronics parts instead >of >cell phones. > > >So.. the thought being...you could rig this lil circuit to fire on the N.O. >to N.C.and pull the ground to fire the one shot, then when the door closes >the reed would go back to N.O. and the ckt. would reset for the next >pull.....found it.....yeah a one shot tone burst set at 880Hz...and you could >build a >little Power supply...or ...hey run it off a ..bbb.....battery! _________________________________________________________________ KX-T Mailing list --- http://kxthelp.com/ Subscription changes: http://kxthelp.com/mailman/listinfo/kxt
