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OK, just for fun, here's a problem for all you electronics buffs.
This is a real life situation.
A 100 volt line loudspeaker network broadcasts three different signals:
a) Fire Alarm Tone, a continuous 400Hz square wave.
b) Class change 'pips' a pulsed (on-off) 1Khz square wave.
c) Speech from a microphone.
The office staff don't want to hear the microphone annoucements or the class change pips, but obviously for health and safety reasons they must hear the fire alarm signal. The office staff work in two rooms, each with it's own 100 volt line loudspeaker.
The question is 'How would you block the unwanted signals being broadcast from those loudspeakers yet allow the fire alarm signal to be heard?'
There are 88 other loudspeakers on the school site powered by 2 x 100 watt amplifiers and the three different audio signals are prioritised through a logic circuit, with the Fire Alarm having greatest priority.
Circuit diagram please
I actually solved this problem 18 years ago and had it patented, now it's your turn
This is a real life situation.
A 100 volt line loudspeaker network broadcasts three different signals:
a) Fire Alarm Tone, a continuous 400Hz square wave.
b) Class change 'pips' a pulsed (on-off) 1Khz square wave.
c) Speech from a microphone.
The office staff don't want to hear the microphone annoucements or the class change pips, but obviously for health and safety reasons they must hear the fire alarm signal. The office staff work in two rooms, each with it's own 100 volt line loudspeaker.
The question is 'How would you block the unwanted signals being broadcast from those loudspeakers yet allow the fire alarm signal to be heard?'
There are 88 other loudspeakers on the school site powered by 2 x 100 watt amplifiers and the three different audio signals are prioritised through a logic circuit, with the Fire Alarm having greatest priority.
Circuit diagram please

I actually solved this problem 18 years ago and had it patented, now it's your turn
