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Ah i see, i thought you just wanted to block the pips. I'll have to have another think on this one...
Quiz/Question
- Thread starter floppybootstomp
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Me__2001
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speakers are work on electrical pulses so assuming the different speakers can be set to work using different pulses you can set the microphone through the amp to send the specific signal to work the different speaker for the type of broadcast
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OK, me spill de beanz.
Where everybody seems to have erred is thinking only of frequency blocking to get around the problem. Bear in mind that one of the signals we wish to block is a speech pattern from a microphone, which covers a large frequency range.
As mentioned previously all audio signals arrive at each loudspeaker modulated with 100 volts. A transformer within the loudspeaker enclosure removes the 100 volts and presents the remaining and original audio to the loudspeaker cone.
I mentioned time as a clue. Three signals are present: Pips, which are pulsed (on-off); Speech, which is irregular and consists of highs, lows and pauses; Fire alarm signal, which is continuous. So only one of those three signals is continuous.
We can use that feature to enable switching. Here's how it's done.
First, we position a double pole relay's switch contacts between the 100 volt line transformer secondary and the loudspeaker cone. We now need a DC voltage to initiate the relay, thus joining the loudspeaker core to the transformer output.
We take the incoming 100 volts and semi smooth it to give a rough DC. The DC level is used to charge a capacitor. When the capacitor fills up and becomes fully charged, it will switch the relay.
A resistor is used to limit the incoming 100 volts, to suit localised line voltages as a 100Volt line signal will vary between 60 and 100 volts, depending on the size of the loudspeaker network and the power of the amplifier used.
As the pips and the microphone signals are irregular, they're never 'on' long enough for the capacitor to become fully charged. The fire alarm signal, however, is continuous and after about 5 to 10 seconds, will 'top up' the capacitor, initialise the relay and switch the loudspeaker on, allowing the fire alarm signal to sound.
And that's how it's done. Here's a rough sketch, I don't actually have the circuit diagram with me at the moment, excuse the roughness of it.
And yes, if somebody was to hum in the midrophone loudly for ten seconds, that would trip the relay as well, but they never do
Where everybody seems to have erred is thinking only of frequency blocking to get around the problem. Bear in mind that one of the signals we wish to block is a speech pattern from a microphone, which covers a large frequency range.
As mentioned previously all audio signals arrive at each loudspeaker modulated with 100 volts. A transformer within the loudspeaker enclosure removes the 100 volts and presents the remaining and original audio to the loudspeaker cone.
I mentioned time as a clue. Three signals are present: Pips, which are pulsed (on-off); Speech, which is irregular and consists of highs, lows and pauses; Fire alarm signal, which is continuous. So only one of those three signals is continuous.
We can use that feature to enable switching. Here's how it's done.
First, we position a double pole relay's switch contacts between the 100 volt line transformer secondary and the loudspeaker cone. We now need a DC voltage to initiate the relay, thus joining the loudspeaker core to the transformer output.
We take the incoming 100 volts and semi smooth it to give a rough DC. The DC level is used to charge a capacitor. When the capacitor fills up and becomes fully charged, it will switch the relay.
A resistor is used to limit the incoming 100 volts, to suit localised line voltages as a 100Volt line signal will vary between 60 and 100 volts, depending on the size of the loudspeaker network and the power of the amplifier used.
As the pips and the microphone signals are irregular, they're never 'on' long enough for the capacitor to become fully charged. The fire alarm signal, however, is continuous and after about 5 to 10 seconds, will 'top up' the capacitor, initialise the relay and switch the loudspeaker on, allowing the fire alarm signal to sound.
And that's how it's done. Here's a rough sketch, I don't actually have the circuit diagram with me at the moment, excuse the roughness of it.
And yes, if somebody was to hum in the midrophone loudly for ten seconds, that would trip the relay as well, but they never do
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Woah thats awesome!
and you patented this idea so its illegal for someone else to do it unless they pay you obsene amounts of money?
and you patented this idea so its illegal for someone else to do it unless they pay you obsene amounts of money?
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In theory, yes, I suppose so. I was actually surprised the Patent Office accepted the idea, as it's so simple. But apparently it's how the device is used, rather than it's design, that makes the Patent.christopherpostill said:
Mind you, if some enterprising soul in, say, Basingstoke, was to make, sell and fit one after reading this, it's doubtful I'd know of it's existence
But if I saw one for sale in a catalogue, well, that's different.
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i guess you could take a company to court if you found they were doing it...
Its a shame I was away for the weekend and missed out on the quiz (mind you, I had a think about it and I still didn't have a clue