November 2007
Intermediate to advanced
736 pages
46h 32m
English
Content preview from Consumer ElectronicsBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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MEGAPHONES
Portable electronic megaphones, Fig. 26.19 are used by construction workers, law-enforcement officials, boat navigators and so on. The unit comprises a reentrant horn speaker with a microphone mounted on the back.
A 5-transistor class-B amplifier is typically employed to step-up the microphone signal. The unit is powered with a 9 volt battery and has a maximum output of 8 watts with a sound range of 600 yards. A volume control is provided and a built in siren signal source is available in the unit shown in Fig. 26.19. Yet another design is shown in Fig. 26.20. This is a 20 watt unit and provides more than twice as much as the portable unit. A switch is provided to change the circuit configuration into a sensitive directional listening ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.