Alan, In earlier testing (before I discovered the wonderful world of marine hailers) an attempt was made to use only the pcb board from similar 50 watt hand held bullhorns as the amplification for an underwater communications console. These were used in a similar manner as the lower transmit or "b" channel of DIY communications consoles in that this was "on" or active to transmit one's voice. When talking, it generated tons of heat that normally would have been dissipated. By hot I mean really hot! When used as originally intended, only when one pushed the talk button did power get applied to this card and it was allowed it to cool between transmissions. It was not designed to operate so confined in a small enclosure. I could have pursued this farther but hailers were found to do this job better and at a reduced cost. David Bartsch From: alanjames@xtra.co.nz To: personal_submersibles@psubs.org Subject: Re: [PSUBS-MAILIST] donation Date: Sat, 10 Jul 2010 13:10:10 +1200 Hi David,
Was it one particular component overheating in the bull horns?
Could it not have had a heat sink on it that maybe extended into the water?
I've been looking into the heating issue a little bit, with referance to my
pulse width modulators. They have a couple of Mosfetts that get quite hot.
I saw one PWM (on a truck) wich was only 12 volt 30 amps & had heat sinks
that extended out of its casing & a fan to cool the heat sink. However I
Googled & couldn't find any referance to them being a fire hazard.
Alan
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