Ladies and gentlemen, for your valve entertainment we bring to you an unremarkable audio valve from the 1930s. The Cossor 402P is an audio triode of, by modern standards, a miserable device!
From the start of the AC/DC chassis era, this is part of a whole raft of series heater devices. This one requires 40 volts at 200mA to light it up. Yes folks, that's 8 whole watts to energise the heater.
Then, with your 200 volts of HT, you can supply a further 3 watts to ultimately obtain your 0.75 watts of audio, which Cossor described as 'adequate for domestic purposes'.
That equates to a little less than 7% efficiency.
Sadly, it took a World War to consign this miserable device to history.
From the start of the AC/DC chassis era, this is part of a whole raft of series heater devices. This one requires 40 volts at 200mA to light it up. Yes folks, that's 8 whole watts to energise the heater.
Then, with your 200 volts of HT, you can supply a further 3 watts to ultimately obtain your 0.75 watts of audio, which Cossor described as 'adequate for domestic purposes'.
That equates to a little less than 7% efficiency.
Sadly, it took a World War to consign this miserable device to history.
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