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Re: Positive temperature coefficient of Tungsten.

Sorry to intervene ... heater currents are in Ampere range, not 0.6mA. You lost three zeroes somewhere.

Surge current: it's simpler! Current through a cold indirect filament is about 3-4 times higher than a fully warmed up.

Around the nominal Uf voltage, If changes +1% for every +3% of Uf voltage. It's not linear regulation, but approximation is OK in a narrow 'legal' Uf range.

Some actual warmup data - see the link. In the good old days, in addition to brief datasheets, factories issued detailed docs with similar warmup charts, glass surface temperature charts, etc...


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  • Re: Positive temperature coefficient of Tungsten. - klaus 17:06:08 11/21/02 (5)


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