On 6/17/2012 10:22 AM, Jim W7RY wrote:
> -Has anyone tried an approach like Carel, PC5M, with a microprocessor
> -controlled soft start for the filament. The microprocessor controls an
> -optical triac driver The triac is turned on and off over an increasing
> -portion of the line AC cycle until full on is reached. His
> -microprocessor program does this in 100 sec. It is designed only for
> -soft start and does not do any regulation of the filament voltage after
> -full output is reached.
You don't need a microprocessor to control the triac. Just an RC network
plus a diac.
They are noisy as all get out while ramping up and you only need about 4
seconds for amateur HV supplies and even the Kalifornia KW QRO filaments.
>
> -David
> -KW4DH
>
> Oh PLEASE!
>
> Just put a resistor in line switched with a relay! This is not rocket
> science!
No contacts to clean, simple, and cheap! Emtron amps use the Triac to
ramp up the voltage for the whole amp and it works very well.
73
Roger (K8RI)
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