# UJT for SCR AC to DC rectificer help

#### whywhy68

Joined Jun 11, 2008
13
i am doing a SCR AC to DC rectificer of 220V 50hz sine input

so if i wan to use a UJT relaxation osciliator to fire the SCR, do i need to fixed the frequency of the osciliator to 50 hz as well ? if yes, then f = 1.44/RC , what abt the firing angle ? is it control by varying the Rb1 or Rb2 resistance value while keeping the osciliator frequency at 50hz

#### beenthere

Joined Apr 20, 2004
15,819
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