Power Control Circuit
Using Two SCRs
Maxino, Lorraine Mae M.
Paraiso, Joannacel A.
Potentiometer R controls the angle of conduction of the two
SCRs. The greater the resistance of the pot, lesser will be the
voltage across capacitors C
and hence smaller will be
the time duration of conduction of SCR
During positive half cycle capacitor C
through diode D
, pot R, and diode D
. When the capacitor gets
fully charged, (charge on the capacitor depending upon the
value of R) it discharges through Zener diode Z. This gives a
pulse to the primary and thereby secondary of the transformer
. Thus SCR
, which is forward biased, is turned on
conducts through load R
. During negative half cycle similar
action takes place due to charging of capacitor C
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