DESIGN AC POWER CONTROL USING TRIAC AND DIAC

CIRCUIT DESIGN SUPPOSE THAT TOTAL RESISTANCE IS 56K AT A POT POSITON THE TIME CONSTANT RC = 56K * .3uF  = 16.8 ms figure -1 -charging diagram of capacitor From  figure -1 time constant is the time required to reach 63.2% total voltage HOW TO FIND FIRING ANGLE Our input A.C. voltage is 230AC RMS Then the peak voltage = √2 × Vrms = 325V then the the voltage at  time constant = 63% of  peak voltage =63% * 325 =204 for diac used is DB3 which has break down voltage of 30V from its datasheet Vs=Vin(1-e^-T/RC) Vs=Vin(1-e^-T/16.8ms) 30=325(1-e^-T/16.8ms) 30=325(1-e^-T/16.8ms) ^{0.0923076923076923 =}(1-e^-T/16.8ms) e^{-T/16.8ms =1-0.0923076923076923} e^{-T/16.8ms  = 0.9076923076923077} e^T/16.8ms  =1/0.9076923076923077 e^T/16.8ms  =1.10 solving T/16.8ms  =.1 T=.1 * 16.8ms   T=1.68ms   firing angle=( 1.68/10) *180 firing angle =30