I am able to read the ac voltage by clipping the lower cycle and using resistor divider to scale the 300Vac to Round 5 v positive half cycle peak......
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Now i am able to read the peak of this cycle after sensing the interrupt on zero crossing :i.e the moment i detect a high at transistor bc547 collector...i start taking samples and read the peak of readings in upper half cycle....Now i am instantly able to read the voltage ......
By using other method of converting the ac to dc using a cap to filter the wave ,decreased the response time.....which could not be used in stabilizer....coz i have to switch the relay in the very next cycle of detecting the fluctuating ac voltage .....
now the sensing part is fine . but i m facing problem in switching the relay 25A 24V dc Relay.I am trying to switch it as follows :
1. there is a tapping from the autotransformer which is around 18v ac , which i am using for two purposes :
a. Driving my mcu card which senses voltage and displays it on seven segment ,does the processing for switching relays .
b. Using the same supply and converting it to 24V dc using a diode bridge and 1000uf cap 35V .for driving the uln2003 for relays....
The moment the relays switches on and off i face problem as:
a. There is spike on my mcu card 5V power supply....
b. in some cases when a relay switched for switching higher winding tapping of the autotransformer , The mcu card stops working the display gets stuck ,,all the relays show 0V across them and there is humming in the auto transformer .
PLease suggest what to do for this........