Q: What is GSM?
A: GSM stands for Global System for Mobile communications. It is a communication standard using time division multiple access technique.
Q: What is the frequency range of GSM operates in this project?
A: Frequency range of GSM is 900MHz.
Q: How can I feed the mobile number?
A: One can feed the mobile number by giving a missed call to the SIM number of the GSM modem.
Q: Which energy meter is used?
A: 230VAC, 5-20A Digital energy meter is used
Q: How energy tariff is calculated?
A: An appropriate program in the microcontroller uses the pulses from the energy meter, to calculate the energy unit consumed and hence the per unit cost.
Q: Can it be possible to switch on the lamps?
A: Yes it is possible by sending an SMS.
Q: Is it possible to switch on the lamps?
A: Yes, any electrical load up to 200W can be used.
Q: Which microcontroller is used in this project?
A: A 40 pin microcontroller from 8051 family is used in this project.
Q: How exactly is the pulse reading taken from energy meter?
A: From any digital energy meter internal circuit that delivers one pulse per a certain fraction of one unit is taken from its blinking LED points.
Q: What is the formula for calculating smoothing capacitor value?
A: There is some approximated formula .Peak to peak ripple voltage = Load current in amps / (2*line frequency in hertz *capacitance in farads). But as rule of thumb for 1 A current 1000uF is best. Thus it is load dependent.
Q: What to do when the lamp fails and what is the maximum lamp rating that can be used?
A: If the lamp fails one can use any lamp or bulb which is used in homes up to 100W. We suggest you to go for low watt bulbs.