J
I´m a electrical engineering student and I urgently need some help. I need a cheap circuit (schematic with components values)that warms a little furnace using a power wirewound resistor in 60Hz line. The heat level (90 -250 graus celcius) is controlling by a output of a PLC (S7300), using voltage output 0-5V or/and 4m-20mA and a feedback inptut of the same PLC from a temperature sensor. The SCR´s firing must be made using PWM modulation (frequency carrier=1KHz).