Scientech Technologies Pvt. Ltd. Supplies Single Phase Controlled Rectifier with RAMP Comparator Firing Scheme, ST2708. Scientech Technologies Pvt. Ltd. Is an ISO 9001:2000 certified company and is the manufacturer and supplier of test and measurement instruments. The Single Phase Controlled Rectifier is a compact and ready to use power electronics experiment board with a ramp comparator firing circuit on the board. The Single Phase Controlled Rectifier facilitates different types of experimentations by connecting the patch cords. It comes with a user manual, built in power supply and gradual firing angle control upto 180 degree.