Starting indicator for gas turbines

Claim 1

AN ARRANGEMENT FOR INDICATING WHEN BOTH THE STAGES OF A TWO STAGE GAS TURBINE ENGINE, HAVING A HIGH PRESSURE STAGE AND A LOW PRESSURE STAGE, HAVE STARTED, COMPRISING A TACHOMETER GENERATOR FOR INDICATING ROTATION OF THE SHAFT AT HIGH SPEEDS AND AN INDICATOR CIRCUIT FOR INDICATING ROTATION OF THE SHAFT AT VERY LOW SPEEDS, SAID INDICATOR CIRCUIT COMPRISING A TRANSISTOR AMPLIFIER INCORPORATING D.C. COUPLED STAGES AND A SWITCHING STAGE, A POWER SUPPLY FOR SAID AMPLIFIER, AN ISOLATING TRANSFORMER CONNECTED BETWEEN THE INPUT OF SAID AMPLIFIER AND A WINDING OF SAID TACHOMETER GENERATOR FOR FEEDING A PORTION OF THE A.C. VOLTAGE FROM THE TACHOMETER GENERATOR TO THE AMPLIFIER, A LAMP CONNECTED TO THE OUTPUT OF SAID SWITCHING STAGE, MEANS FOR FEEDING THE AMPLIFIED SIGNAL TO SAID SWITCHING STAGE AND MEANS CONTROLLING THE ENERGISATION OF SAID LAMP BY THE OUTPUT FROM SAID SWITCHING STAGE SO THAT THE LAMP FLASHES IN SYNCHRONISM WITH THE ROTATION OF SAID SHAFT AT LOW SPEED OF ROTATION OF THE SHAFT AND AT HIGHER SPEEDS OF ROTATION OF SAID SHAFT THE LAMP IS LIT SUBSTANTIALLY CONTINUOUSLY.