GB1096121A - Recording system for macbain balances and the like - Google Patents

Abstract

1,096,121. Measuring weight electrically. COMMISSARIAT A L'ENERGIE ATOMIQUE. Jan.8, 1965 [Jan. 10, 1964], No.922/65. Heading G1N. Extension of a spring in, for example, a balance, is measured by attaching a magnetically permeable mass 2, Fig. 2, to its lower end, and measuring the current required in a solenoid 6 in order to hold the mass in a given position. The solenoid is connected in one arm of a bridge circuit, an inductance 10 being connected in a second arm to balance the solenoid inductance, and the solenoid current is varied by varying the voltage applied to the bridge from an autotransformer 15. The top of the autotransformer is moved by a motor 16 when the relay contacts 20 are closed; and with the bridge initially balanced by means of a potentiometer 11 with the mass 2 outside the solenoid, the motor increases the bridge voltage until the mass 2 is drawn far enough into the solenoid 6 to unbalance the bridge. The bridge unbalance voltage is detected at 18, and this opens the relay contacts 20 to de-energize the motor and prevent further increase in the bridge voltage. A recorder 17 monitors the bridge voltage required to hold the mass 2 in the given position. The mass 2 may be a ferrite slug covered with a sheath of glass, and the spring-mass assembly is contained in a glass envelope. The balance may be used for weighing a substance undergoing chemical or thermal reaction as a means of analyzing the substance. A plurality of balances may be monitored at will by means of a rotary switch connecting them in turn to the bridge circuit.