GB628406A - Improvements in and relating to amplitude monitors - Google Patents

Abstract

628,406. Monitoring amplitude of electric oscillations. GENERAL ELECTRIC CO., Ltd., and BRYDEN, J. E. Feb. 25, 1947, No. 5480. [Class 40 (v)] In an amplitude monitor, voltage pulses are produced in response to parts of oscillations exceeding a certain amplitude and relays are adapted to actuate indicating devices in response to the voltage pulses. The signal to be monitored is applied to a jack 16, Fig. 2, amplified by means of valves 17 and 18 and developed across the primary winding 23 of a transformer 22. In the circuit of the secondary winding 21 are two diodes 24, 25, biassed to be normally non-conductive so that if the peak level of the oscillation appearing across the half of the secondary winding exceeds this bias a negative pulse is produced across a load resistor 33. This pulse is applied by means of contacts A1 of a normally operated relay A, to an electronic relay consisting of valves 37, 38 and 39 as described in Specification 628,409. When the anode current of valve 37 falls below a critical value, due to the effect of the applied pulse, the relay A in the anode circuit is released and the contacts A1 assume the position shown, disconnecting valve 37 from further impulses. When the contacts of relay A are released as shown in Fig. 3, a condenser 53 is charged through a resistance 54 from a current source from terminals 55, 56. The electronic relay is designed to return to its normal condition after three seconds so that the relay A then assumes its operated condition and a second relay B is then energized by means of condenser 53. If no further pulses arrive on the suppressor grid of valve 37 the relay B becomes de-energized after one second. If, however, a second pulse arrives during this second the relay B remains operated, being energized via contacts B1 and A3 until the relay A once more assumes an operated condition. The relays are supported so that when relay A is first released an indicating device is operated, and if the relay A is released a second time during the period of energization of the relay B a second indicating device is operated in addition (Fig. 4, not shown).