GB1044651A - Improvements in or relating to audience reaction measuring systems - Google Patents

Abstract

1,044,651. Transistor circuits. SCREEN GEMS Inc. March 11, 1963 [March 20, 1962], No.9619/63. Heading H3T. [Also in Division G4] A system for measuring the response of an audience to a performance includes a transistorized pulse generator and a transistorized digital resolver which energizes one of a number of output lines corresponding to the level of a D.C. analog input. The resolver consists of a chain of threshold devices each comprising a bi-stable transistor pair Q 3 , Q 4 which conducts when triggered to remove a blocking signal fed through a resistor 135 to the base of a transistor Q5, switching on a fixed potential output on the corresponding line 162 provided that no other blocking signal is applied on an inhibit lead 164 or from the next threshold device of the chain. Each transistor Q 3 requires a different input level to trigger it, this value increasing with each successive stage. Thus, for example, if the third stage is the last to be triggered, all of the first three threshold devices comprising transistors Q 3 , Q 4 of these stages will be conducting, but transistor Q5 of the third stage only will conduct as the second and third stages send blocking signals back to the bases of transistors Q5 of the first and second stages via resistors 142. The generator (Fig. 8, not shown) includes a capacitor 170 which gradually charges from a positive source through a variable resistor 172 until a unijunction transistor 167 is triggered to conduction, discharging the capacitor through a resistor 169. This discharge surge is differentiated by a capacitor 173. The start produces a positive pulse which is passed to the base of an NPN transistor 175 causing it to conduct and thus earth an output 209 normally maintained at a positive potential via a resistor 177; thus an output comprising a steady potential with evenly spaced zero pulses is produced. The end of the discharge surge causes a transistor 181 to conduct momentarily. The output of this latter transistor is differentiated by a capacitor 189 and the positive pulse is passed by a polarity selector 190 to trigger an NPN transistor pair 192, 197 to the conducting state. The pair are linked as a bi-stable pair but a capacitor 210 renders the circuit monostable so that it returns to the non-conducting state after a predetermined time. While the monostable circuit conducts, the positive potential developed at collector 199 of transistor 197 is passed by a capacitor 200 to cut off an output transistor 202, thus reducing the normally positive output. Since these drops in the output potential are only used in a check cycle the output is maintained at the positive potential during normal operation by a bi-stable pair Q 6 , Q,. Normally transistor Q 7 is non-conducting and transistor Q 6 conducts and the output potential is maintained through a resistor 219. When a check cycle is required a negative pulse is received on a line 225 causing a change of state so that transistor Q 7 conducts, reducing the output of the bi-stable circuit to zero, and thus reverse-biasing a diode 237 so that the drops in output of the pulse generator circuit may take effect. At the end of a clock cycle a negative pulse, i.e. zero in place of a normally positive signal, is received from a line 230 to switch the bi-stable circuit from its normal prohibit state.