Telequipment S51B and S51E free download

File name S51B_and_S51E.pdf

T E L E Q U I P M E N T OSCILLOSCOPE TYPE S51B A N D S51E All TelequipmenT instruments are the subject of continuous development and improvement, and, in consequence, may incorporate minor detail changes from the information contained herein. TelequipmenT is a registered trade mark of TELEQUIPMENT LIMITED* 313 Chase Road Southgate London, N. 14. England. Telephone: 01-882 1166 Cables: TELEQUIPT LONDON N 14 CIRCUIT DESCRIPTION VERTICAL AMPLIFIER The vertical amplifier consists of three double triodes. Vla and b form a cathode coupled amplifier stage with RV6 acting as the gain control. The signal is taken from Vlb anode and drives the output stage V3 via cathode follower V2a. V3 consists of a long-tailed pair with the signal taken to V3a and the vertical shift applied to V3b. V2b acts as a low impedance HT supply for V1, also providing approximately 15OV for Y shift and timebase circuits. The signal at the anode of V3b is taken to the INT-EXT trigger switch. The HT supply for the trigger circuit, V4 and V5b is taken from a common resistor R15 in the cathode circuit of V3. TRIGGER CIRCUIT The trigger selection is performed by three switches in the S51B and one in the S51E; S2 selects the INT-EXT triggering signal and connects it to the grid of phase splitter V4b. S3 selects the positive or negative output of the phase splitter and connects it to S4 which either passes the signal directly or via an integrating circuit to V4a. The latter position, TV FIELD, integrates the field pulses of a television waveform and attenuates the line pulses allowing the time base to be triggered by the field sync pulses. From S4 the signal is fed to V4a and V5b which form a cathode coupled bistable switch, the switching level being adjusted by the grid potential of V4a. On the AUTO position the switch S5 is opened and the grid of V4a is returned to the grid of V5b. In the absence of a signal V4a and V5b oscillate at a frequency determined by the time constant R42 and C19, but as soon as any input signal between about 50Hz and 1MHz is applied to the grid of V4a, the self-oscillation ceases and the multivibrator synchronises to the signal frequency. The square wave appearing at the anode of V5b is differentiated, the positive pulse removed by MR7 and the negative pulse used to trigger the time base. TIMEBASE & H O R I Z O N T A L AMPLIFIER V6a is the Mi l ler sweep generator, the speed of run down being controlled by S8 and the VARIABLE speed control. The Miller valve is keyed by V5a and V6b which together form a d .c. c o u p l e d multivibrator. In the rest position of the timebase, V5a is off and its anode potential is clamped by MR8 and 9. V6b is conducting. A negative trigger