3A74: Difference between revisions
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The Tektronix Type 3A74 is a four-channel vertical plug-in [[introduced in 1963]] for | The Tektronix Type 3A74 is a four-channel vertical plug-in [[introduced in 1963]] for | ||
560-series scopes. The bandpass is DC to 2 MHz. Each input signal passes through | [[560-series scopes]]. The bandpass is DC to 2 MHz. Each input signal passes through | ||
switchable input attenuators and then into a cathode-follower made from a 7586 | switchable input attenuators and then into a cathode-follower made from a [[7586]] | ||
Nuvistor triode. That drives a PNP differential amplifier. The output of this | Nuvistor triode. That drives a PNP differential amplifier. The output of this | ||
differential amplifier, for each of the four channels, passes through a diode-based | differential amplifier, for each of the four channels, passes through a diode-based |
Revision as of 16:09, 29 April 2011
The Tektronix Type 3A74 is a four-channel vertical plug-in introduced in 1963 for 560-series scopes. The bandpass is DC to 2 MHz. Each input signal passes through switchable input attenuators and then into a cathode-follower made from a 7586 Nuvistor triode. That drives a PNP differential amplifier. The output of this differential amplifier, for each of the four channels, passes through a diode-based analog signal switching network (multiplexer). The output of that multiplexer drives the output amplifier, which is part transistor, part tube. The one-hot select line signals for the multiplexer are generated by a transistor-based ring oscillator, a four-state cyclic state machine. This allows each of the input signals to be traced on the screen, one after another.