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112: Difference between revisions
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and short wires can connect the 112 to the oscilloscope's CRT. | and short wires can connect the 112 to the oscilloscope's CRT. | ||
A two-position switch on the rear panel of the Type 112 controls the common-mode output voltage. | A two-position switch on the rear panel of the Type 112 controls the common-mode output voltage. | ||
In one position, the common-mode output voltage is | In one position, the common-mode output voltage is +150 V, | ||
In the other position, the common-mode output voltage is | which is the plate voltage of the [[6AG7]] tubes of the output amplifier. | ||
In the other position, the common-mode output voltage is 0 V. | |||
The shifting of the common-mode output voltage 150 V downward is accomplished | The shifting of the common-mode output voltage 150 V downward is accomplished | ||
by enabling a pair of 680 μA DC current sinks that cause a voltage drop on 220 kΩ series output resistors. | by enabling a pair of 680 μA DC current sinks that cause a voltage drop on 220 kΩ series output resistors. | ||
[[6CB6]] pentodes form the current sinks, with their cathodes tied to -150 V. | [[6CB6]] pentodes form the current sinks, with their cathodes tied to -150 V. | ||
The 220 kΩ output resistors also provide short circuit protection. | The 220 kΩ output resistors also provide short circuit protection. | ||
The Type 112 manual recommends 0 V for driving the CRT of the [[511]], | |||
and +150 V for driving the CRT of the [[512]], [[513]], or [[514]]. | |||
* [http://w140.com/tek_112.pdf Tektronix 112 Manual (PDF)] | * [http://w140.com/tek_112.pdf Tektronix 112 Manual (PDF)] | ||