112: Difference between revisions
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[[File:Tek 112 front.jpg|thumb|200px |right]] | |||
The '''Tektronix 112''' is a DC-coupled differential amplifier [[introduced in 1950]]. | The '''Tektronix 112''' is a DC-coupled differential amplifier [[introduced in 1950]]. | ||
The voltage gain can be set from 0.5 to 5000 V/V. | The voltage gain can be set from 0.5 to 5000 V/V. | ||
The frequency response is DC to 2 MHz when the gain is set | The frequency response is DC to 2 MHz when the gain is set below 166, and DC to 1 MHz for gain settings greater than that. | ||
below 166, and DC to 1 MHz for gain settings greater than that | |||
The first stage is a differential amplifier using a pair of | The 121 is intended for use with the [[511]], [[512]], [[514]], and [[524]] oscilloscopes. | ||
[[5879]] pentodes. Next is a differential amplifier using | The input impedance is 1 MΩ in parallel with 47 pF. The output impedance is 8000 Ω. | ||
a pair of [[12AU6]] pentodes. | The amplifier's schematic and response are identical to that of a [[512|Tek 512]]. | ||
The first stage is a differential amplifier using a pair of [[5879]] pentodes. | |||
Next is a differential amplifier using a pair of [[12AU6]] pentodes. | |||
The 112 has an unusual output coupling stage. | The 112 has an unusual output coupling stage. | ||
It provides output short circuit protection and | It provides output short circuit protection and shifts the common-mode DC level of the differential output to 0 V. | ||
shifts the common-mode DC level of the differential output to 0 V. | The plate voltage of the final gain stage (just before the output coupling stage) is about +150 V. | ||
The plate voltage of the final gain stage | |||
(just before the output coupling stage) is about +150 V. | When enabled, the output coupling stage is a a pair of constant current sinks. | ||
When enabled, | |||
the output coupling stage is a a pair of constant current sinks. | |||
It uses [[6CB6]] pentodes for this. | It uses [[6CB6]] pentodes for this. | ||
This shunt current causes a constant voltage drop | This shunt current causes a constant voltage drop across output resistors, resulting in 0 V at the output. | ||
across output resistors, | The cathodes of the output coupling stage are supplied by the -150 V rail, allowing them | ||
resulting in 0 V at the output. | to operate as proper current sources when their plates are at 0V. | ||
The cathodes of the output coupling stage are | |||
supplied by the -150 V rail, | |||
allowing them to operate as proper current sources | |||
when their plates are at 0V. | |||
* [http://w140.com/tek_112.pdf Tektronix 112 Manual (PDF)] | * [http://w140.com/tek_112.pdf Tektronix 112 Manual (PDF)] | ||
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<gallery> | <gallery> | ||
Tek 112.jpg|1955 Catalog photo | |||
Tek 112 front.jpg|Manual photo | |||
Tek 112 main schematic.png|Main schematic | |||
Tek_112.power_supply.png|Power Supply Schematic | |||
Tek 112 calibrator schematic.png|Calibrator Schematic | |||
</gallery> | </gallery> | ||
[[Category: | [[Category:Differential amplifiers]] | ||
[[Category:Introduced in 1950]] | [[Category:Introduced in 1950]] | ||
Revision as of 23:22, 20 July 2017
The Tektronix 112 is a DC-coupled differential amplifier introduced in 1950. The voltage gain can be set from 0.5 to 5000 V/V. The frequency response is DC to 2 MHz when the gain is set below 166, and DC to 1 MHz for gain settings greater than that.
The 121 is intended for use with the 511, 512, 514, and 524 oscilloscopes. The input impedance is 1 MΩ in parallel with 47 pF. The output impedance is 8000 Ω. The amplifier's schematic and response are identical to that of a Tek 512.
The first stage is a differential amplifier using a pair of 5879 pentodes. Next is a differential amplifier using a pair of 12AU6 pentodes.
The 112 has an unusual output coupling stage. It provides output short circuit protection and shifts the common-mode DC level of the differential output to 0 V. The plate voltage of the final gain stage (just before the output coupling stage) is about +150 V.
When enabled, the output coupling stage is a a pair of constant current sinks. It uses 6CB6 pentodes for this. This shunt current causes a constant voltage drop across output resistors, resulting in 0 V at the output. The cathodes of the output coupling stage are supplied by the -150 V rail, allowing them to operate as proper current sources when their plates are at 0V.
Internal photos needed.
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1955 Catalog photo
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Manual photo
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Main schematic
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Power Supply Schematic
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Calibrator Schematic
