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7B85: Difference between revisions
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The [[7B85]]/[[7B80]] combination was introduced in 1976 to replace the 200 MHz [[7B71]]/[[7B70]] that had no digital delay read-out. For the [[7104]] 1 GHz-class scopes, the [[7B15]]/[[7B10]] provide the functionality of 7B85/7B80. | The [[7B85]]/[[7B80]] combination was introduced in 1976 to replace the 200 MHz [[7B71]]/[[7B70]] that had no digital delay read-out. For the [[7104]] 1 GHz-class scopes, the [[7B15]]/[[7B10]] provide the functionality of 7B85/7B80. | ||
From Tekscope Vol.8 No.1, 1976: | |||
<blockquote> | |||
[[Les Larson]] developed the trigger circuitry and served as Project Manager for the 7B80 and 7B85. | |||
The sweeps were designed by [[Bruce Hofer]] and the DVM and related logic by [[Paul Farley]]. Much credit is due [[Art Metz]] for his work on the trigger input 1C which includes the peak-to-peak automatic trigger circuitry. | |||
[[Gene Andrews]], Program Manager, provided overall direction for the project. | |||
</blockquote> | |||
{{BeginSpecs}} | {{BeginSpecs}} | ||
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==Internals== | ==Internals== | ||
The 7B85 uses a [[155-0185-00]] digital voltmeter IC (U686). | The 7B85 uses a [[155-0185-00]] digital voltmeter IC (U686). A ramp generator is started when the trigger signal arrives. | ||
A ramp generator is started when the trigger signal arrives. | The delayed sweep is started when a comparator detects that the ramp has reached a control voltage, set by the front panel knobs on the 7B85. | ||
The delayed sweep is started when a comparator detects that the ramp has reached a | |||
control voltage, set by the front panel knobs on the 7B85. | |||
The control voltage is proportional to the amount of delay. | The control voltage is proportional to the amount of delay. | ||
The digital voltmeter in the 7B85 digitizes the control voltage and displays it | The digital voltmeter in the 7B85 digitizes the control voltage and displays it on the [[7000 series readout system|oscilloscope readout]], | ||
on the [[7000 series readout system|oscilloscope readout]], thereby providing the | thereby providing the operator with a precise readout of the delay. | ||
operator with a precise readout of the delay. | |||
Another way of setting up a precisely delayed timebase is to use a [[7D11]] digital delay module | Another way of setting up a precisely delayed timebase is to use a [[7D11]] digital delay module. | ||
The 7B85 uses the +50 V supply provided by the mainframe. | The 7B85 uses the +50 V supply provided by the mainframe. | ||
==Links== | ==Links== | ||
* [[Media:Tekscope_1976_V8_N1.pdf|Delta time measurement for the 7000 series. Tekscope Vol.8 No.1, 1976 | * [[Paul Farley]], [[Les Larson]], and [[Bruce Hofer]]: ''[[Media:Tekscope_1976_V8_N1.pdf|Delta time measurement for the 7000 series]]''. In Tekscope Vol.8 No.1, 1976, p.2 | ||
* [https://m.youtube.com/watch?v=Hz-gF_XSj9w Demonstration of delay and delta time measurement on a 7B85] | * [https://m.youtube.com/watch?v=Hz-gF_XSj9w Demonstration of delay and delta time measurement on a 7B85] | ||