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|caption=Tektronix 175 | |caption=Tektronix 175 | ||
|introduced=1961 | |introduced=1961 | ||
|discontinued=(? | |discontinued=(?) | ||
|designers= | |designers= | ||
|manuals= | |manuals= | ||
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The '''Tektronix 175''', [[introduced in 1961]], is an external unit that extends the current capability of the [[575|575 curve tracer]]. | The '''Tektronix 175''', [[introduced in 1961]], is an external unit that extends the current capability of the [[575|575 curve tracer]]. | ||
The 175 uses the standard circuit topology for the collector supply: a variac followed by a multi-tap | The 175 uses the standard circuit topology for the collector supply: a variac followed by a multi-tap isolation transformer, followed by full-wave rectifiers. | ||
isolation transformer, followed by full-wave rectifiers. | |||
There are two modes: | There are two modes: | ||
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Separate transformer taps and rectifiers are used for the two modes. | Separate transformer taps and rectifiers are used for the two modes. | ||
In the 0-20 V mode, [[45L10]] rectifiers are used. | In the 0-20 V mode, [[45L10]] rectifiers are used. | ||
Unlike the 575, which routes the test current through the front panel switches, the 175 routes the 0-20 V collector supply through 100 A relays, whose coil current are switched by the front panel (i.e., the "COLLECTOR POLARITY" and "TRANSISTOR SELECTOR") controls. | Unlike the 575, which routes the test current through the front panel switches, the 175 routes the 0-20 V collector supply through 100 A relays, | ||
whose coil current are switched by the front panel (i.e., the "COLLECTOR POLARITY" and "TRANSISTOR SELECTOR") controls. | |||
Otherwise, the front panel switches would have to handle high currents and would be massive and difficult to operate. | Otherwise, the front panel switches would have to handle high currents and would be massive and difficult to operate. | ||
The front panel switches are break-before-make, which is important because if the relay coils were to be energized in the wrong combination, a short circuit would be formed. | The front panel switches are break-before-make, which is important because if the relay coils were to be energized in the wrong combination, a short circuit would be formed. | ||