NBS 560-Series Random Sampling Timebase

In 1972, Jim Andrews was employed by the United States National Bureau of Standards (NBS) and built this random sampling timebase for 560-series mainframes. The motivation for this plug-in was that NBS needed to measure pulse signals with fast rise time but very low repetition rate. Tektronix offered the 3T2 random sampling timebase, but it wasn't intended for very low repetition rates. A prototype of the instrument was built and a report was written. The report includes schematics.

• NBSIR 73-309 Random Sampling Oscilloscope Time Base, Jim Andrews, June 1973

The timebase was intended for use in a Tektronix 564 mainframe. The bistable storage of the 564 is essential for the low rep rate measurement, i.e., the ability to accumulate the trace point by point over a period of time that is longer than the persistence of a non-storage scope.

• 
• 

  The power supply is at the left. The board at the top is the strobe predictor. The board at the bottom is the horizontal amplifier.

• Jim Andrews, Random Sampling Oscilloscope for the Observation of Mercury Switch Closure Transition Times. IEEE Transactions on Instrumentation and Measurement, Vol. IM-22 No.4, December 1973, p.375+