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Automatic Selenium Diode Recovery Time Meter

IP.com Disclosure Number: IPCOM000097244D
Original Publication Date: 1962-Jul-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Sandfelder, M: AUTHOR [+2]

Abstract

The circuit uniformly measures and records the reverse recovery time of selenium semiconductor diodes. The current time characteristic of a selenium diode is indicated. The reverse recovery time for a specified current level is designated by Tf. Parameter Tf is defined as the time between the points on a current waveform, when the diode is switched from a forward to a reverse bias condition.

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Automatic Selenium Diode Recovery Time Meter

The circuit uniformly measures and records the reverse recovery time of selenium semiconductor diodes. The current time characteristic of a selenium diode is indicated. The reverse recovery time for a specified current level is designated by Tf. Parameter Tf is defined as the time between the points on a current waveform, when the diode is switched from a forward to a reverse bias condition.

In the circuitry for measuring Tf is a power supply 20 and an associated switching device 22 for changing the direction of the output current. Supply 20 is connected through load resistor 24 to one terminal of two terminal device 26 under test. The other terminal of 26 is connected to an offset current source 28 including D. C. voltage source 30 and resistor 32. The other terminal also connects to amplifier 34. This inverts the current output pulse of device 26 and converts it into a voltage pulse. The output of amplifier 34 is limited by a second amplifier 36 and Zener diode 38. The effect of the amplifiers 34 and 36 is to produce a negative square wave of known amplitude. Its width is proportional to the stored current of device 26 supplied as an input to amplifier 36 and the offset current established by source 28.

The output from amplifier 36 is supplied through isolating diode 40 to operational integrator 42. The latter's output voltage is supplied to peak follower 44 which provides a voltage analogous to the diode recovery ti...