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Non-Saturating Feedback Switching Circuit

IP.com Disclosure Number: IPCOM000098850D
Original Publication Date: 1958-Jun-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Strohm, WG: AUTHOR [+2]

Abstract

This device discloses a non-saturating feedback type transistor switching circuit, and features means for preventing the saturation of the complementary transistors of the switching circuit. This means comprises an emitter follower transistor on the input transistor, and a voltage divider responsive to the emitter follower transistor for switching.

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Non-Saturating Feedback Switching Circuit

This device discloses a non-saturating feedback type transistor switching circuit, and features means for preventing the saturation of the complementary transistors of the switching circuit. This means comprises an emitter follower transistor on the input transistor, and a voltage divider responsive to the emitter follower transistor for switching.

When the -5.7 volt input level is placed on the input of transistor No. 1, it conducts and pulls 6 ma through the 75 ohm resistor at the output. This establishes a -.3 volt level output. During this time, transistor No. 2 is cut off by clamping the emitter of No. 2 more negative than -6V which keeps No. 2 reverse biased. This is due to the drop in potential in the emitter of No. 1. With No. 2 off, the voltage divider places a +6.3 volts on the base of No. 4, which keeps the base of No. 4 reverse bias. Transistor No. 5 is on and clamps the emitter of No. 4 at +6.3 volts.

When the -6.3 volt level is placed at the input of Transistor No. 1, it will be cut off due to the reverse bias which is placed on the emitter of No. 1 and No. 2 conducts. With No. 2 on, the voltage divider will place a + 5.7 volts on the emitter of No. 4 which causes it to conduct and send 6 ma through the 75 ohm resistor in the opposite direction. This establishes the +.3 output level. During this time, No. 5 is off due to the reverse bias on its emitter. Transistor No. 3 is on at all times and serves the purp...