Browse Prior Art Database

Light Sensitive Oscillator

IP.com Disclosure Number: IPCOM000095155D
Original Publication Date: 1965-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Huang, SS: AUTHOR

Abstract

This circuit responds to a light at the junction of transistor T3 to produce a signal at output 4. Transistors T2 and T3 are interconnected by a phase-shifting network of resistors and reactances to form a phase-shift oscillator. The components have values so that the circuit oscillates at a low amplitude when T3 is not illuminated. It oscillates at a high amplitude when T3 is illuminated.

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Light Sensitive Oscillator

This circuit responds to a light at the junction of transistor T3 to produce a signal at output 4. Transistors T2 and T3 are interconnected by a phase-shifting network of resistors and reactances to form a phase-shift oscillator. The components have values so that the circuit oscillates at a low amplitude when T3 is not illuminated. It oscillates at a high amplitude when T3 is illuminated.

The oscillations of the transistors form a carrier. The amplitude of the light produces a modulation of this carrier that appears at the collector of T2. This circuit is useful in distinguishing between differences in light that occur when light is reflected from two different materials.

Transistors T6, T7 and T8 form an amplifier coupling the signal at the collector T2 to output 4. This amplifier is preferably overdriven to produce a binary output. When the circuit is used to distinguish between two materials, the circuit is highly sensitive to small differences in light and is useful in various kinds of apparatus operating on a subject according to differences in the light it reflects.

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