Browse Prior Art Database

ELECTRONIC ROTARY ANALOG SWITCH WITH BINARY OUTPUTS

IP.com Disclosure Number: IPCOM000005429D
Original Publication Date: 1980-Aug-01
Included in the Prior Art Database: 2001-Oct-10
Document File: 3 page(s) / 119K

Publishing Venue

Motorola

Related People

Jaime A. Borras: AUTHOR

Abstract

This paper describes a multi-position switch using electronic circuits to convert the analog voltages from a potentiometer to a binary output. The advantages of this structure are: small size, low cost, a minimum number of interconnects, no switch bounce circuitry, expandability and an output that is readi- ly available in a binary format.

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MOTOROLA Technical Disclosure Bulletin Vol. 1 No. 1 August 1980

ELECTRONIC ROTARY ANALOG SWITCH WITH BINARY OUTPUTS By Jaime A. Borras

ABSTRACT

  This paper describes a multi-position switch using electronic circuits to convert the analog voltages from a potentiometer to a binary output. The advantages of this structure are: small size, low cost, a minimum number of interconnects, no switch bounce circuitry, expandability and an output that is readi- ly available in a binary format.

INTRODUCTION

  The electronic rotary analog switch was invented to replace the very large and expensive mechanical rotarv switches which reauire one interconnect for each of their switch positions. The electronic rotary analog switch serves as a'space saver at a lower cost and it minimizes the number of interconnects from the control panel to the system's PC board or hybrid. The potentiometer is mounted on the control panel and its wiper is routed to the system's PC board. Th analog voltages from the wiper are then compared to preset voltages on the system's PC board circuitry to provide the proper binary output, thus eliminating the need for a decimal to binary converter.

  The original conception of this invention is shown in Figure 1 which illustrates a structure for a four position switch. The electronic circuit consists of a potentiometer, seven resistors and one (open collec- tor) quad voltage comparator (MC 3302). Outputs A and B decode in binary the four voltage levels cor- responding to each switch position. The switch positions are outlined by markers on the control panel around the potentiometer's control knob or with a detent mechanism. (Refer to Figure 2 for details of the markings and the voltage ranges.)

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CIRCUIT DESCRIPTION

  There are four voltage ranges for the four positions switch configuration (refer to Figures 1 and 2). A reference voltage was chosen at the beginning of these ranges to preset the triggering levels of the voltage comparators. The labels for each position are chosen at the center of the voltage range to provide maximum noise immunity.

   The wiper, while in position 1, provides approximately 56 V to the voltage comparators. Since this voltage is lower than the preset voltages VW, Vp3 and Vp4, comparators Cl and C2 are positively satura...