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Browse Prior Art Database

STEPPED POTENTIOMETER CHANNEL SWITCH

IP.com Disclosure Number: IPCOM000006942D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2002-Feb-11
Document File: 2 page(s) / 95K

Publishing Venue

Motorola

Related People

Adrian Bruce Nickerson: AUTHOR [+2]

Abstract

The conventional method of channel selection is via a multiway switch connected to a microprocessor which strobes the connections to establish the switch position selected. The number of connections required (N) is related to the number of switch positions (M) by the following relationship: M=2(N, or alternatively for N: N = log (M) / log (2) As an example for a typical 16 channel radio 4 con- nections are necessary.

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MO-LA INC. Technical Developments Volume 19 June 1993

STEPPED POTENTIOMETER CHANNEL SWITCH

by Adrian Bruce Nickerson and Tony Rea

ble amount of development effort was necessary to reduce the effect of these limes which were upsetting the phase noise performance of the VCO's necessitating the addi- tion of 8 capacitors and a new board layout).

DESCRIPTION OF INVENTlON

  The invention overcomes the problems above by replacing the mechanical switch with a potentiometer with a stepped action and by replacing the N wires connecting to the microprocessor port with a single wire going into a microprocessor A/D port. The simplest configuration would be to connect the hvo ends of poten- tiometer track to ground and the microprocessor sup- ply and to connect the wiper to the A to D input although other configurations are possible. In any configuration the microprocessor simply monitors the input, works out the wiper position and therefore the channel posi- tion selected. A sketch of the switch is shown in Figure 1 and consists of a potentiometer with an extended shaft
(1) connected to a spring loaded bail bearing (2) via the position selector plate (3). The ball bearing bears on the serated plate (4) resulting in a "stepped" action.

2. Adding or reducing the number of switch positions The combination of stepped potentiometer and sin- involves a complete redesign of the switch and prob- gle connection to a microprocessor A/D port overcomes ably the circuit board to which it is connected. the problems noted in the previous sections as follows:

3. The number of connections between the channel switch 1. The bulk of the stepped switch (l), (2) and (3) would and the microprocessor uses significant board real be the same regardless of application thus ensuring estate as the connected components are frequently very high volumes t...