Generate Dual Voltages That Track By Percentage Of Range


Posted on Feb 7, 2014

Consider the need to vary two voltages, V1 and V2, by an equal percentage of their ranges (V1MAX - V1MIN) and (V2MAX - V2MIN), with V1MAX, V1MIN, V2MAX, and V2MIN independent of each other. The first idea that comes to mind is to use ganged potentiometers (Fig. 1). However, ganged potentiometers are notorious for producing tracking errors as high


Generate Dual Voltages That Track By Percentage Of Range
Click here to download the full size of the above Circuit.

as 5%. Here`s a simple method that uses a single potentiometer to generate two or more tracking voltages with an accuracy of better than 0. 5% of range (Fig. 2). The circuit around IC1a is a square-wave oscillator. Triangular waves across C1 are applied to comparator IC1b. Potentiometer P1 varies the duty cycle of the pulses at the comparator output from 0% to 100%. Transistor Q1 and the multiplexer switch IC2 convert the comparator output into pulses with well defined edges. These pulses are applied to the digital control inputs of the analog multiplexer that receives V1MAX, V1MIN, V2MAX, and V2MIN as the analog inputs. The multiplexer outputs, which are integrated by components R7-C2 and R8-C3, are buffered by IC1c and IC1d. The oscillator`s frequency is optimized to be about 5 kHz. This frequency is high enough to produce negligible ripple in the integrator output. At the same time, the frequency is low enough to ensure that rise and fall times of the pulses are negligible compared to the pulse repetition period. Note that capacitors C2 and C3 must be low-leakage types. This idea can be extended to generate more tracking voltages by using additional multiplexer switches, integrators, and buffers.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Low-power-rs-232c-driver
    Controlling a Mazda Car Using an iPhone
    Electrical_Subsystem
    LAN RJ45 Cable Connection Tester
    40 m band direct conversion
    one time only burglar alarm
    variable step up dc dc converter 2
    IR Short Distance Beam Cut Detector
    MIDI Drum Machine Schematic Main CPU Section
    Vacuum State Electronics FVP5A tube preamp
    LMD18400 for four-phase stepper motor drive



    Top