Interpolating Scanner Circuit

Posted on Feb 6, 2014

This is an original design for an interpolating scanner, a circuit with a number of signal inputs, a control voltage input and a signal output. The output effectively selects between the inputs, fading from one to the next, as the control voltage rises. A two-channel panner circuit might be considered a degenerate form of a scanner. The data sheet

Interpolating Scanner Circuit
Click here to download the full size of the above Circuit.

for the Precision Monolithics, Inc. SSM-2024 current-controlled amp IC shows a stereo panner, they call it an "Exponential Cross-Fade Controller", where two CCAs are controlled from a PNP differentialamp. The circuit is pretty straightforward and I`m sure similiar circuits have been used before. The circuit presented here is inspired by and similiar to JH`s scanner except that drive circuit is an unusual extrapolation of the differential amplifier topology used in the PMI panner. This approach has some advantages: the total drive current (the sum of all the drive currents) is from a constant current source assuring that the sum of the individual gains is held constant Figure 1 below shows a block diagram of the Interpolating Scanner. There is a Current Controlled Amplifer (CCA) of traditional design for each signal input. Each CCA interfaces appropriately to the input signal, has a current source output, and a gain (transconductance) that is directly proportional to its control current input. The CCA outputs are summed by shorting them directly together. A buffer amplifier stage provides the appropriate output level and impedance. The CCAs are transconductance amplifiers; the input is a voltage, the output is a current, the gain is linearly proportional to the control current, and in this case the control current is expected to be from 0. 0 to 2. 0 mA. More on this later. In the schematic above, the opamp provides a...

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    IR auto digital thermostat
    Light Switch with 555 Timer
    LPG Gas Leakage Sensor Alarm
    lm723 variable power supply circuit design
    Camera1 Module
    l297 stepper motor controller circuits
    2 transistor fm transmitter
    A 12V Car Charger For ASUS Eee Notebook
    Electric Fence 20KV pulses for perimeter defense
    High-Linearity Analog Optocouplers
    Sawtooth Signal Generator
    Double interlocking three-phase asynchronous motor control circuit
    Pulse signal generating circuit and display
    Hardware circuit C51 microcontroller serial communication