opamp_piezo_buffer.ngjs

#!/usr/bin/env ngspicejs
// Testing DC coupled gain using opamp
// linter: ngspicejs-lint
"use strict";

battery('U1', 3, 0, 9);
opamp('Q1', 1, 2, 3, 0, 2, 'TL071');
var r1 = resistor('R1', 3, 1, '20k');
var r2 = resistor('R2', 1, 0, '20k');
capacitor('C1', 6, 1, '10u');
capacitor('C2', 2, 7, '10u');
resistor('R3', 7, 0, '50k');
pickup_piezo('U2', 6, 0);

var t = tran().run().chart('V(2)');
echo('Gain ' + t.gain(1, 2).toEng());

// very poor base response with 20k virtual ground divider
var a = ac().fstop('2k').run();
echo('AC base response using 20k:20k virtual ground:');
a.chart('V(7)');

// change VG resistors to 1M
r1.r('1M');
r2.r('1M');
a = ac().fstop('2k').run();
echo('AC base response using 1M:1M virtual ground:');
a.chart('V(7)');

battery_sensitivity('U1', 6, 7, 3, 15).run().chart({min_x: 0}).last_chart.gif('bat_sens_opamp_piezo_buffer.gif');