TunnelDiodeElm.java

/*    
    Copyright (C) Paul Falstad and Iain Sharp
    
    This file is part of CircuitJS1.

    CircuitJS1 is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 2 of the License, or
    (at your option) any later version.

    CircuitJS1 is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with CircuitJS1.  If not, see <http://www.gnu.org/licenses/>.
*/

package com.lushprojects.circuitjs1.client;

//import java.awt.*;
//import java.util.StringTokenizer;

class TunnelDiodeElm extends CircuitElm {
    public TunnelDiodeElm(int xx, int yy) {
	super(xx, yy);
	setup();
    }
    public TunnelDiodeElm(int xa, int ya, int xb, int yb, int f,
			  StringTokenizer st) {
	super(xa, ya, xb, yb, f);
	setup();
    }
    boolean nonLinear() { return true; }
    void setup() {
    }
    int getDumpType() { return 175; }
	
    final int hs = 8;
    Polygon poly;
    Point cathode[];
	
    void setPoints() {
	super.setPoints();
	calcLeads(16);
	cathode = newPointArray(4);
	Point pa[] = newPointArray(2);
	interpPoint2(lead1, lead2, pa[0], pa[1], 0, hs);
	interpPoint2(lead1, lead2, cathode[0], cathode[1], 1, hs);
	interpPoint2(lead1, lead2, cathode[2], cathode[3], .8, hs);
	poly = createPolygon(pa[0], pa[1], lead2);
    }
	
    void draw(Graphics g) {
	setBbox(point1, point2, hs);

	double v1 = volts[0];
	double v2 = volts[1];

	draw2Leads(g);

	// draw arrow thingy
	setPowerColor(g, true);
	setVoltageColor(g, v1);
	g.fillPolygon(poly);

	// draw thing arrow is pointing to
	setVoltageColor(g, v2);
	drawThickLine(g, cathode[0], cathode[1]);
	drawThickLine(g, cathode[2], cathode[0]);
	drawThickLine(g, cathode[3], cathode[1]);

	doDots(g);
	drawPosts(g);
    }
	
    void reset() {
	lastvoltdiff = volts[0] = volts[1] = curcount = 0;
    }
	
    double lastvoltdiff;
    double limitStep(double vnew, double vold) {
	// Prevent voltage changes of more than 1V when iterating.  Wow, I thought it would be
	// much harder than this to prevent convergence problems.
	if (vnew > vold+1)
	    return vold+1;
	if (vnew < vold-1)
	    return vold-1;
	return vnew;
    }
    void stamp() {
	sim.stampNonLinear(nodes[0]);
	sim.stampNonLinear(nodes[1]);
    }
    static final double pvp = .1;
    static final double pip = 4.7e-3;
    static final double pvv = .37;
    static final double pvt = .026;
    static final double pvpp = .525;
    static final double piv = 370e-6;
    void doStep() {
	double voltdiff = volts[0] - volts[1];
	if (Math.abs(voltdiff-lastvoltdiff) > .01)
	    sim.converged = false;
	//System.out.println(voltdiff + " " + lastvoltdiff + " " + Math.abs(voltdiff-lastvoltdiff));
	voltdiff = limitStep(voltdiff, lastvoltdiff);
	lastvoltdiff = voltdiff;
	
	double i = pip*Math.exp(-pvpp/pvt)*(Math.exp(voltdiff/pvt)-1) +
	    pip*(voltdiff/pvp)*Math.exp(1-voltdiff/pvp) +
	    piv*Math.exp(voltdiff-pvv);
	
	double geq = pip*Math.exp(-pvpp/pvt)*Math.exp(voltdiff/pvt)/pvt +
	    pip*Math.exp(1-voltdiff/pvp)/pvp
	    - Math.exp(1-voltdiff/pvp)*pip*voltdiff/(pvp*pvp) +
	    Math.exp(voltdiff-pvv)*piv;
	double nc = i - geq*voltdiff;
	sim.stampConductance(nodes[0], nodes[1], geq);
	sim.stampCurrentSource(nodes[0], nodes[1], nc);
    }
    void calculateCurrent() {
	double voltdiff = volts[0] - volts[1];
	current = pip*Math.exp(-pvpp/pvt)*(Math.exp(voltdiff/pvt)-1) +
	    pip*(voltdiff/pvp)*Math.exp(1-voltdiff/pvp) +
	    piv*Math.exp(voltdiff-pvv);
    }
    void getInfo(String arr[]) {
	arr[0] = "tunnel diode";
	arr[1] = "I = " + getCurrentText(getCurrent());
	arr[2] = "Vd = " + getVoltageText(getVoltageDiff());
	arr[3] = "P = " + getUnitText(getPower(), "W");
    }
}