%
% instamp
%
r = 3.6;
source([0 0],'V_1','h');
opamp([4 1],4,0);
plot([3 4],[0 0],'k','linewidth',1.5)
resist([10 -1],'h','R_1','y_1')
resist([13.6 -1],'h','R_2','y_2')
plot([8 10],[-1 -1],'k','linewidth',1.5)
plot([10 10],[-1 -2],'k','linewidth',1.5)
resist([10 -2],'v','R_3','y_3')
resist([10 -2-r],'v','R_4','y_4')
resist([10 -2-2*r],'v','R_3','y_5')
plot([10 10],[-2-3*r -3-3*r],'k','linewidth',1.5)
plot([3 10],[-5.6 -5.6],'k','linewidth',1.5)
plot([3 3],[-5.6 -2],'k','linewidth',1.5)
plot([3 4],[-2 -2],'k','linewidth',1.5)
b = -3*(1+r);
opamp([4 b+2],4,1)
plot([3 10],[-5.6-r -5.6-r],'k','linewidth',1.5)
plot([3 3],[-5.6-r b+1],'k','linewidth',1.5)
plot([3 4],[b+1 b+1],'k','linewidth',1.5)
resist([10 b],'h','R_1','y_6')
resist([13.6 b],'h','R_2','y_7')
plot([8 10],[b b],'k','linewidth',1.5)
source([0 b-1],'V_2','h');
plot([3 4],[b-1 b-1],'k','linewidth',1.5)
plot([0 0],[0 b-3],'k','linewidth',1.5)
ground([0 b-3],'')
opamp([15 -5.4],4,1)
plot([13.6 13.6],[-1 -6.4],'k','linewidth',1.5)
plot([13.6 15],[-6.4 -6.4],'k','linewidth',1.5)
plot([13.6 13.6],[-8.4 b],'k','linewidth',1.5)
plot([13.6 15],[-8.4 -8.4],'k','linewidth',1.5)
plot([19 20],[-7.4 -7.4],'k','linewidth',1.5)
plot([20 20],[-7.4 -1],'k','linewidth',1.5)
plot([20 17],[-1 -1],'k','linewidth',1.5)
plot([10+2*r 10+2*r],[b b-3],'k','linewidth',1.5)
ground([10+2*r b-3],'')
text(10,-.3,'x_1')
text(13,-.3,'x_2')
text(10,-14.4,'x_3')
text(13,-14.4,'x_2')
text(10.4,-5.5,'V_1')
text(10.4,-9.5,'V_2')
text(18,-.3,'x_4')
axis off
hold off
return