ODE solve give very spiky response ?

Try to convert one 2-d ODE into two 1-st Odes!

Would suggest that you attach your worksheet.

Would adding more steps in odesolve (third, optional argument) be of help?

Maybe worth a try although i guess that the problem stems from the numeric derivations and not from the result of odesolve.

Hard to be of more hep without having the sheet to play with.

I guess Amax=20 and tf=0.011. What are your values for and   ?

If they are 3 and 5 respectively I get:

Success!

Luc

odesolve use to be mathcad's best solver. however, their statespace solver is much better. the help and quicksheets can get you started. if you want some example files, I can post them. the users here on the forum helped me get a pwm input working. i haven't tried a sawtooth wave but i expect it would handle it well. the nice thing about the statespace solver is it can handle a lot more inputs than odesolve can.