Triangular wave generator
The following circuit which you can simulate in LTSpice will generate a nice triangle waveform of ~200KHz which has a swing from about 0.5V to 4.5V.



Note that it is desirable to use an actual high speed comparator for the Schmidt trigger so that the triangle wave has well defined tips on its waveform. Using an opamp can cause the triangle waveform to get rounded off.