The circuit for making PWM

I told already that we are searching for a circuit to make a PWM signal with the analog output of the Labjack ( varies from 0 to 5 V ).

We found something that first makes a triangle waveform , and then makes with this triangle waveform makes a PWM signal.

Triangle waveform:

http://pcbheaven.com/circuitpages/Triangle_Wave_Generator/










PWM Generator:
http://pcbheaven.com/circuitpages/Voltage_Controlled_PWM_Generator/

But when we build it on a breadbord it seems that this is not quite stable.
So we ask our teacher of Electronics and he let us see a schematic in the handbook of Malvino. But we build it and tested it today while we have Electronics Lab. But this is only the part of making a triangle waveform.
But the circuit for making the PWM signal doesn't work yet. We need to do more tests.