In this circuit, which uses one of the four comparators of an LM339 (or LM139 or 239), capacitor C1 and resistor R1 must have a time constant that is equivalent to a few times the cycle of the signal produced in order to guarantee an active cycle 50%. The circuit can generate signals up to a few megahertz, depending on the crystal.
| Clique na imagem para ampliar |
