CMOS Clock Oscillators C3290-FREQ. In the event we do not have stock. The following series can be substituted for C3290-freq. The frequencies must be the same: CE3290- C3292- CE3292- C3291- CE3291- C3390-FREQ. In the event we do not have stock. The following series can be substituted for C3390-freq. The frequencies must be the same: CE3390- C3392- CE3392- C3391- CE3391- 5-0704-56