This circuit was described in "Radio" magazine of November, 1977, by L. Mazyra. The circuit uses NAND gates of IC SN5400, it can produce a very low frequency with the stability of a crystal oscillator.
Figure 1. Crystal oscillator circuit with TTL IC.
D1 - 7400 (SN5400); Z1 - a quartz of 1 kHz;
L1 - 3.5 mH; C1 - 820 pF; R1 - 2.7 k
This crystal oscillator circuit (see the Figure 1) can work with a quartz crystal or even without it. If use a capacitor of 240 pF to 1 μF instead of the crystal oscillator, the circuit will produce a frequency in range of 600 Hz to 2 kHz. If decrease the value of the coil L1, the steady work can be performed at the lower frequency.