A 25 kHz multivibrator (U2b) clocks flying capacitor switches that first, double 5 V to +10 V (paralleled U1a,c and U2a,c), and then inverts it to -10 V (U1b and U2b)
Figure 1. A 25 kHz multivibrator (U2b) clocks flying capacitor switches that first, double 5 V to +10 V (paralleled U1a,c and U2a,c), and then inverts it to -10 V (U1b and U2b)