  Frequency generators are widely used in electronics. Here, we report the
design and experimental realization of a memristive frequency generator
employing a unique combination of only digital logic gates, a single-supply
voltage and a realistic threshold-type memristive device. In our circuit, the
oscillator frequency and duty cycle are defined by the switching
characteristics of the memristive device and external resistors. We demonstrate
the circuit operation both experimentally, using a memristor emulator, and
theoretically, using a model memristive device with threshold. Importantly,
nanoscale realizations of memristive devices offer small-size alternatives to
conventional quartz-based oscillators. In addition, the suggested approach can
be used for mimicking some cyclic (Sisyphus) processes in nature, such as
"dripping ants" or drops from leaky faucets.
