The Wisconsin Oscillator: A Low-Cost Circuit for Powering Ion Guides, Funnels, and Traps

In this work, we present the Wisconsin Oscillator, a small, inexpensive, low-power circuit for powering ion-guiding devices such as multipole ion guides, ion funnels, active ion-mobility devices, and non-mass-selective ion traps. The circuit can be constructed for under $30 and produces two antiphase RF waveforms of up to 250 V_p-p in the high kilohertz to low megahertz range while drawing less than 1 W of power. The output amplitude is determined by a 0-6.5 VDC drive voltage, and voltage amplification is achieved using a resonant LC circuit, negating the need for a large RF transformer. The Wisconsin Oscillator automatically oscillates with maximum amplitude at the resonant frequency defined by the onboard capacitors, inductors, and the capacitive load of the ion-guiding device. We show that our circuit can replace larger and more expensive RF power supplies without degradation of the ion signal and expect this circuit to be of use in miniature and portable mass spectrometers as well as in home-built systems utilizing ion-guiding devices.