Relaxation oscillator

About: Relaxation oscillator is a research topic. Over the lifetime, 1952 publications have been published within this topic receiving 22326 citations.

Start-up control for DC motors

Abstract: Start-up power control of a full wave rectifier supply to a DC permanent magnet motor is provided by an SCR full wave rectifier bridge and a start-up control circuit for the SCR's comprising an independent rectifier for charging up a capacitor through a high impedance path to produce a start-up ramp voltage, a UJT relaxation oscillator powered by the independent rectifier bridge to trigger the SCR's through a transformer, and a series transistor control circuit for the UJT responsive to the ramp voltage to advance the firing angle of th UJT and thereby advance the firing angle of the SCR's as the ramp voltage increases fron 0 to a maximum.

Apparatus and method for a thermal feedback oscillator

Abstract: A method and apparatus is directed to generating an oscillation frequency utilizing the thermal heat transfer properties of semiconductor material as a feedback loop in an oscillator. The oscillator includes a comparator that compares two input signals and enables one of two heater circuits. Each heater circuit is thermally coupled to a sensor and reference circuit. Each sensor and reference circuit pair is arranged such that the reference circuit is heated while the sensor cools. The combination of each sensor and reference circuit produces input signals for the comparator. The frequency of the oscillator is determined by the heat transfer rate between the heater circuit and the corresponding sensor, and the thermal cooling rate of the other sensor. Changing the biasing currents, and distances between the heat sources and the thermal sensors adjust the duty cycle and frequency.

Coupled relaxation oscillators with highly stable and accurate quadrature outputs

Abstract: Coupled relaxation oscillators can have extremely accurate and stable quadrature outputs. A model is presented to predict the stability of the phase relation. It is confirmed by measurements and shows the power of the concept.

A new CMOS astable multivibrator and its nonlinear analysis

Abstract: We present a nonlinear analysis of a new inductively tuned astable multivibrator obtained by connecting a timing inductor across a composite nonlinear resistor with a characteristic of N-type, which is made up of the parallel connection of two complementary pairs of cross-coupled MOS devices Some possible practical applications of the circuit are also envisaged Closed-form expressions for the amplitude and the period of the periodic oscillation are derived in both cases when the circuit exhibits a relaxation oscillation and in the more difficult case when, due to the effect of parasitic capacitances of the devices, the circuit has an almost-discontinuous relaxation oscillation with a nonzero switching time The accuracy of the presented formulas, which are useful for both the analysis and design, is validated through circuit simulations and experimental results Copyright © 2009 John Wiley & Sons, Ltd

Application of the double relaxation oscillation superconducting quantum interference device sensor to micro-tesla 1H nuclear magnetic resonance experiments

Abstract: We developed an ultra-low field (ULF)-nuclear magnetic resonance (NMR) measurement system capable of working with a measurement field (Bm) of several micro-tesla and performed basic NMR studies with a double relaxation oscillation superconducting quantum interference device (DROS) instead of conventional dc-SQUIDs. DROS is a SQUID sensor utilizing a relaxation oscillation between a dc-SQUID and a relaxation circuit; the new unit consists of an inductor and a resistor, and is connected in parallel with the SQUID. DROS has a 10 times larger flux-to-voltage transfer coefficient (∼mV/ϕ0) than that of the dc-SQUID, and this large transfer coefficient enables the acquisition of the SQUID signal with a simple flux-locked-loop (FLL) circuit using room temperature pre-amplifiers. The DROS second-order gradiometer showed average field noise of 9.2 μϕ0/√Hz in a magnetically shielded room (MSR). In addition, a current limiter formed of a Josephson junction array was put in a flux-transformer of DROS to prevent excess...