Relaxation oscillator

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

Amplitude-frequency converter circuit

Abstract: 1,088,711. Detecting leaks in a vacuum system electrically. GENERAL ELECTRIC CO. April 30, 1965 [June 5, 1964], No.18375/65. Heading G1N. [Also in Division H4] In a method of detecting leaks in a vacuum system during evacuation thereof, a flow of tracer gas is directed on a localized area of the external surface 53 (Fig.4) of the system 50, and a proportion of the gas is ionized continuously and collected at an electrode 57. At a leak, tracer gas (e. g. nitrogen) is admitted and increases the ionization probability, and thus increases the magnitude of a current in an external circuit connected to the electrode 57. The current is converted in a sensor unit (circuit Fig.1 not shown) into an A. C. signal having an audio frequency that varies in accordance with the magnitude variations of said current or alternatively in accordance with the variations in the rate of change of magnitude of the current (using Fig.3 circuit in combination with Fig. 1). The audio signal is fed to ear phones whereby an operator is warned immediately of the presence of a leak as a probe 54, directing the tracer gas, scans the said surface. The ion current can either increase or decrease in response to a leak depending on whether the tracer gas is more or less readily ionizable than the gas normally present in the system 50. Instead of using the probe nozzle 54 there may be a tube, surrounding the vacuum system, having a plurality of gas emitting nozzles directed toward the system, and gas may be emitted sequentially therefrom in a programmed sequence. In the amplitude frequency converter circuit Fig. 1 (not shown) the audio signal is produced by controlling the charge and discharge rate of a capacitor (1) in series with the ear phones, the ionization current magnitude being used to change the state of (switch on and off) transistors which are effectively in parallel with the capacitor, thereby providing a relaxation oscillator the frequency of which is dependent on the amplitude of the input signal from the sensor. The claims are directed to the amplitude/frequency converter circuit. (See class H4L).

Relaxation oscillator having stable pulse width

Abstract: An oscillator in which the timing capacitor is discharged through the main conduction path of a programmable unijunction transistor via the output circuit of a current mirror amplifier. The linear discharge voltage thereby obtained may be employed to drive the emitter-base junction of a transistor amplifier to obtain output pulses of relatively uniform width.

Scanning capacitance microscopy using a relaxation oscillator

Abstract: We have performed scanning capacitance microscopy using a relaxation oscillator. Precision calibrations indicate a sensitivity on the order of 0.05 pF. Surface topography of metallic structures, such as machined grooves and coins, can be readily obtained either in the constant-height (non-contact) or tapping (contact) mode. Spatial resolution of less than 50 μm has been achieved. Our simple, low-cost system can be a valuable platform in the undergraduate laboratory, providing students with experience in microscopic imaging techniques.

Switched-mode power supply for a DC motor

Abstract: Switched-mode power supply for a low-voltage DC voltage motor 8 having a flow-through converter, the power part of which contains a switching transistor 1, a rectifier diode 9 and a transformer 2, the primary winding 21 of which is connected in series with the switching path of the switching transistor 1 and the secondary winding 22 of which is connected in parallel with the series connection of the rectifier diode 9 to the DC motor 8, a freewheeling diode 10 being arranged in parallel with the DC motor 8, the control device of the converter being used for driving the switching transistor 1. The control device contains an astable multivibrator 3 which determines the duty ratio of the switching transistor 1, and a comparator 4 with hysteresis and has the voltage across the DC voltage motor 8 applied to its input side, the output signal of which comparator is delivered at an earlier instant in the event of increasing motor voltage. The outputs of the astable multivibrator 3 and of the comparator 4 with hysteresis are connected to the control terminal of the switching transistor 1 via a logic (switching) element 5.