Relaxation oscillator

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

Oscillator circuit for surface wave filter

Abstract: An oscillator (in particular for the MHz/GHz range) composed of a surface wave filter (21) with three converters has an oscillator voltage of very pure frequency. In particular, a filter with minimum cross-talk is used. One converter (22) acts as input converter and two converters (23, 24) act as output converters.

Automatic gain control circuit and method and super-regenerative RF receiver

Abstract: An automatic gain control (AGC) circuit is applied to control a margin voltage of an oscillator The margin voltage is the voltage difference between a high-level output and a low-level output of the oscillator The AGC circuit of the present invention includes a comparator and a processing unit Wherein, the comparator compares the margin voltage of the oscillator and a reference voltage Based on the output of the comparator, the processing unit outputs a ripple code to determine the value of a driving current output from a current generator The oscillator generates an oscillation output to the comparator based on the driving current

Improvements in or relating to circuit arrangements for providing a stabilized d.c. output

Abstract: 779,162 Automatic voltage control systems MULLARD RADIO VALVE CO, Ltd Sept 23, 1955 [Oct 11, 1954; Jan 18, 1955], Nos 29301/54 and 1514/54 Class 38 (4) In a system of the kind in which the output of a transformer-coupled transistor relaxation oscillator is rectified to provide a DC supply, the DC output voltage is stabilized by controllers the base emitter potential in accordance with a voltage derived from an auxiliary winding on the transformer In one embodiment the transistor 1 together with transformer windings 6, 8 and low-voltage supply from a relaxation oscillator as disclosed in Specification 763,445 and the high-voltage pulses induced in winding 6 when the oscillator cuts off are rectified at 10 to supply a load 12 The amplitude of oscillation is determined by the bias voltage across a resistor 19 in the base/emitter circuit of transistor 1 Resistor 19 is also included in the base/collector circuit of a transistor 14 to the emitter of which is applied a portion of the oscillator voltage obtained from an auxiliary winding 13 and a reference voltage 18 Then if the emitter becomes more positive than the base due to a rise in oscillator voltage, the transistor 14 conducts and produces a positive bias for the base of transistor 1 In a modification, Fig 1, of the drawings accompanying Provisional Specification 1514/55, the highvoltage DC load is supplied from a separate winding 14, and the output of the control winding 13 is rectified at 15 and compared with a reference voltage 16 to provide the bias across resistor 19 in the base/emitter circuit of the oscillator transistor 1 In a further modification, Fig 2 (not shown), the reference battery 16 is omitted Specifications 771,003, [Group XL (c)] and 771,451 also are referred to

Improvements in or relating to circuit arrangements for providing a d.c. output

Abstract: 776,308. Rectifying. MULLARD RADIO VALVE CO., Ltd. Dec. 8, 1955 [Jan. 18, 1955]. No. 1515/55. Class 38 (2). An E.H.T. generator comprises a relaxation oscillator employing a junction transistor together with means for preventing the output voltage from exceeding a predetermined value. When the voltage from a D.C. source such as a battery 5 is suddenly applied to a junction transistor 1 the transistor will conduct and allow current to flow through the primary winding 6 of a transformer 7. The increasing current through this winding produces a negative voltage at the end of a secondary winding 8 which is connected to the base 3 of the transistor thereby causing sufficient emitter-base current to flow to make the voltage drop between the collector 4 and emitter 2 of the transistor very low. Thus substantially the whole of the applied D.C. can be regarded as applied to the primary winding 6 thereby producing a linear rise of current therein and hence a constant voltage across the secondary winding 8 with the result that a certain, constant base current flows, corresponding to which current the transistor will have a relevant curve in its collector-current versus collector-voltage characteristic. When the collector current reaches the knee of this curve the voltage across the transistor rises and thus there will be a reduction in the rise of the collector current. Because of the transformer 7 the base current will now decrease causing a further decrease in collector current whereupon a positive voltage is generated in the secondary winding 8 thus cutting off the transistor. A large voltage will appear across a further secondary winding 13 of the transformer 7 which voltage is rectified by a rectifier 10 and applied to a load 12. At the end of the decay period the transistor 1 reconducts and the cycle repeats so that the circuit is self-oscillating. The energy taken from the D.C. source is substantially constant, thus the voltage across the load will be dependent upon the magnitude thereof. To confine this voltage to a predetermined value a neon tube 14 is arranged to ignite at this predetermined value so that current will flow through resistors 9, 15 whereby a positive voltage will be applied to the base 3 of the transistor causing the transistor to be cut off. The positive voltage so produced will now decay and the neon tube will be extinguished. By judicial choice of the values of the condenser 11 and the resistors 9, 15, the time constant will be such that the oscillations will not recommence. In order to restart the oscillations the transistor must be shockexcited, for example by the removal and sudden re-application of the D.C. supply 5. In an alternative arrangement the neon tube may be replaced by a gas discharge triode, by the use of which adjustment of the predetermined voltage which is applied to the load 12 may be made. Specifications 769,445 and 771,003, [Group XL (c)], are referred to.