Oscillators – Solid state active element oscillator – Transistors
Patent
1982-08-26
1985-01-22
Grimm, Siegfried H.
Oscillators
Solid state active element oscillator
Transistors
331143, H03K 3023, H03K 408
Patent
active
044954760
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a sawtooth voltage generator which is particularly switchable as a clock and reference voltage generator of an electronic regulation means for a motor vehicle heating system.
BACKGROUND
A sawtooth voltage generator has already been proposed, in which the output voltage is picked up at a capacitor which could be charged via a first resistor of low resistance and discharged via a second resistor of higher resistance and with a longer time constant. The result is the equivalent of two RC circuits or members, in which the capacitor, i.e. the C member is the same for both circuits, but the resistors, i.e. the R members were different. The first RC circuit, upon charging the capacitor, determines the leading edge; the second, or further RC member, upon discharge of the capacitor, the trailing edge of the sawtooth voltage. This sawtooth voltage generator thus had a very steeply rising leading edge of the sawtooth voltage because of the low-resistance charging resistor, and thus the clock time was determined almost exclusively by the discharging time constant of the discharging circuit of the capacitor.
THE INVENTION
It is an object to provide a sawtooth wave generator in which the frequency or repetition or cycling time of the sawtooth wave is selectable independently of the wave shape of the sawtooth wave.
Briefly, two capacitors are provided, connected to a common charging circuit which is of low resistance, so that the two capacitors are, effectively, rapidly and practically instantaneously charged to a predetermined charge voltage. A first one of the capacitors is connected to a discharge circuit which includes a resistor, the discharge circuit resistor, in combination with the capacitor, defining the time constant or timing or frequency of the sawtooth wave generator. The second capacitor is discharged by an independent discharge circuit, decoupled from the first discharge circuit, for example through a second resistor which may well have a value differing from the first, and to a voltage level which may differ from that of the first, for example being somewhat higher. The wave shape of the second capacitor-resistor discharge circuit then may well differ from that of the first; yet, the cycling time is governed by the first. The wave shape of the discharge circuit is derived, for example, from across the second capacitor. The second capacitor cannot, however, resume a charging cycle until the first capacitor is completely discharged so that, regardless of the discharge wave shape of the second capacitor, the cycling time or frequency of operation of the sawtooth generator is determined by the first capacitor--first discharge resistor network.
The sawtooth voltage generator has the advantage over the prior art that the shape of the curve of the trailing edge can be adjusted independently of the cycling or clock time of the generator. This curve form is variable within wide limits tending in the direction of greater curvature, and the dimensions of the circuitry components are entirely uncritical. A steady curve course can be obtained, without sharp bends. The trailing edge can have a substantially freely selectable nonlinearity, which can be utilized for attaining particular effects in a subsequently disposed regulating apparatus.
The sawtooth voltage generator according to the invention is particularly suitable for use in an electronic heating regulation means, as a clock generator and reference voltage generator for the pulse-width modulation of an output signal. With previously known circuits in sawtooth voltage generators for this purpose, it was not possible to exert notable influence on the curve form of the sawtooth voltage, yet it is necessary to do so when such a generator is used in an electronic heating regulation apparatus, in order to generate a suitable nonlinearity of the trailing edge of the sawtooth voltage so as to compensate for the nonlinearity of an adjusting member used. Non-linearities of a heat exchanger and a hot-water valve are compensated by this circu
REFERENCES:
patent: 3185889 (1965-05-01), Attwood
patent: 3678332 (1972-07-01), Boekhorst
Vazhenina, "Sawtooth Voltage Generator With Correcting Circuits", Telecommunications and Radio Engineering, vol. 27, No. 4, Apr. 1972, pp. 120-122.
Grimm Siegfried H.
Robert & Bosch GmbH
LandOfFree
Sawtooth voltage generator does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sawtooth voltage generator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sawtooth voltage generator will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-568745