SU1264093A1 - Frequency comparing device - Google Patents

Abstract

The invention relates to the field of electrical measurements and can be used to control the frequency of electric machines. The purpose of the invention — extending the functionality of the device — is achieved by expanding the range of variation of the monitored frequencies. For this, the device additionally introduced two elements, And 2 and 3, and new inter-element links. The drawing also shows a 1K-trigger 1, an RS-trigger 4. The device can be used in automatic control systems of AC electric generators as a rotational speed meter, in computing technology can be used as a device for subtracting either frequencies. 2 Il. (L

Description

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The invention relates to the field of electrical measurements and can be used to control the frequency of electrical signals.

The purpose of the invention is to expand the functionality of the device by expanding the range of change of the control frequencies.

Figure 1 shows the functional diagram of the proposed device; figure 2 - timing charts of his work.

The device for comparing frequencies contains a 1K-trigger 1, the first 2 and the second 3 elements And and the RS-trigger A.

The first input of the first element And 2 is connected to the 1-input of the 1K-flip-flop 1 and is the first input of the device, the second input of the first element And 2 is connected to the direct output of the 1K-flip-flop 1.

The first input of the second element And 3 is connected to the K input of the 1K-flip-flop 1 and is the second input of the device, the second output of the second element And 3 is connected to the inverse output of the 1K-flip-flop 1.

The output of the first element And 2 is connected to the S-input of the RS flip-flop 4 and is the first output of the device. The output of the second element 3 is connected to the R-input of the RS-flip-flop 4 and is the second output of the device, the third and fourth outputs of the device are the direct and inverse of the RS-flip-flop 4, respectively

The frequency comparison device operates as follows. ;

Suppose that the 1-input trigger receives pulses of a higher frequency f (Fig. 2a corresponds to point A in Fig. 1), and the K-input receives pulses of a lower frequency f (Fig. 26 corresponds to point B in Fig. 1) and fj several times more i Between two rows of spaced pulses fj are located, say, four pulses fj (section ON in FIG. 2).

The first pulse f, transfers the trigger 1 to a single state at the direct output (FIG. 2B corresponds to point B in FIG. 1). With some delay relative to the front of the first pulse, a single signal arrives at the second input of the element I 2 and opens it. The second pulse fj passes through the element And 2 (Fig.2d corresponds to the point D on

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Fig. 1), and entering the S-input of the trigger 4, switches it to a single state at the forward output (Fig. 2e corresponds to point E in Fig. 1). 5 The signal at the output of the device will be f, f ,.

Since the impulse from the direct output of the trigger 1 (figv) enters

About the second input element And 2, then it allows the passage of pulses f 1 (arriving at the first input element And 2), starting with the second (first, pulse f, not

tS passes through AND 2, since the enabling pulse from the direct output of trigger 1 arrives at AND 2 with a delay). Pulses f, will pass through the element And 2 before the end of 20 or pulse trigger 1 (Fig.2B), i.e. before the second pulse f (Fig. 26) arrives, which sets trigger 1 to the zero state at the direct output (Fig. 2c). The number of pulses fj passing through an element And 2 during the time of action is allowed B (its pulse at the direct output of flip-flop 1 is one less than the number of pulses arriving

30 per 1-input trigger 1 for the time interval between two rows of located pulses fj (Figure 2d),

In the next frequency comparison cycle (section NP), the first pulse, f, again triggers trigger 1 into a single state (Fig. 2c). Then the above picture is repeated.

Thus, the four pulses f arriving at the 1-input of the trigger 1, and one pulse fj arriving at the K-input of the trigger 1, gives three pulses from the output of the And 2 element, i.e. differential frequency

Figure 2 also shows the mode when the frequencies f and fj are equal (PR section). In this area, the pulses fj and fj alternate in time. The device at the output saves the previous state. In this case, the corresponding f; fj (Figure 2e).

Claims (1)

The device also works in the same way with fj f-i (section RS in FIG. 2). In this case, the difference frequency signal is removed from the output of the IZ element, and the first pulse of this frequency sets the trigger 4 to one state at the inverse output. 3 Thus, the proposed device, as follows from the algorithm of its operation, allows the comparison of frequencies without restrictions on the range of variation of their values, which expands its functionality. Invention A device for comparing frequencies containing a 1K flip-flop and an RS flip-flop characterized by that, in order to expand its functionality, two AND elements are introduced into it, with the first input of the first element AND connected to the 1 input of the 1K flip-flop and the first srig2 93 device input, and the second input of the first element I is connected to the direct output of the 1K flip-flop, the first input of the second element I is connected to the K-input of the 1K-flip-flop and is the second input of the device, and the second input of the second element M is connected to the inverse output The 1K flip-flop, wherein the output of the first element I is connected to the S-input of the RS flip-flop and is the first output of the device, and the output of the second element I is connected to the R-input of the RS-flip-flop and is the second output of the device, the third and fourth outputs of which are respectively direct and inv Nerskny RS outputs - trigger p. a.