DE1763759C - Differential comparator for alternating voltages - Google Patents

Description

For all control or monitoring tasks where the control or monitoring variable is a AC voltage or an alternating current. z. B. at the pilot monitoring in carrier frequency systems, a voltage comparator or a voltage discriminator is used needed, which when reaching a certain amplitude of the alternating voltage at his Output emits a voltage priming. As a benchmark only a direct voltage is suitable for the voltage comparator because it is generated by reference diodes with sufficient quality and stability can be produced. As a comparison amplifier Differential amplifiers are particularly suitable, especially if they are integrated. They are cheap, stable, Largely independent of temperature, very empathetic and have very large reinforcement.

Differential amplifiers have two equally sensitive inputs, one invading and one non-inverting Input. If the voltage at the inverting input exceeds that at the non-inverting input Input mn a few mV, so the output voltage makes a jump downwards, exceeds the Voltage at the non-inverting input

3 4

at the inverting input by a few mV. so makes the rectification is easier because the requirement

the output voltage a jump upwards. the smoothness of this output voltage is low

F.s is known and common, which are to be monitored. Because this tension only has to be digital

Rectify alternating voltage and make the yes-no statement received.

DC voltage to be compared with the reference voltage.

same. The reference voltage is stronger at the one has a certain dynamic range between

Input and the rectified, to be monitored one minimum value and one maximum value.

Voltage a :: the second input of the DilTerenzver- If the reference voltage is applied to the inverted

stronger applied. Such a circuit is specified generating input and the AC voltage to the

in: " The applications of linear microcircuit" from i "non-inverting input, then the output

SGS Fairchild, Second Issue. August 1% 7. Page 106 voltage the minimum value if the alternating peak

and 107th voltage is less than the reference voltage. He-

On the basis of this state of the art, the alternating tip span refers to the value of the si. If the invention is therefore based on a differential reference voltage, short needle-point noises occur for alternating voltages for use in control pulses of maximum value amplitude. and training scarfs. in particular for the L. one applies the reference voltage to the not Fiiotüberwaehun "in carrier frequency systems. the inverting input and the AC voltage when the change-inverting input reaches a certain amplitude, the output has ! cisvoltage at its output has a voltage voltage the maximum value, called the alternating peak jump outputs and at least one differential voltage is 20 lower than the reference voltage. contains more, which contains the to be monitored or re- If the alternating peak voltage reaches the value of If there is an alternating voltage with a reference direct reference voltage, short needle-point voltages occur compares. irmulse of the minimum value amplitude.

This method has several fundamental disadvantages.

tcile. First, the rectified voltage of the rators of the invention is inherent in FIG. 1 to 5.

AC voltage not proportional, because the DC In Fig. I En is the non-inverting input,

judges have a threshold voltage that is overcome Ei the inverting input of the differential amplifier

v.crden must. Second, the AC voltage must be kers DV. Terminal K 1 is the earth terminal. Between

be relatively large so that you can see the swell, tension -Jes see the Klemmer; Kl and KX is a positive

Rectifier can overcome. Third is the 30 voltage - VB \. Between terminals K 3 and

Voltage comparison incorrect because the rectifier KX has a negative voltage - UBl. A is the

have a relatively large temperature coefficient. Output terminal of the divergence amplifier. A

Fourth, the rectified voltage must be careful evaluation transistor Ts of the npn type is via a

so that the differential amplifier voltage divider RvIRb from output A of the DitTe-

emits a defined output voltage. 35 reference amplifier controlled in such a way that the square

The invention is therefore based on the object of briefly bypassing impulses (needle tip impulses) the evaluation trans! - the rectification of the alternating disturbance to be monitored from the blocked to the conductive application voltage and transferring a direct comparison. If the collector-emitter converter for alternating voltages is used in control, this evaluation transistor is parallel to the capacitor and monitoring circuit. In particular to create 40 torC of a pilot monitoring applied to the battery voltage ÜB 1 in carrier frequency systems to create a series connection of a resistor R and one that is switched when a certain ampli-capacitor C is reached, the transistor becomes conductive when the alternating voltage is periodic at its output The capacitor C emits a voltage jump and discharges a differential amplifier, and the capacitor voltage cannot contain any values that can assume large values for the AC voltage to be monitored. Only when the voltage is blocked is compared with a RclVenz equal voltage. sistor, the capacitor C can be fully charged

Be: the dilference comparator described above. The differential voltage (/? Is used between the

To solve this problem, terminals Ei and KX and the about ·. ¹ aching

suggested that at one input of the DiITe AC voltage Hw between the terminals En

reference amplifier and applied to the so and KX .

The other input is the one to be monitored or regulated. If the circuit of FIG ; in this case the output voltage of the DüTerenz-Wechselspit / euspannunü no output signal occurs, 55 amplifier iv only. the transistor Ts is blocked and the capacitor C charged during the transfer. If the reference voltage is to be monitored above a square or level limit, the alternating voltage exceeds the needle-pulse-shaped output voltage of the same frequency. the result is a positive needle · (| iicn / how the alternating voltage occurs, which after peak pulses that make the transistor 7'.v short-term rectification to control an evaluation code, and the capacitor Γ is discharged. The circuit can be used Circuit according to 1 · "i g. I for monitoring

Integrated differ'- 'i / verslarkers are so sensitive. of a sublevel ·; is used, the setpoint value

that an alternating voltage of a few mV to the alternating voltage is greater than the reference voltage

Controlling the DilFcreiv / .veistärkers is sufficient. Be with; at the same time, the initial span fluctuates de :. DiI-

of the application de ;: DilTerenzkomparators after the 65 reference amplifier rectangular between small

Invention for pilot monitoring in Ί "riigerfrei. | Uenz- and large values, the transistor Ts is always

systems, the required gain of the pilot can be conductive and the capacitor C is discharged,

receiver some Neper are kept smaller. At the level limit to be monitored, the exceeds

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Comparative voltage the alternating voltage, the output and this inverting stage must be parallel to the output

The output voltage of the diluter amplifier becomes small, the capacitor of the other circuit is

the transistor Ts is blocked and the condensate.

toi Γ charged. I- "i g. 5 /. Shows an embodiment of a dcr-

Are in the circuit according to F i g. 1 the appropriate circuit for the monitoring of the over and over swap in such a way that the comparison spanniing Unlerpcgels, whereby the upper part with a difference / wipe the terminals En and K \ and those to be re-amplified DV 1 with the F. input terminals Ei 1, monitoring alternating voltage between the terminal / wil, the output terminal A 1, the comparative voltage Ei and Ki is applied, the uimg (, / # 1, the alternating voltage UwI, an off circuit does not work value transistor Ts 1 and a series circuit RM greater than the alternating voltage, so the output f'l for monitoring the overpcgels and the lower voltage of the dilution amplifier is large, the tran part with a differential ^{amplifier / M 7} 2 with the FJnsistor Ts conductive and the Discharge capacitor C. Input terminals Ei 1, En 2, of the output terminal A 2, on the other hand, if the alternating voltage is greater than the Vcr- of the direct voltage (Vg 2, the direct voltage of the alternating voltage, the Au fluctuates output voltage 15 UwI, an evaluation transistor 7'.v 2, a series of the differential amplifier rectangular between circuit R HC1 and a phase reversing transistor small and large values, the transistor '/'.? 7 is ".v3 whose base likewise to the condenser Cl connected to the tap of a parallel always conductive and the capacitor C voltage divider lying if discharged. R 3 / R 4 and whose Kollcktor-limittcr-Streckc

According to FIG. 2 is connected in parallel to capacitor C 1 through 20,

Interposition of a phase marked U is used to monitor the under-level

reversing transistor between the output A of the Dif- will. The comparative spanniing Ug 1 of the upper

fcrcnzstarkcrs and the evaluation transistor Ts circuit part corresponds to the upper limit of the

be bypassed. Monitoring areas. The DC voltage

If, as shown in Fig. 3, the base of the training "5 Ug 1! Rs lower SchalUingsteücs the untcwertctransistors corresponds via a voltage divider to a ren border of the monitoring area. The Ausfeste voltage is applied and the output voltage is output signal from the capacitor C! the upper of the differential amplifier removed from the emitter of the evaluation circuit.

transistor fed, this is how the circuit works. If the target pcgel prevails, the transistor Ts is 1

Likewise. ~ 3o blocked, the transistor Ts 2 conductive and the tran-

If, according to FIG. 4, an evaluation transistor is blocked by the sistor7'j3. The capacitor C 1 is on the

PNP type is used, which charges its control voltage between voltage UB 1.

see the terminals A and Kl taps, so function- If over-level occurs, it is, as described above,

The circuit does not work even without phase reversal, the evaluation transistor Ts 1 through the Rcchl-

sturgeon. Thereby, between output A of the differential pulse (needle point pulse) is repeated again and again

Reference amplifier and the base of the evaluation transistor made conductive, the capacitor C 1 is discharged

a Zcnerdiode D switched to the potentials and an alarm is triggered. The transistor remains

to fit. 7 * 5-2 conductive and the transistor Ts 3 blocked, so that

If the level of an alternating voltage is too high or too low, the lower circuit does not control the output voltage

To be monitored, two switches 40 must be influenced.

tungcn according to FIG. 1 can be used. When the level occurs, the voltage is zero and the capacitor C 2 is charged, as was the case with a circuit above, the capacitor C 2 is charged, the other circuit, the voltage transistor Ts 3 via its voltage divider UB 1 at its output capacitor. Should over- R 2> IR 4 controlled so that it becomes conductive and the level and lower level a uniform output signal 45 capacitor C 1 discharges. The transistor continues to occur, so one of the two circuits behind Ts 1 must be blocked and it does not affect the output voltage of the rectification in a phase inversion stage.

1 sheet of drawings

Claims (10)

Patent claims: 1. Differential comparator for alternating voltages for use in control and monitoring circuits, especially for pilot monitoring in carrier frequency systems. which emits a voltage jump at its output when a certain amplitude of the alternating voltage is reached and contains at least one differential amplifier which represents the alternating voltage to be monitored or regulated with r ^; ner DC reference voltage compares, characterized dauurch that to the one input of the differential amplifier (DV) the reference voltage (Ug), and both voltages with each other such ver _o is the applied directly to the other input to be monitored Wechselspannu 1> (Uw) nd leichbar are that if the reference voltage predominates over the alternating peak voltage, no output signal occurs, while if the alternating peak voltage predominates over the reference voltage, a square-wave or needle-pulse-shaped output voltage of the same frequency as the alternating voltage occurs, which can be used to control an evaluation circuit after rectification. 2. DifTerenzko.nparator according to claim .1. wherein the differential amplifier (P '/) transistors includes npn type and is called the reference voltage (Ug) to the inverlierenc' η input and which is applied to be monitored alternating voltage (Uw) at the non-inverting input (En) (E /) is characterized in that a Auswertetransistor (tO type npn obtained from the on Massepotentia! (terminal Kl) output voltage of the differential amplifier (DV) via a base voltage divider (Rv / Rb) between base and emitter is controlled such that it becomes conductive when the output voltage of the differential amplifier is high, and is blocked when the output voltage of the differential amplifier is low (Fig. 1). 3. Differential comparator according to claim 2, characterized in that the collector-emitter path of the evaluation transistor (Ts) is connected in parallel to the capacitor (C) of a WC series circuit (R / C) connected to the operating voltage (UBl) of the differential amplifier. 4. Difference comparator according to claim 3 for monitoring an excess level in the pilot monitoring, characterized in that the setpoint alternating peak voltage is smaller than the reference voltage and, at the setpoint, the Ausganyskondensator '(C) the circuit is charged. 5. DifTerenzkomparator according to claim 3 for monitoring a sub-level in the pilot monitoring, characterized in that the setpoint alternating peak voltage is greater than that Reference voltage and at setpoint the output capacitor (C) of the circuit is discharged. 6. DifTerenzkomparator according to claim 1, wherein the reference voltage is applied to the non-inverting input, characterized in that between the output (A) of the differential amplifier (DV) and ilen Aiissvcrtelransistor (7'.v) a phase inverter (U) connected iM (Fig. 2). 7. DifTerenzkomparator according to claim I, in which the differential amplifier contains transistors of the npn type and in which the reference voltage is applied to the inverting input and the alternating voltage to be monitored is applied to the non-inverting input, characterized in that an npn transistor as an expansion transistor (Ts ) is used. which receives its base voltage via a fixed voltage divider and whose emitter is supplied with the output voltage of the differential amplifier (Fig. 3). S. DifTerenzkomparator according to claim 1, in which the differential amplifier contains transistors of the npn type, and in which the reference voltage is applied to the non-inverting input (En) and the alternating voltage to be monitored is applied to the inverting input (E /), characterized in that a pnp transistor is used as an evaluation transistor (Ts) . which taps its control voltage between the output terminal (/ 1) of the differential amplifier (DV) and the positive potential of the operating voltage of the differential amplifier terminal K 2 (FIG. 4). ⁽ ). Differential comparator according to Claim X, characterized in that a Zener diode (D) is connected between the output (A) of the differential amplifier (DV) and the base of the evaluation transistor (Ts) (FIG. 4). 10. DifTerenzkomparator according to one of claims I to 3 for monitoring both the excess level and the lower level of an AC voltage, characterized in that a circuit (DKl, T.?l) for monitoring the excess level according to claim 4 and a circuit (DV 2, Ts 2) are connected in parallel for monitoring the lower level according to claim 5 and that the latter euie phase reverser stage (Ts 3) is connected downstream, the collector-emitter path of which is connected in parallel to the output capacitor (C 1) of the circuit for monitoring the over level (Fig. 5 ).