Indicator of deviations of mains voltage

At a food of some radio equipment from a network of an alternating current it is necessary to watch stability of its tension and at a tension deviation over admissible norm either to disconnect equipment, or to change tension on it, for example, by means of the autotransformer. For the alarm system of deviations of mains voltage it is possible to use the offered indicator (see fig.) executed on three light-emitting diodes and two dinistor.

Feature of the device is turning on of indicators (light-emitting diodes) at each positive half-cycle of mains voltage, but only at its certain amplitude equal to a threshold of operation, and switching off at decrease in instant value of tension to zero. It excludes a hysteresis and increases accuracy of indication.

the Indicator can be included alt both in the network socket, and in the autotransformer socket. On an entrance of the indicator there is a tension limiter from the VD1 diode and VD2 stabilitron, and after it three in parallel included chains of indication follow. The first of them, consisting of the R1 resistor and HL1 light-emitting diode, is intended for indication of existence of mains voltage. Other chains consisting of dividers of tension, threshold devices on dinistor and the light-emitting diodes included consistently with them, are intended directly for indication of deviations of tension. The variable R3 resistor establish the bottom threshold of operation when mains voltage will fall, say, to 5 %, to a R5 - the top threshold when tension will increase on as much.

If mains voltage in norm, burn HL1 and HL2 light-emitting diodes. At tension fall the light-emitting diode of HL2 dies away, and HL1 continues to be shone. When tension increases, all light-emitting diodes burn.

to Adjust the indicator it is most convenient with the autotransformer on which exit it is possible to establish the necessary tension, and variable resistors to regulate a threshold of inclusion of the corresponding light-emitting diodes. If at the lowered tension the light-emitting diode of HL2 does not die away, it is necessary to increase resistance of the R2 resistor. Having strengthened variable resistors on the obverse panel of a design and having supplied them with an otgraduirovanny scale of thresholds of operation of this or that light-emitting diode, the indicator can be used for the most various purposes.

of Century БУТЕВ, Donetsk, RADIO of 6-1985 g, c.39.

/>/>/>/>/>/>/>!>