SU1688178A1 - Device for checking electrical chains and voltages - Google Patents

Abstract

The invention relates to the field of electrical, triple measurements and can be used for prompt adjustment and repair of electrical equipment, household electrical appliances, etc. The purpose of the invention is to increase noise immunity by eliminating false voltage indications from controlled EMF induced by electromagnetic fields. and also simplify the device. The device contains an amplifier with indication of the presence of an external circuit, made on a transistor 13, a LED 9 and resistors 12 and 14, a power source 10 and two high and low voltage indication circuits. The high voltage indication circuit contains a LED 7, a zener diode 6, a resistor 4. A low voltage indication circuit contains an LED 8, a resistor 5. The device also contains two input terminals 1 and 11, an input circuit containing a resistor 2, a diode 3, 1 or less.

Description

The invention relates to the field of electrical measurements and can be used for quick adjustment and repair of electrical equipment, household electrical appliances, etc.

The purpose of the invention is to improve the noise immunity by eliminating false indications of the induced EMF in the monitored EMF circuits and simplifying the device.

The drawing shows an example of a circuit diagram of a device for monitoring electrical circuits and voltages implemented on a pn-conduction transistor.

The device for monitoring electrical circuits and voltages contains the first input terminal 1, which is the first input of the device, which through the first additional resistor 2 is connected to the anode of diode 3, the cathode of which is connected to the first terminals of the second and third additional resistors 4 and 5, the second terminal of the second additional resistor 4 is connected to the cathode of the Zener diode 6, the anode of which is connected to the anode of the second LED 7, the cathode. This is connected respectively to the cathode of the third LED 8, the anode of the first LED 9, the output + power supply 10 and the second input terminal 11, which is the second input of the device, the second output of the resistor 5 is connected to the anode of the third LED 8 and the second output of the resistor 12, the first output of which connected to

ABOUT

with

00

 oo

In the transistor 13 and in the first terminal of the resistor 14, the second terminal of which is connected to the emitter of the transistor 13 and the output of the power source 10.

The device works as follows.

In the initial state, when the input terminals 1 and 11 are not closed, the LEDs 7-9 are not hot, since the LEDs 7 and 8 are turned on opposite to the power source 10, and the LED

9- due to the closed transistor 13. With the closure of terminals 1 and 11 to a working monitored circuit, plus a power source

10 across the circuit: terminals 1 and 11, external circuit, resistor 2, diode 3, resistors 5 and 12 enter the base of transistor 13 and open it. At the same time, LED 9 lights up indicating the presence of an external circuit.

When the device is connected to an alternating current source of low voltage (0 10-100 V), the half-period applied by plus to terminal 11 is blocked by diode 8, and the half-period applied by plus to terminal 1 of the circuit: terminal 1, resistor 2, diode 3, the resistor 5, the LED 8, terminal 11, lights the LED 8, indicating the presence of voltage, and through the resistor 12 opens the transistor 13 - the LED 9 is lit. The high voltage indicator, the LED 7, does not light up, since not enough for the stabilitron 6 This p-n junction of the LED 8 blocks the transistor 13 from the voltage applied to the terminals 1, 11, since the base current of the transistor 13 cannot exceed the value defined by the formula

b

Tsi.p. f U R2

etc

where 1e is the base current of the transistor 13;

W.p. supply voltage 10;

Unp. - direct voltage drop across the pn junction of LED 8;

R2 is the resistance of the resistor 12.

When controlling high voltages (U 100-400 V), the increased current creates a voltage drop across the resistor 5, which is sufficient for the breakdown of Zener diode 6, while, in addition to LEDs 9 and 8, LED 7 lights up indicating a high voltage. The current leveling resistor 4 is required to distribute the current in the parallel branches of the LEDs 8 and 7.

Thus, the p-transistors of diode 3 and LED 8 block the amplifier, made on the transistor 13, from both polarities of the monitored voltage. For

DC voltage control minus must be applied to terminal 11, plus to terminal 1. The circuit is indicated by one LED 9, low voltage by two 8 and 9, high by three 7, 8 and 9. Significant input current determined by the current of LEDs indicators, and the optimum sensitivity, provided by a single-cascade transistor amplifier, protects the device from false indication

induced emf. Separate indication of a series of low (12, 24, 36, 48, 60 V) and a series of high (110, 127, 220, 380 V) voltages creates convenience in operation and expands the scope of application,

Claims (1)

Invention Formula A device for monitoring electrical circuits and voltages containing a source power supply, the transistor, the collector of which is connected to the first output of the first LED, the second output of which is connected to the first output of the power source, the base of the transistor through the bias resistor is connected to its emitter and to the second output of the power supply, the current limiting resistor, one output of which is connected to the base of the transistor, Two input terminals, which are connected to the circuit, in order to increase the noise immunity and simplify the device, two LEDs, a zener diode, a diode and three additional resis ora, the first additional resistor is connected between the input terminal and the second output of the diode, the first output of which is connected to the first outputs of the second and third additional resistors, the second output of the second additional resistor is connected to the first output of the Zener diode, the second output of which is connected respectively to the second output of the second LED, the first output of which is connected respectively to the first output of the third LED, the second output of the first LED and the second input terminal, the second output of the third additional resistor is connected to the second output of the third LED and the second output of the current-limiting resistor. L 1 "-Izk D-O  Yu