JPH10206471A - Electroscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable detection of presence absence, kind, polarity and conduction of input electric power without changing over voltage by using a constant electric current circuit for a detecting section. SOLUTION: When voltage is applied to set a probe 1 to (+) and an earth ring to (-), electric current flows between the base and emitter of a TR 6 through a constant electric current circuit consisting of a FET 4 and resistance 5 and returns through a diode 8 to the earth ring 2. Then, a LED 7 (1/2 R) radiates light through a dry cell 12 by the conduction of the TR 6. When voltage is applied to a probe 1 and earth ring 2 so that both are set respectively to (-) and (+), a TF 11 is made conductive through a FET 9 and resistance 10 and returns to the probe 1 through a diode 3. The LED 7(1/2 G) radiates light through the conduction of the TF 11. Also, in the application of AC voltage, the LED 7 (1/2 R) and LED 7 (1/2 G) radiate light alternatively. When voltage is absent between the probe 1 and earth ring 2, the LED 7 does not emit light. The presence absence, kind and polarity of the input electric power can be detected from the state of emission of light.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for checking an electric circuit and the like to determine the presence or absence of a voltage. It relates to a voltage detector for checking continuity.

2. Description of the Related Art As a conventional voltage detector, there are. In some cases, the presence or absence of voltage is checked by blinking a light bulb or neon tube.

[0003] Of the light bulb type described in the prior art,.
Due to the characteristics of the light bulb, the brightness may change due to the high and low detection voltages, and the filament may be broken at a voltage higher than the standard. The range of the detection voltage is limited.

[0004] Since the internal resistance of the electric bulb is very small, when the electric bulb is connected to the electric circuit to be inspected for the purpose of electric detection, the influence on the electric circuit to be inspected is large.

[0005] In the case of power detection, it is necessary to bring both ends of the filament of the electric bulb into sufficient contact with the circuit to be detected.

[0006] In the case of a neon tube type, due to its discharge characteristics. Only relatively high voltage measurements can be made. Since the discharge current is very small, the influence on the circuit under test is small. The ground return can be used in place of human body resistance.

[Problems to be Solved by the Invention] The bulb type described in the prior art. Both neon tube types have a very simple structure, but are very convenient depending on the purpose of use. So reproduce only the good parts of both. A variety used in many industries as of today. It can be used commonly for inspection of various electric circuits. Aiming to manufacture a convenient electrometer.

It can be used without switching anything from low voltage to high voltage

The usable frequency band is sufficiently wide.

AC. DC. In the case of direct current, the polarity is also displayed so that it can be understood.

The ground return can be replaced by the resistance of the human body.

A continuity test using a very small current can be performed.

It can be manufactured to the size of an office ballpoint pen. An object of the invention is an electric detector.

[Means for Solving the Problems] To achieve the above object. The detector of the present invention uses a constant current circuit for the detection unit. Convert a wide range of input voltage to a certain amount of current. The display was driven.

The constant current circuit is composed of a gate of a field effect transistor. It is formed by applying an appropriate bias voltage between sources. Since the characteristics can be changed by setting the bias voltage, if the output current is set so as to be very small. The impedance of the circuit comes to be very high.

[Embodiment of the Invention] An embodiment of the invention will be described with reference to the drawings based on an embodiment. FIG. 1 shows a circuit diagram of a voltage detector according to the present invention. I use two identical circuits to determine the polarity of the input voltage. When it is not necessary to indicate the polarity of the input voltage, only one circuit is required.
In the figure, the constant current circuits are FET4 and 5. (FET 9 and resistor 1
0) and the resistor 5. (Resistance 10) is for self-biasing.

In addition to probe 1. When a voltage is applied to the earth ring 2 so as to be negative, the base of the transistor TR6 is connected through a constant current circuit composed of the FET 4 and the resistor 5. A current is passed between the emitters to pass through the diode 8 and return to the earth ring 2. Thereby, the collector of TR6. The emitters are electrically connected to each other, and a current is supplied to the LED 7 (1 / 2.R) by the dry battery 12 to emit light. (LED 7 is anode. Common.
(1 / 2.R) and (1.
/ 2. G)).

Minus tip 1 When a positive voltage is applied to the earth ring 2, the base current of TR 11 flows through the FET 9 and the downhole 10, passes through the diode 3, and the probe 1
Then, TR11 is made conductive to cause the LED 7 (1 / 2.G) to emit light.

When an AC voltage is applied between the probe 1 and the earth ring 2, the above [0017] and [0018] are alternately repeated, and the LEDs 7 (1 / 2.R) (2 / 1.G) are alternately arranged. Emits light.

When there is no voltage between the probe 1 and the earth ring 2, the LED 7 (1 / 2.R) (1 / 2.G) does not emit light.

The presence or absence of an input voltage in the state of light emission of LED7 (1 / 2.R) (1 / 2.G). The type (AC, DC) and polarity can be known.

When there is no voltage between the probe 1 and the earth ring 2, TR6 and TR11 do not conduct. Since no current flows from the dry cell 12, no power switch is required.

FIG. 2 is an external view of the mounting. All circuits are incorporated in a cylindrical case 14 made of insulating material.
The probe 1 and the LED 7 (1 / 2.R) (1 /
2. G). An earth ring 2 and a self-check ring 13 made of a conductive material are attached to the intermediate portion. Of course 1,7,
2 and 13 are connected to an internal circuit.

FIG. 3 is an example of use of the voltage detector according to the present invention. The voltage detector of the present invention. Because the input impedance is very high. As shown in the figure, when the fingertip is held in the right hand, the fingertip touches the earth ring 2 and the human body resistance between the right and left fingertips is used as a substitute for ground return. (1 / 2.R) and (1 / 2.G) can be reliably emitted. Also

When there is a voltage between the power supply and the ground (commercial power supply, static electricity, radio wave, etc.), the earth ring is also used for power detection. The LED 7 (1 / 2.R) (1 / 2.G) can emit light as a leak current from the right fingertip through the human body to the ground.

By grasping the self-check ring 13 with the fingertip of the right hand and touching the fingertip of the left hand with the probe 1 or the earth ring 2, the voltage of the dry cell 12 is detected and the LED 7 (1 / 2.R) (1 /
2. G) can emit light to allow the self-checking of the detector body itself. In this state, a continuity test using a small current can be performed by inserting a circuit to be subjected to a continuity test between the probe 1 and the fingertip of the left hand.

At this time, the current flowing in the human body is ([002
[4] [0025] [Example of use of [0026]) There is no danger to the human body at all because it is a very weak current set by the constant current circuit inside the voltage detector.

[Effects of the Invention] The present invention provides: Because it is configured as described above. The following effects are obtained.

Since the input impedance of the probe 1 is high.
Has little effect on the circuit under test.

The voltage detection range is wide, and the voltage can be detected without switching from 1 volt to the static electricity range.

The frequency characteristics of the diode 3.8. Because it is determined only by the characteristics of The SHF. Can also be used with obi.

Whether probe input voltage is present. Type (AC, DC)
And DC polarity. Can be easily known by the blinking state of the two light emitting diodes.

Since a continuity test can be performed with a very small current, it can be used as a continuity sensor.

There is no need for a power switch so that no current flows except when there is a voltage between the probe 1 and the earth ring 2.

There is no need to worry about exhaustion of the battery due to forgetting to turn off the switch. Since the current consumption is small, the battery lasts longer.

Since no ground return is required, it can be conveniently used at any time if it is put in a pocket.

Since the number of parts is small and only small parts are used, it can be manufactured very small.

[0038]

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a voltage detector according to the present invention.

FIG. 2 is a mounting external view of a voltage detector according to the present invention.

FIG. 3 shows an example of use of a voltage detector according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Probe 2 Earth ring 3, 8 Died 4, 9 FET (Field effect transistor) 5, 10 Resistance 6, 11 TR (Transistor) 7 LED (1 / 2.R), LED (1 / 2.G) light emitting diode (Two-color emission type) 12 Dry battery 13 Self-check ring 14 Cylindrical case

Claims (1)

[Claims] An electric detector using a constant current circuit for a detection unit.