Sound and light probe. Scheme, description

Free technical library

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Schemes of radio-electronic and electrical devices

Sound and light probe. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Measuring technology

Comments on the article

I have been using this compact simple device for the fifth year and it has never let me down. The probe is convenient, placed in the breast pocket of overalls, always at hand.

Despite the extreme simplicity of the circuit, this is a universal device. They can control AC (0,1 mV to 400 V) and DC (0,5 V to 24 V) voltage. The probe warns of the presence of a dangerous voltage in the range from 80 to 400 V. It can be used to determine the value of resistance, capacitor capacitance, and frequency parameters. The probe is powered by four D-0,1 batteries. Its mass is 120 g.

The operating modes of the probe are as follows.

1. SA1 and SA2 are off (as shown in the diagram). SA3 - too (the button is not pressed). The multivibrator circuit is not powered, and only high voltage can be controlled by the probe. At a voltage of more than 80 V, the neon lamp EL1 will light up.

2. The SA3 button is pressed. Positive potential comes from GB1 to XP2. If you connect the probes XP1 and XP2, then power will be supplied to the circuit. The resistance R1 is included in the base circuit of the transistor VT2. The sound of the natural frequency fo will be heard and the EL1 lamp will light up in full heat. The current through the probes is approximately 80 mA (this is how much the light bulb consumes). As Rx increases, the current decreases, the bulb burns weaker, the sound changes. There comes a moment when the sound disappears (about 20 ohms), then the light bulb stops burning (about 30 ohms), then the LED stops glowing (about 50 ohms). This mode allows you to determine low resistances, starting from 0,5 ohms.

3. SA2 is on (contacts 1-2 are closed). This is the main mode "On without backlight".

If Rx=0, then the sound will be the same whether the button is pressed or not, because the circuit is powered by the same voltage, the same resistance R1 = 2 kOhm is included in the base circuit of the transistor VT24. In this case, the current comes from XP1 and XP2 and is equal to 50 μA if the button is not pressed. If the button is pressed, current flows from XP2 to XP1 and is 5 mA. This property is used when testing capacitors, electronic switches, semiconductor devices.

If Rx>0, then when the button is not pressed, R1 + Rx is introduced into the VT2 base circuit, which reduces the frequency. When the button is pressed, the positive potential from the power source is supplied to the VT1 base through R2, and to the power supply of the multivibrator circuit through Rx. This increases the frequency. The probe will "sing" when we press and release the button, indicating that Rx is within 20 ohms - 1 k ohms. If Rx > 1 kOhm, then there is no sound when the button is pressed.

4. SA1 enabled. The "On with backlight" mode does not fundamentally differ from the previous mode. The thresholds of the multivibrator operation and the levels of current signals will change, because A light bulb consumes a significant amount of energy. In this mode, you cannot test low-power semiconductor devices.

The circuit board is made of one-sided foil fiberglass. The figure shows the main dimensions.

When using a probe, you need to remember two simple conditions:

The button must not be pressed while monitoring the 24V voltage.

It is impossible to check semiconductor devices in mode 2 and 4 when a light bulb is connected and a significant current flows through the probes.

See other articles Section Measuring technology.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Machine for thinning flowers in gardens 02.05.2024

In modern agriculture, technological progress is developing aimed at increasing the efficiency of plant care processes. The innovative Florix flower thinning machine was presented in Italy, designed to optimize the harvesting stage. This tool is equipped with mobile arms, allowing it to be easily adapted to the needs of the garden. The operator can adjust the speed of the thin wires by controlling them from the tractor cab using a joystick. This approach significantly increases the efficiency of the flower thinning process, providing the possibility of individual adjustment to the specific conditions of the garden, as well as the variety and type of fruit grown in it. After testing the Florix machine for two years on various types of fruit, the results were very encouraging. Farmers such as Filiberto Montanari, who has used a Florix machine for several years, have reported a significant reduction in the time and labor required to thin flowers. ... >>

Advanced Infrared Microscope 02.05.2024

Microscopes play an important role in scientific research, allowing scientists to delve into structures and processes invisible to the eye. However, various microscopy methods have their limitations, and among them was the limitation of resolution when using the infrared range. But the latest achievements of Japanese researchers from the University of Tokyo open up new prospects for studying the microworld. Scientists from the University of Tokyo have unveiled a new microscope that will revolutionize the capabilities of infrared microscopy. This advanced instrument allows you to see the internal structures of living bacteria with amazing clarity on the nanometer scale. Typically, mid-infrared microscopes are limited by low resolution, but the latest development from Japanese researchers overcomes these limitations. According to scientists, the developed microscope allows creating images with a resolution of up to 120 nanometers, which is 30 times higher than the resolution of traditional microscopes. ... >>

Air trap for insects 01.05.2024

Agriculture is one of the key sectors of the economy, and pest control is an integral part of this process. A team of scientists from the Indian Council of Agricultural Research-Central Potato Research Institute (ICAR-CPRI), Shimla, has come up with an innovative solution to this problem - a wind-powered insect air trap. This device addresses the shortcomings of traditional pest control methods by providing real-time insect population data. The trap is powered entirely by wind energy, making it an environmentally friendly solution that requires no power. Its unique design allows monitoring of both harmful and beneficial insects, providing a complete overview of the population in any agricultural area. “By assessing target pests at the right time, we can take necessary measures to control both pests and diseases,” says Kapil ... >>

Random news from the Archive

A new way to make chocolate 01.09.2021

Canadian scientists have made a discovery that makes the texture of chocolate better, and the process of making it easier and safer for the environment.

The texture of chocolate and its familiar appearance is the result of tempering - a complex process of repeated heating and cooling of the chocolate mass. This is how its glossiness is acquired, the characteristic crunch when broken and melting at a certain temperature. In the physical processes inside the chocolate, the cocoa butter fatty acid crystals take on a structured shape.

The addition of just one ingredient at a concentration of about 0,1% simplifies the process of tempering chocolate. The phospholipid helps the fatty acid crystals to take shape faster and only one heat is required.

In large factories, tempering is done by complex machines that leave a carbon footprint. Their need will disappear in connection with the new discovery.

Other interesting news:

▪ AUP ESD Logic Series

▪ Video surveillance in Moscow schools

▪ The car will understand that the driver is talking on a mobile phone

▪ More than 10 thousand scientific articles retracted

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ site section Color and music installations. Selection of articles

▪ article No great Patroclus! The scornful Thersites lives! Popular expression

▪ article Are people able to feel the gaze directed at them? Detailed answer

▪ article A dyer at work on dye barges. Standard instruction on labor protection

▪ article Balcony wind turbine. Encyclopedia of radio electronics and electrical engineering

▪ article Pinout for different models of mobile phones. Part 1. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages of this page

Home page | Library | Articles | Website map | Site Reviews