Portable bridge for measuring R and C on two transistors. Scheme, description

Free technical library

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

Portable bridge for measuring R and C on two transistors. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Measuring technology

Comments on the article

In the laboratory of each radio master, a device is needed to measure the resistance and capacitance of the capacitor. This is a bridge for measuring the capacitance of capacitors within 10 pF - 10 microfarads and the resistance value of resistors 10 Ohm - 10 mOhm. It is assembled according to the scheme shown in Fig. 1. It can be very small.

Portable bridge for measuring R and C on two transistors
Rice. 1. Schematic diagram of the bridge for measuring R and C

The range of measured resistance values of resistors is divided into six sub-ranges, and the measurement range of capacitor capacitances is divided into four sub-ranges. To switch subranges, switches P1 and P2 are used. The bridge is powered by an alternating audio frequency voltage obtained from a multivibrator assembled on transistors T1 and T2 (type P13 - P15). When adjusting the selection of resistors R10, R11 and R9, R12, they achieve the greatest amplitude of the generator oscillations. By changing the capacitance of capacitors C6 and C7, the generator is tuned so that the oscillation frequency is about 100 Hz. When measuring, a resistor or capacitor is connected to the Rx and Cx terminals. The measurement principle is based on balancing the bridge by changing the ratio of its arms. Thus, the measured element (R or C) is in the branch of the bridge formed by the bridge rheochord - potentiometer R7 and one of the resistors or capacitors of the subrange.

The sensitive element of the bridge is the high-resistance telephones Telf included in the diagonal of the bridge. The bridge is balanced by a wire potentiometer R7 for a minimum of audibility in phones. The device is powered by a battery for a flashlight (KBS-L-0,5) or a battery of small batteries.

The bridge circuit, multivibrator and battery are placed in a small metal or plastic (from a pocket receiver) case. Two terminals for connecting measured resistors and capacitors and three adjustable elements are installed on the top panel: potentiometer R7 and switches P1 and P2. If, when selecting parts, you have a switch for 11-12 positions, then both switches P1 and P2 can be replaced with one - a common one. Phone jacks for high-impedance telephones and a switch can be mounted either on the top or on the side of the case.

The following designations are applied on the scale of switch P1: in the position of switch P1 zero - "0", in position 1-Rx1 MΩ, in position 2-Rx100 kOhm, in position 3-Rx10 kOhm, etc. Similarly, with the addition of the symbol Cx are applied inscriptions and on the switch P2 scale.

The potentiometer scale is calibrated in relative numbers according to the reference resistances and capacitors, which are multiplied by the R or C subrange index. on one of the subranges. The resistance value R1 * is selected when checking the calibration of the device on a scale of 6-1 microfarads.

Author: Verkhalo Yu.N.

See other articles Section Measuring technology.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

The world's tallest astronomical observatory opened 04.05.2024

Exploring space and its mysteries is a task that attracts the attention of astronomers from all over the world. In the fresh air of the high mountains, far from city light pollution, the stars and planets reveal their secrets with greater clarity. A new page is opening in the history of astronomy with the opening of the world's highest astronomical observatory - the Atacama Observatory of the University of Tokyo. The Atacama Observatory, located at an altitude of 5640 meters above sea level, opens up new opportunities for astronomers in the study of space. This site has become the highest location for a ground-based telescope, providing researchers with a unique tool for studying infrared waves in the Universe. Although the high altitude location provides clearer skies and less interference from the atmosphere, building an observatory on a high mountain poses enormous difficulties and challenges. However, despite the difficulties, the new observatory opens up broad research prospects for astronomers. ... >>

Controlling objects using air currents 04.05.2024

The development of robotics continues to open up new prospects for us in the field of automation and control of various objects. Recently, Finnish scientists presented an innovative approach to controlling humanoid robots using air currents. This method promises to revolutionize the way objects are manipulated and open new horizons in the field of robotics. The idea of controlling objects using air currents is not new, but until recently, implementing such concepts remained a challenge. Finnish researchers have developed an innovative method that allows robots to manipulate objects using special air jets as "air fingers". The air flow control algorithm, developed by a team of specialists, is based on a thorough study of the movement of objects in the air flow. The air jet control system, carried out using special motors, allows you to direct objects without resorting to physical ... >>

Purebred dogs get sick no more often than purebred dogs 03.05.2024

Caring for the health of our pets is an important aspect of the life of every dog owner. However, there is a common assumption that purebred dogs are more susceptible to diseases compared to mixed dogs. New research led by researchers at the Texas School of Veterinary Medicine and Biomedical Sciences brings new perspective to this question. A study conducted by the Dog Aging Project (DAP) of more than 27 companion dogs found that purebred and mixed dogs were generally equally likely to experience various diseases. Although some breeds may be more susceptible to certain diseases, the overall diagnosis rate is virtually the same between both groups. The Dog Aging Project's chief veterinarian, Dr. Keith Creevy, notes that there are several well-known diseases that are more common in certain breeds of dogs, which supports the notion that purebred dogs are more susceptible to disease. ... >>

Random news from the Archive

ESP32-SOLO-1 WiFi module for low-end IoT devices 23.07.2019

The ESP32-SOLO-1 is Espressif's new high performance all-in-one module designed for a wide range of applications from low power wireless sensor networks to applications requiring voice processing or MP3 streaming audio encoding. The Wi-Fi+BT+BLE module is based on the ESP32-S0WD chip with one computing core.

Integration of Bluetooth, Bluetooth LE and Wi-Fi standards in a single chip guarantees the applicability of this module in any 2,4 GHz applications - both for direct data transfer to the user's device via Bluetooth, and for connection from anywhere in the world via a WiFi router. Support for BLE allows you to create inexpensive beacons (Beacon) based on the ESP32-SOLO-1 for positioning inside buildings or sending short information messages about goods.

Low current consumption - less than 5 μA - makes it possible to create stand-alone devices that can operate on batteries for years. The ESP32 supports speeds up to 150 Mbps and the 20 dBm output power guarantees good range.

ESP32-SOLO-1 uses freeRTOS operating system with LwIP and TLS 1.2 stack with hardware accelerator. Provides secure (encrypted) software download over the air (OTA).

Features of ESP32-SOLO-1:

Chip: ESP32-S0WD 5x5mm QFN
Integrated memory: 4 MB SPI FLASH
Frequency range: 2,4...2,5 GHz
WiFi support: 802.11 b/g/n (up to 150 Mbps)
Bluetooth support: v4.2 BR/EDR and BLE
Sensitivity: up to -97 dBm
Output power: 20 dBm (max, 11b mode)
Interfaces: UART, SPI, I2C, PWM, I2S, GPIO, ADC, DAC, etc.
Quartz resonator: 40MHz (10ppm)
Operating voltage: 2,7...3,6 V
Size: 18 x 25 x 3 mm; 38 pins (LCC)
Antenna: PCB with 2 dBi gain
Temperature range: -40...85°C.

Other interesting news:

▪ Iron Man Boots

▪ IR3720 monitor with power control technology

▪ Anti-radiation suit for the NASA lunar mission

▪ Inexpensive dense 3D memory

▪ Sunny instead of Wi-Fi

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ site section Electrician's tool. Article selection

▪ article Seven-segment and matrix indicators. Directory

▪ article Why does northeast India experience a rat infestation every 48 years? Detailed answer

▪ article Vendor who sells food for local consumption. Standard instruction on labor protection

▪ article Programmable code lock. Encyclopedia of radio electronics and electrical engineering

▪ article Scheme, pinout (pinout) cable Samsung A800 + pinout. 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