|
Arabic
Bengali
Chinese
English
French
German
Hebrew
Hindi
Italian
Japanese
Korean
Malay
Polish
Portuguese
Spanish
Turkish
Ukrainian
Vietnamese|
ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING Simple digital capacitance meter MASTER S. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Measuring technology In everyday work, radio amateurs often have to determine the data of radio elements. If it is not difficult to measure the resistance of a resistor - you can use an ordinary multimeter, then the situation is more complicated with capacitor capacities. It happens that the inscription on the body of the part is erased or the container is marked with an unknown code. Sometimes it is necessary to accurately select the capacitance (in time- and frequency-setting circuits, in filters, resonant circuits, etc.). In all these cases, a simple device will help you, a detailed description of which we begin to publish in this issue. PURPOSE AND TECHNICAL DATA The digital capacitance meter is designed to measure the capacitance of capacitors from units of picofarads to 9 microfarads and more, if we count the number of meter overflows. The presence of a constant bias voltage (not more than 999 V) at the input of the device allows you to measure the capacitance of both non-polar and polar oxide capacitors. The capacitance meter can quickly select or reject capacitors, which are one of the most unreliable components of radio equipment, which is usually found during its manufacture or repair. Oxide capacitors included in relatively high-resistance circuits can be tested with this device without tapping the leads. In addition, the capacitance meter can be used to measure the length of coaxial cables or the distance to a break. In this case, the capacitance of the cable is measured, and the resulting value is divided by the linear capacitance (one meter) of the cable, taken from the reference book or obtained empirically. For example, the linear capacitance of the RK-75 cable is about 67 pF, regardless of its diameter. The digital capacitance meter has a four-digit digital indicator and three measurement limits: 1 - 9999 pF; 1 - 9999 nF; 1 - 9999 uF. The measurement accuracy is 2,5% ± 20 digit of the selected range at an ambient temperature of 5°C. Temperature error in the range from +35 to +0,25°C does not exceed 1% per 0,08°C ("pF" limit], ±1% per 150°C ("nF" and "μF" limit). dimensions of the device - no more than 88x48xXNUMX mm. The appearance of the digital capacitance meter "Master C" is shown in fig. one.
The device does not contain scarce or expensive parts, it is easy to set up, which makes it easy to repeat even for beginners. If desired, you can increase the number of measurement limits by narrowing the range of each. This will slightly complicate the design of the device (you will need to install another switch), but will increase the measurement accuracy. OPERATING PRINCIPLE Let us turn to the functional diagram of the capacitance meter (Fig. 2). The main idea of its creation is borrowed from [1]. The measured capacitance Cx is connected to the measuring period pulse generator (GIP). The period of the generated pulses is proportional to Cx. They are continuously fed to the account control pulse shaper. According to the permission signal, which is generated every 0,8...1,0 with the cycle generator, the control pulse shaper generates a single pulse, the duration of which is equal to one pulse period at the GUI output.
On the leading edge of this pulse, the reset pulse shaper sets the counter - a digital indicator to the zero state. In addition, the control pulse arrives at the key and allows the passage of clock pulses to the input of the counter. These pulses are generated by a clock pulse generator (GTI). Their frequency at each measurement limit is chosen such that during the action of the control pulse, the counter receives a number of pulses equal to the numerical value of the measured capacitance in the appropriate units: picofarads at the "pF" limit, nanofarads at the "nF" limit, microfarads at the "μF" limit . Since the parasitic input capacitance of the device itself is always added to the measured capacitance at the GUI input, pulses are received at the counter input, the number of which is numerically equal to the sum of these capacitances. In this design, the input capacitance is 10...12 pF. In order for the counter to show a true value at the "pF" limit, the duration of the reset pulse is chosen such that the counter does not respond to a certain number of first pulses, the number of which corresponds to the parasitic input capacitance of the device. For greater clarity of the above in Fig. 3 shows timing diagrams explaining the operation of the main components of the capacitance meter, indicating the points on the circuit diagram where these pulses can be observed.
PRINCIPAL DIAGRAM The schematic diagram of a digital capacitance meter is shown in fig. 4. The GUI is a multivibrator based on a Schmitt trigger, consisting of an element DD1.3 and transistors VT1, VT2. It serves to convert the measured capacitance value into a time interval. Diodes VD1, VD2, resistor R9 and fuse FU1 protect the device from damage when connected to the input of a charged capacitor. Capacitor C7 and resistor R10 improve the linearity of readings when measuring small capacitances at the "pF" limit. The oscillation period of the multivibrator is determined by the capacitance connected to its input, and the resistance of one of the resistors in the feedback circuit - R14, R15 or R16, depending on the selected measurement limit. Transistors VT1 and VT2 are used to "enhance" the output of the Schmitt trigger, which improves its performance at the "uF" limit.
(click to enlarge) Capacitor C10 limits the pulse frequency at the output of the DD1.3 chip to the "uF" limit in those moments when the measured capacitor is not connected to the input. Without capacitor C10, the frequency of the multivibrator pulses at such moments increases to 4 ... 5 MHz, which can lead to improper operation of triggers DD2.1, DD2.2 and constant flashing of numbers on the indicators. Capacitor C9 performs similar functions at the "nF" limit, but its main task is to reduce the pickup level at the DD1.3 input from GTI pulses at the "pF" limit ("grounding" the jumper between the contacts of the switches SB1.2 - SB3.2). The GTI is assembled on the element DD1.1. The period of its oscillations at the limit of "pF" is determined by the capacitance of the capacitor C3 and the resistance of the resistors in the feedback circuit R1, R6. On the limits of "nF" and "uF" capacitors C3 or C1 are connected to capacitor C2 with chains of resistors with high resistance to increase the oscillation period. The clock frequency at the pF, nF, and µF limit is approximately 2 MHz, 125, and 1,5 kHz. The cycle generator is a multivibrator on the element DD1.2. It generates pulses that determine the time between measurement cycles or the holding time of readings. Triggers DD2.1 and DD2.2 form a control pulse shaper, which is used to generate a pulse whose duration is equal to the duration of one period of oscillation of the HIP, i.e., the charging and discharging time of the measured capacitor. This method of generating control pulses makes it possible to increase the accuracy when measuring the capacitance of capacitors with high leakage currents (an increase in the charge time is compensated by a decrease in the discharge time). The key on the element DD1.4 is used to issue counter DD3 - DD6 clock generator pulses for a time equal to the duration of the control pulse. The reset pulse shaper is assembled on a transistor VT3. From its collector circuit, a reset pulse enters the electronic meter before the start of each new measurement cycle. The duration of the reset pulse is set by the trimming resistor R11 and is chosen such that the electronic counter does not respond to the first 10-12 counting pulses at the "pF" limit. At other limits, the duration of this pulse is much shorter than the period of the clock pulses and does not affect the operation of the counter. The electronic counter contains four identical nodes A1 - A4. Each node consists of a decimal counter-decoder on a DD3 chip (DD4 - DD6) and a digital fluorescent indicator HG1 (HG2 - HG4). The indicator anodes are connected directly to the outputs of the K176IE4 chip. This simplifies the counter-indicator circuit, however, with such a switching circuit, the voltage at the anodes (luminous segments) of the indicator does not exceed the supply voltage of the microcircuit (usually 9 V). At such a voltage, the brightness of the glow of indicators (especially those that were in use) may turn out to be insufficient, in addition, the uneven glow of individual indicators is more pronounced. To increase and equalize the brightness of the glow of luminescent indicators, the supply voltage of the counter-decoder microcircuits is slightly overestimated (9,5 ... 9,7 V), which is quite acceptable. In addition, a small negative bias (2,5 ... 2,8 V) relative to the common wire is applied to the filaments (cathodes) of the indicators. In this case, the voltage on the anodes-segments of the indicators relative to the cathode changes from 2,5 ... 2,8 V (the segment is off) to 12,0 ... 12,5 V (the segment is on). This significantly increases the brightness of the glow of the segments and reduces the difference in the brightness of the glow of individual indicators [2]. The power supply unit of the device uses a unified transformer type T10-220-50, which was widely used in old calculators. At idle, it produces a voltage of about 40 V (pins 3 and 4) and 1,9 + 1,9 V (pins 5, 7 and 6, 7). To lower these voltages to the required ones, a reactive quenching element, capacitor C13, is included in the primary winding circuit. It lowers the voltage on the primary winding to about 100 ... 110 V. The secondary ones also decrease accordingly. The main disadvantage of this method of lowering the voltage is a strong increase in the output impedance of the power supply. Therefore, to reduce changes in the rectified voltage, depending on the load, zener diodes VD14, VD4 are connected in parallel with the smoothing capacitor C5. Together with the capacitor C13, they form a parametric stabilizer. You can use other transformers of suitable dimensions, including self-made ones, allowing you to obtain secondary voltages of 12 ... 18 V at a current of at least 30 mA and 0,75 ... 1,0 V at a current of 200 mA. When using such a transformer, capacitor C13 and zener diodes VD4 and VD5 must be excluded. The voltage drop across the HL1 LED and the VD6 diode creates a negative bias on the cathodes of the digital fluorescent displays. The voltage regulator is assembled on transistors VT4 and VT5. The features of his work are described in detail in [3]. The VD8 diode serves to reduce the supply voltage of the D1 and D2 microcircuits to the nominal (9,0 V) in order to somewhat reduce the current consumption when the microcircuits operate at high frequencies. CONSTRUCTION AND DETAILS The details of the device are placed on two printed circuit boards - upper and lower - made of foil fiberglass, fastened together by metal or plastic racks 14 mm high. The posts on the side of the transformer and for mounting the power switch are 29 and 20 mm long, respectively. All of them are with MZ internal thread. Their outer diameter is not more than 8 mm. On the top board, the location of the printed tracks of which is shown in Fig. 5, a, there are K176IE4 microcircuits, IV-3 digital indicators, two small-sized crocodile clips for connecting the measured capacitors, and input protection elements (Fig. 5, b). You can use IV-3A indicators, you just need to take into account that they have a different numbering of conclusions.
(click to enlarge) On the bottom board (Fig. 6) are the rest of the parts, including the elements of the power supply. Buttons P2K with dependent fixation are used as switches for measurement limits. Other types of switches will work, but then you need to make changes to the PCB. When using a small-sized ZP2N switch or a slide switch, similar to it in the switching scheme, the common point of contacts SB2.2 and SB3.2, connected to the normally closed contact SB1.2, is connected directly to terminal 13 DD1.3. With this limit switching scheme, capacitor C9 is excluded.
When making changes to the design of the device, it must be taken into account that at the "pF" limit, the pulses of the clock generator with a frequency of 2 MHz penetrate through the capacitances of the mounting to the input of the device and can reduce the accuracy of measuring small capacitances. Therefore, the conductors of the input circuits should be as short as possible and located away from the output circuits of the clock generator. Screening of input circuits is also useful. The screen is made in the form of a square of tinned sheet with dimensions of 25x25 mm, glued with electrical tape and rigidly soldered to the carrier bar of the P2K switch connected to a common wire so that it is above the DD1 chip and shields the input circuits located on the top board. The connection of terminal 13 of element DD1.3 with a switch is best done from a thin mounting wire laid above the screen. Fixed resistors are suitable type MLT-0,125 or MLT-0,25. Trimmer resistors R1, R3 and R5 are multi-turn, type SP5-2, SP5-3 or SPZ-39. Trimmer resistor R11 - small-sized, type SPZ-38a or SPZ-19a. Capacitor C3 - ceramic with negative TKE and marking M1500 or in extreme cases M750. Capacitors C1 and C2 must be thermally stable, C1 - P100, PZZ, MPO, MZZ - M150, C2 - K73-16, K73-17. Capacitor C7 is two turns with a pitch of 1 mm of the conductor - the output of the resistor R10, wound on an insulated wire connecting terminal 13 DD1.3 with the switch. It is better not to cut off the remaining tip of the output, as it can be useful in the final adjustment of the device. Capacitor C13 is made up of two MBM capacitors 0,25 uF at 500 V connected in series. A K73-16 or K73-17 capacitor for a voltage of at least 630 V is also suitable. When using more economical IV-ZA indicators, you can install one MBM capacitor 0,1 μF per 1000 V. With the correct choice of capacitance C13, the voltage at the rectifier output should not be less than 14 V when the input of the device is closed at the limit of "uF". Other types of capacitors recommended by [4] will also work. Keyboard power switch, type PT5-1. A sliding switch PD1 or a toggle switch MT1, mounted on a plate with holes for racks, is also suitable. The body of the device is made of plastic parts 2...4 mm thick according to fig. 7.
For the bottom of the case, it is better to take plastic with a thickness of at least 3 mm. This part is fastened with four screws MZ "sunk" to the block of printed circuit boards fastened with racks. So that the conclusions of the parts of the lower board do not rest against the lower part of the case, four plastic washers 2 mm high are glued on its inner side. The plate covering the cutout under the switch keys is glued to the bottom of the case last, after the case is completely assembled and the top cover of the case is fixed. Glued with the side walls, it is put on in front and fixed on the left by the lower part of the "crocodiles", while the right side is fixed with two screws to the uprights. To open the crocodile clips, buttons cut from push-button switches KM1 - 1 or KM2 - 1 were used. Buttons can be made from two rivets with a diameter of 4 ... 5 mm. They are mounted on top in guide bushings 7...9 mm high with M8 external thread and slightly flared so that they do not fall out. The bushings are fixed on the top cover with nuts. The indicator window on the top of the case is covered with green organic glass to reduce glare from the indicator glass bulbs. The necessary inscriptions near the controls can be written on good paper, or better printed on a printer and glued to the body with Moment or PVA glue. To prevent the inscriptions from being erased and not contaminated, the paper should be pre-laminated on the front side or covered with a thin layer of transparent varnish. INSTALLATION After etching and washing the printed circuit boards from the remnants of protective varnish or paint, the printed tracks must be lightly cleaned with fine sandpaper, wiped with a napkin soaked in alcohol, and alcohol-rosin varnish (flux) applied. When the varnish is dry, you can proceed with the installation. It is better to start with the power supply transformer, then install all the parts of the rectifier and stabilizer. The cases of capacitors C13 and resistor R17 are completely insulated with the help of "cambric" and electrical tape, mounted in a single assembly and fixed on the board with jumpers J14 and J15. The ends of the power cord, the elongated ends from the capacitor C13 and the transformer are soldered to the conclusions of the switch, after which the switch SA1 is fixed on the board. To the conclusions of SA1, in the break of the power cord, you can solder a small fuse of 0,1 A. All racks surrounding the capacitor C13 must be plastic, metal racks must be insulated. All bare areas of the terminals of the capacitor C13 and resistor R17 should preferably be filled with hot melt adhesive or other insulating compound. Such a thorough isolation of network circuits and the absence of printed conductors connected to the network will allow in the future to carry out quite safely measurements, adjustment and adjustment of the capacitance meter. After completing the installation of the power supply, you need to check it. To do this, a load equivalent is temporarily connected to the +9,6 V stabilizer output - an MLT-1 resistor with a resistance of 470 ... 510 Ohms - and the output voltage is checked. If necessary, the output voltage of the stabilizer can be adjusted by selecting the Zener diode VD7. This preliminary check of the stabilizer reduces the likelihood of damage to the device when you first turn it on. Having finished checking the power supply, the power cord is temporarily unsoldered so that it does not interfere, and the rest of the parts are mounted, paying special attention to the jumpers. There are 37 of them in total, including flexible jumpers between the top and bottom boards. Jumpers J1, J9, J10, J24 - J30 are mounted before the radio elements are installed. Jumpers J11 - J23 secure the corresponding parts and are installed during installation. Jumpers J2 - J5 are installed after mounting the switches SB1 ... SB3 and the DD1 chip. Lastly, having completed the installation of all elements on both boards, flexible connecting jumpers between the boards about 25 mm long are soldered on the top board. The boards are fastened together with racks, the free ends of the jumpers are soldered to the bottom board. At the time of setting up the device, the jumper R9 - VD1 can be made longer so that it is convenient to open the boards. But before the final adjustment, it must be shortened to a minimum. The rear ends of the crocodile clips, and especially the pins of the switches SB1 - SB3, must be carefully tinned before being installed on the board. Elements C9 and R14 are installed after mounting the switches SB1 - SB3 and shortening the upper terminals to 1,5 mm. Mounted components should not rise above the board by more than 12 mm. After completing the installation, the lower terminals of all parts on the boards are shortened to 1,5 mm (they can be slightly trimmed with a file with fine notches). Places of rations should be treated with a brush moistened with alcohol to remove dirt, and then again apply pure alcohol-rosin varnish. CHECK AND ADJUSTMENT After checking the installation of the device for compliance with the circuit diagram, you need to make sure that short circuits are excluded in the power circuits. Now you can turn on the power and check the voltage at C14, the output voltages of the stabilizer +9,6 V and +9,0 V, as well as the glow voltage (0,75 ... 0,8 V). If everything is normal and the indicators are lit, you should make sure that the individual components of the capacitance meter are working correctly. The GTI output (pin 10 DD1.1) should have rectangular pulses with a frequency of 1,8 ... 2,0 MHz with the "pF" button pressed, 120 ... 130 kHz - "nF", 1,4 ... 1,6 kHz - "uF". This can be verified using an oscilloscope with a calibrated sweep or a frequency counter. Then, a capacitor with a capacity of 82 ... 100 pF is connected to the input of the device, the "pF" button is pressed and the operation of the GUI multivibrator on the DD1.3 element and transistors VT1, VT2 is checked. At the output of the multivibrator (pin 11 DD1.3) there should be rectangular pulses with a period of about 100 times the period of the clock pulses. Similarly, the operation of this multivibrator is checked within the limits of "nF" and "μF". To do this, capacitors with a capacitance of 100 nF and 100 μF are connected to the input of the device. After that, they are convinced of the operation of the generator of measurement cycles assembled on the element DD1.2. The output of this generator should have pulses with a period of 0,8 ... 1,0 s. With the same frequency (within the limits of "pF" and "nF" when the corresponding capacitances are connected), the node on the elements DD2.1 and DD2.2 generates a control pulse, which can be checked at input 6 of the DD1.4 element using an oscilloscope or a logic probe. At pin 4 of the element DD1.4, a burst of pulses should appear at the time of the control pulse. At the "µF" limit, the period of control pulses can reach several tens of seconds. In the same way, with an oscilloscope in standby mode, or better with a logic probe, you can check the generation of a reset pulse at the collector of the VT3 transistor. To check the operation of the counter with indicators, it is convenient to use a logical pulsator [5]. External signs of the correct operation of the capacitance meter are as follows: if the capacitor is not connected to the input, stable zero readings are displayed at the limit of "nF" and "μF"; at the "pF" limit, with a light touch of the input terminals by hand, readings of several tens of picofarads are displayed. INSTRUMENT SETUP To set up the device, you will need a set of capacitors with an accuracy of at least 0,5 ... 1,0% or another capacitance meter with no less accuracy. First, the reset pulse width is adjusted to obtain zero readings of the device at the "pF" limit with free input terminals (capacitance compensation of the input circuits). To do this, rotate the tuned resistor R11 to one of the extreme positions until several picofarads are indicated. Then slowly rotate in the opposite direction until zero readings appear. Then a capacitor with a capacity of about 2000 pF is connected to the input of the device and the correct readings are set using the trimmer resistor R1. Next, you need to check the correctness of measuring small capacitances (1 ... 3 pF) and, if necessary, adjust the zero readings again. Then, the linearity of the readings of the device is checked when capacitors with a capacity of 10 to 100 pF are connected to it. Usually, when there is no C7R10 chain, the readings of the device when measuring such capacities are overestimated by 1 ... 2 pF. The inclusion of the chain allows you to partially eliminate the non-linearity of the instrument readings in the specified range. If the readings are too high, you should increase the capacitance of the capacitor C7 by winding the turns of the wire-output R10 on the jumper from the output 13 DD1.3 to the switch SB1.2 with tweezers. If the readings are too low, then you need to rewind the wire a little. In general, the ratings of the C7R10 chain depend on the frequency of the clock pulses at the "pF" limit. With an increase in the GTI frequency to 2,5 ... 2,8 MHz, a chain with ratings R10 - 2 MΩ, C7 - 1,5 pF may turn out to be optimal. At other limits, the non-linearity of the readings is negligible and no correction is required. Setting the "nF" and "uF" limits comes down to connecting capacitors with a capacity of about 2000 nF (2 uF) and 2000 uF and correspondingly adjusting the meter readings using trimming resistors R3 and R5. During the operation of the device, there is no need to adjust the resistors R1, R3 and R5, so you can not make holes in the case to adjust them. When using home-made metal buttons (without return springs) to open the "crocodiles" after putting on the top cover, it is necessary to correct the zero readings of the counter, so a hole for adjusting the resistor R11 is provided. MODERNIZATION To power the device, you can use two elements 316 with a voltage converter according to the circuit in fig. 8.
This voltage converter with pulse-width stabilization [6], when properly manufactured and configured, works well in the supply voltage range from 2,0 to 3,2 V, maintaining a voltage of +9,6 V (18 mA) and a pulse voltage for heating at the output. (effective value 0,75 ... 0,8 V, current 160 ... 180 mA) with sufficient accuracy. However, when it is repeated, tuning problems may arise due to the complexity of manufacturing a pulse transformer with precisely specified parameters and selecting transistors. To increase the range of supply voltages and reduce the criticality of the setting, it is better to use an additional stabilizer (VT3, VT4 - in Fig. 8). In this case, the voltage at the output of the converter must be increased to +11,5 ... 12 V. The output voltage depends on the stabilization voltage of the zener diode VD1. The supply voltage of the converter simultaneously serves to create a negative bias in the heating circuits. The circuit diagram of the converter differs from the circuit of the prototype [6] mainly only in the ratings and types of elements. Transistor VT1 KT203B with a current transfer ratio of 30 to 60 can be replaced by KT361 with any letter index. Transistor VT2 with a current transfer ratio of 25 ... 80 is better to take the KT630A series, but you can also use KT815, KT608 with any letter indices. Transformer T1 is wound on a ferrite ring K16x10x4,5 M1000NM. The sharp edges of the ring are slightly dulled with an emery bar, then a narrow insulating tape or film is wound in two layers. The windings are evenly spaced around the circumference of the ring. Winding W1 contains 55 turns of PELSHO 0,22 ... 0,27 wire, W2 - 19 turns of PELSHO 0,1 ... 0,22, W3 - 6 turns of PEL or PELSHO 0,27 ... 0,41. You can use ferrite cores with a higher magnetic permeability or with other sizes, including W-shaped ones, but then you will need to recalculate the number of turns. When assembling, it is necessary to pay attention to the correct connection of the terminals of the windings W1 and W2. If, when the power is turned on, the output voltage is absent or below 11,5 V, you need to select the mode with a trimming resistor R2. If this does not help, you should short-circuit resistor R3 (it serves to eliminate self-excitation at high frequencies when using some types of transistors) and again try to select the mode with resistor R2. The converter can be considered configured if, when the supply voltage changes from 3,2 to 2,0 V, with a rated load (750 and 5 ohms at the outputs + 12 and 0,75 V, respectively), the voltage at the +12 V output does not fall below 10,5 .2 V, otherwise you need to choose a different type of transistor VT3,2 or the number of turns of the pulse transformer. The supply current of the converter with a decrease in the supply voltage from 2,0 to 120 V increases, being in the range of 155 ... 30 mA, the pulse repetition period varies within 60 ... XNUMX μs. The node on the transistor VT5 serves to control the discharge of the battery. When the voltage at the output of the stabilizer decreases by 70 ... 100 mV relative to the nominal, VT5 opens and decimal segments light up on all digital indicators. With such a decrease in the supply voltage, the additional error does not exceed 1%. The threshold for the battery discharge indicator is set by resistor R7. The dimensions of the converter together with the battery compartment do not exceed the dimensions of the mains power supply, it is only necessary to provide an easily removable cover for access to the compartment with 316 elements. Perhaps the most significant drawback of this device is the increased temperature error at the "pF" limit, reaching up to 0,25% per 1°C. At other limits, it is easily compensated by the selection of capacitors C1 and C2 with the appropriate TKE. At the "pF" limit, the GTI frequency (about 2 MHz) is close to the limit, it is necessary to use a timing circuit with a small RC value. In this case, according to the author, the influence of the instability of the input capacitance and the temperature dependence of the output resistance of the CMOS transistors of the DD1.1 element of the K561TL1 microcircuit amplifies. To reduce this effect, you can try using a parallel or series chain of a conventional resistor and a negative TCR thermistor as resistor R6. The resistance ratio of these resistors depends on the specific TCR value. To improve the accuracy of measuring some capacitances, it is tempting to use an additional counter-divider by 10, setting it at the output of the GUI with a decimal point before the least significant digit. In this case, it must be taken into account that significant impulse noise from the GTI at the input of the device at the "pF" limit, due to the synchronization phenomenon, will not give the desired result without the use of special measures. The level of these noises can be easily measured by connecting an oscilloscope with a 1/10 divider having an input impedance of at least 10 MΩ to the input of the device. Literature
Author: V.Andreev
Machine for thinning flowers in gardens
02.05.2024 Advanced Infrared Microscope
02.05.2024 Air trap for insects
01.05.2024
▪ LMP8100 Programmable Gain Amplifier ▪ World's first optical isolator developed ▪ SSD data transfer speed doubled
▪ section of the site Mobile communications. Article selection ▪ article He who does not remember his past is doomed to relive it again. Popular expression ▪ article What accident actually brought about Linux? Detailed answer ▪ article Washing and cleaning of machines and equipment. Standard instruction on labor protection ▪ article Magic wand and gifts. Focus Secret
Comments on the article: a guest Great stuff, thanks! [up]
Home page | Library | Articles | Website map | Site Reviews
www.diagram.com.ua |
See other articles Section 
Latest news of science and technology, new electronics:
All languages of this page