DIY ESR meter. There is a wide list of equipment breakdowns, the cause of which is precisely electrolytic. The main factor in the malfunction of electrolytic capacitors is “drying out,” familiar to all radio amateurs, which occurs due to poor sealing of the housing. In this case, its capacitive or, in other words, reactance increases as a result of a decrease in its nominal capacity.
In addition, during operation, electrochemical reactions take place in it, which corrode the connection points between the leads and the plates. The contact deteriorates, eventually forming “contact resistance”, sometimes reaching several tens of ohms. This is exactly the same if a resistor is connected in series to a working capacitor, and moreover, this resistor is placed inside it. This resistance is also called “equivalent series resistance” or ESR.
The existence of series resistance negatively affects the operation of electronic devices by distorting the operation of capacitors in the circuit. Increased ESR (about 3...5 Ohms) has an extremely strong impact on performance, leading to the burning of expensive microcircuits and transistors.
The table below shows the average ESR values (in milliohms) for new capacitors of various capacities depending on the voltage for which they are designed.
It is no secret that reactance decreases with increasing frequency. For example, at a frequency of 100 kHz and a capacitance of 10 μF, the capacitive component will be no more than 0.2 Ohm. When measuring the drop in alternating voltage having a frequency of 100 kHz and higher, we can assume that with an error in the region of 10...20%, the result of the measurement will be the active resistance of the capacitor. Therefore, it is not at all difficult to assemble.
The pulse generator with a frequency of 120 kHz is assembled using logic elements DD1.1 and DD1.2. The generator frequency is determined by the RC circuit on elements R1 and C1.
For coordination, element DD1.3 was introduced. To increase the power of pulses from the generator, elements DD1.4...DD1.6 were introduced into the circuit. Next, the signal passes through the voltage divider across resistors R2 and R3 and goes to the capacitor Cx under study. The alternating voltage measurement unit contains diodes VD1 and VD2 and a multimeter as a voltage meter, for example, M838. The multimeter must be switched to DC voltage measurement mode. The ESR meter is adjusted by changing the R2 value.
The DD1 - K561LN2 microcircuit can be replaced with K1561LN2. Diodes VD1 and VD2 are germanium, it is possible to use D9, GD507, D18.
The radio components of the ESR meter are located on, which you can make yourself. Structurally, the device is made in the same housing with the battery. Probe X1 is made in the form of an awl and attached to the body of the device, probe X2 is a wire no more than 10 cm in length with a needle at the end. Capacitors can be checked directly on the board; there is no need to unsolder them, which makes it much easier to find a faulty capacitor during repairs.
1, 5, 10, 15, 25, 30, 40, 60, 70 and 80 ohms.
It is necessary to connect a 1 Ohm resistor to the probes X1 and X2 and rotate R2 until the multimeter reads 1 mV. Then, instead of 1 Ohm, connect the next resistor (5 Ohms) and, without changing R2, record the multimeter reading. Do the same with the remaining resistances. The result is a table of values from which the reactance can be determined.
The article provides circuit options for a simple device that allows you to find faulty electrolytic capacitors without removing them from the circuit. In addition, this device can “ring” electrical circuits, check the passage of signals in HF and LF devices, and evaluate winding products for the presence of short-circuited turns.
Several years ago, on the Internet, the author discovered a diagram of a simple device that allows you to identify faulty electrolytic capacitors. Having become interested in this, the author decided to assemble and test this “ESR meter”. The result exceeded all expectations: the Toshiba TV, which was under repair for several days (the power supply did not start), was repaired in literally 5 minutes. Using this device, two electrolytic capacitors with increased ESR were detected, which had previously been soldered from the board and tested with a conventional tester for “arrow twitching”. The needle deviated, and the serviceability of the capacitors was beyond doubt. After replacing the capacitors the TV worked fine.
So, first things first. First, let me give you a little theory to better understand the essence of the problem. ESR is an abbreviation for the English words Equivalent Serial Resistance, which means “equivalent series resistance”. In a simplified form, an electrolytic (oxide) capacitor consists of two aluminum strip plates, separated by a gasket made of porous material impregnated with a special composition - electrolyte. The dielectric in such capacitors is a very thin oxide film that forms on the surface of aluminum foil when a voltage of a certain polarity is applied to the plates. Wire leads are attached to these tape covers. The tapes are rolled into a roll, and the whole thing is placed in a sealed housing. Due to the very small thickness of the dielectric and the large area of the plates, oxide capacitors have a large capacity despite their small dimensions.
Circuit diagram of a simple ESR meter 
Rice. 5 Appearance of the device
Rice. 6 Location of parts inside the housing
Rice. 7 RC generator
Device R/L/C/ESR-Meter for measuring low resistance , inductances , capacitor capacities and equivalent series resistance (ESR) or in English Equivalent Series Resistance (ESR) electrolytic capacitors
Due to the fact that switching power supplies, inverters and other converters operating at high frequencies are now very widely used, when repairing them there was a need for a device for measuring the ESR of electrolytic capacitors. For several months I “walked” through the Internet in search of the device I needed, collected several analog and digital devices for measuring ESR and settled on one, which I propose to repeat. Many devices offered on the Internet, including a semiconductor device tester, the description of which is given, in addition to their main functions, they can measure capacitance, inductance, etc. But, unfortunately, I have not found a universal measuring device that can measure absolutely everything and qualitatively. I looked through a bunch of diagrams and videos onYouTube and I decided for myself that I needed to have several different devices that could do their job. In any case, all of our homemade products are not high-precision measuring instruments, but they provide measurements with sufficient accuracy for our creativity. Additionally, I personally am pleased that the device was assembled with my own hands, and it even works :) in short, for those who are interested, read on about the designer that I offer to everyone...
With the help of the designer, you can assemble a very useful and, most importantly, easy-to-assemble and set up device, which will be very useful in everyday work for a radio equipment repair specialist, radio amateur, etc. - meter for inductance, capacitance and equivalent series resistance (ESR or ESR) of electrolytic capacitors, very small resistances (milliohmmeter) -« LCMTESTER» . The display is performed on a 2x16-character liquid crystal display with backlight function.
Specifications:
What is EPS or ESR? Why do you need to measure it?
ESR (Equivalent Series Resistance) - equivalent series resistance, is the sum of the series-connected ohmic resistances of the contacts of the leads and the electrolyte with the plates (plates) of the electrolytic capacitor, which is the most important parameter of electrolytic capacitors. In the Russian abbreviation - Equivalent Series Resistance - EPS. Essentially, an ESR meter is an AC ohmmeter operating at a frequency of 50...120 kHz. At these frequencies, the capacitance of electrolytic capacitors is low (about zero), so the readings of this ohmmeter when checking capacitors give ESR. The lower this resistance, the better the electrolytic capacitor! Losses in the dielectric, caused by the peculiarities of its polarization, constitute the main part of the losses in the capacitor and are determined by the material, as well as the thickness of the dielectric layer. There is no need to consider in detail the processes of all types of polarization, but it can be briefly explained as follows. Dielectric particles with a charge, under the influence of an alternating electric field, are forced to perform involuntary mechanical vibrations due to their reorientation and displacement (polarization). In the dielectric layers close to the plates, charges, without leaving their bonds, actively participate in the general process of recharging the capacitor. In essence, the thickness of the actual dielectric is reduced. As a result, the capacitance of the capacitor increases significantly, but, due to the inertia and internal friction of the associated particles, the processes are accompanied by the release of heat and energy losses in the conductive layers of the dielectric. With increasing frequency, dielectric losses increase proportionally. As a result, the phase angle between current and voltage will not be 90°, as in an ideal capacitor, but somewhat less. The tangent of the angle δ making this difference from 90° is called the dielectric loss tangent. A similar shift occurs in the circuit when a capacitor and resistor are connected in series. In this regard, for calculations, the concept of series equivalent resistance ESR is adopted, in which dielectric losses are summed up with the active resistance of the plates, connections and terminals, representing, in fact, a resistor connected in series with a capacitor. In electrolytic capacitors, a significant part of the ESR is the resistance of the liquid electrolyte, which is used as a component of one of the plates to ensure maximum contact area with the dielectric. If the resistance of the electrolyte in a capacitor is considered as a conductor with a cross-section equal to the area of one of the plates and a conductor length approximately equal to the thickness of the impregnated paper, we can assume that this value will be relatively small. In real medium-sized capacitors, a typical value will be 0.01 ohms at 20°C. But, it should be taken into account that for high-capacity capacitors used in filters of rectifiers of switching power supplies at an operating frequency of about 100 kHz, when its reactance is measured in thousandths of an Ohm, this value will amount to quite large losses. The magnitude of dielectric losses at such frequencies in electrolytic capacitors of switching power supply filters is usually several times greater, and only in the best cases can it be approximately equal to or even less than losses in the electrolyte. The resistance of the electrolyte depends significantly on temperature due to changes in the degree of its viscosity and ion mobility. During operation, the dielectric and electrolyte are heated by alternating current, and therefore the resistance of the electrolyte can significantly decrease, then the ESR of the capacitor will be determined mainly by its dielectric losses. In cases of heating to boiling temperature, the electrolyte loses its original properties and upon subsequent cooling it becomes more viscous, which significantly increases its resistance. Further operation will cause even greater heating and deterioration in the quality of the electrolyte, which will subsequently lead to the unsuitability of the capacitor for further operation in the device. Typically, faulty electrolytic capacitors in which the electrolyte has boiled are identified visually by a swollen and depressurized housing. For the reliable operation of electrolytic capacitors, the correct choice of its type, rating and maximum voltage depending on the modes is very important. For converter filters operating at frequencies of tens of kilohertz, manufacturers produce special capacitors with low ESR and indicate the total alternating current resistance (impedance Z) for all ratings in the tables. The type of such capacitors is accompanied by a mark in the technical documentation - Low impedance or Low ESR. An increase in the ESR of a capacitor by several Ohms, and sometimes by several tenths of an Ohm, may cause the device in which it is installed to malfunction, which is sometimes impossible to detect with existing capacitance meters that are not able to take into account other parameters of the capacitor! Typically, in repair practice, special accuracy in measuring ESR is not required, so a noticeable error in probes often does not cause inconvenience in finding faulty elements, and determining the condition of a capacitor with a probe can be simplified to assessing its quality based on the principle of whether it is suitable or not suitable for work in a specific unit of the device. But it should be noted that for capacitors operating at high pulse currents, for example, in converter filters, a more objective assessment of quality is required, and an error of tenths and even hundredths of an Ohm can be significant.
This information was borrowed from the website http://tel-spb.ru, there more detailed theoretical information on ESR measurement issues is posted
Unlike universal meters offered on the market, and meters specializing specifically in measuring ESR, this device has high accuracy and displays reliable data of measured values on the display, and not just anything, just to bear the proud name of an ESR meter - this has been tested repeatedly on practice.
Assembly and calibration of the device:
The kit includes: a printed circuit board with a mask and markings of radio components, all radio components necessary for assembling the tester, buttons with caps, a wire with a connector for a crown battery, a socket for connecting an external power supply, a 2x16 LCD display. It is necessary to solder all the parts into the board according to the circuit diagram, wash off the flux and inspect the printed circuit board to ensure there are no unnecessary solder jumpers between the tracks. After this, you can connect the display and power supply. Once assembled without errors, the device starts working immediately. It is only necessary to adjust the contrast of the LCD display the first time you turn it on using the trimming resistor RV1. To do this, you need to supply power to the tester - press the “POWER” button and adjust the display contrast. After turning on the device, it is necessary to calibrate it.
Initial calibration in mode “C” occurs when the device is turned on (the device must be in this mode when the device is turned on).
If the zero is “gone”, then for calibration you need:
1. Turn on the calibration button.
2. Wait for a message like R=0238 Ohm to appear
3. Turn off the button by pressing again and remove your hands from the device.
4. Wait for the confirmation message about type C->0 calibration. The resistance reading should reset to zero. If the zero has “gone”, then you can repeat the calibration. But it is imperative to allow the processor to remember the state and not interrupt the process.
For mode “L” everything is exactly the same, you just need to close the contacts of the inductance measurement connector with a jumper (for mode “C” the contacts are open).
Similarly, for ESR mode you need Necessarily do a calibration, otherwise small values of R may be “eaten up”:
1. Connect the contacts of the capacitance measurement connector and ESR with a jumper.
2. Press the calibration button and information about the voltage applied to the capacitor and the ESR measurement frequency will be displayed.
3. After this, wait for the message R= 0238 Ohm to appear and press the button. The resistance reading should reset to zero. If the zero has “gone”, then you can repeat the calibration. But it is imperative to allow the processor to remember the state and not interrupt the process.
The current consumed by the device is very small, about 8-10 mA, so the 6F22 Krona 9V batteries will last for a very long time. However, the display backlight does not work. For the display backlight to work, you need to connect an external 7-12V network adapter to the connector on the board.
ESR Diagram of Electrolytic Capacitors:
From the above graphs, you can determine the maximum allowable resistance (ESR value) of an electrolytic capacitor depending on the capacitance and operating voltage. Therefore, to determine the highest equivalent resistance of the electrolyte, it is necessary to find the value (mark a point) of the capacitance indicated on the capacitor body on the vertical axis and draw a horizontal straight line through this value until it intersects with the required graph. The schedule must be selected based on the rated operating voltage of the capacitor. From the point of intersection of the horizontal line and the graph, we lower the perpendicular to the horizontal axis. Using the scale on the horizontal axis, we determine the highest permissible ESR value for the capacitor under test. In addition, the device displays the dielectric loss tangent of the dielectric. Display is performed using the Bar Graph indicator (colored bar). The more the indicator is colored, the worse the condition of the dielectric and vice versa.
What does the inscription m60, etc. mean? Capacitor memory effect. The capacitor is charged with a constant voltage, then left alone for a while, after which the voltage on the capacitor is checked. The smaller the "m**" the better, for m60 memory, I think it's something similar to a bad capacitor from some power supply, but a good electrolytic capacitor has "m20" or less, at least most of them are I measured it and it was the same size. And the best ones may have "m1-m2", these are basically metallized capacitors. However, really very good electrolytic capacitors can have these values too. Now it is also clear what letters and numbers like “m60” mean in the line where the capacitance is shown - this is the memory effect of the capacitor. Those. The lower this value, the better the quality of the capacitor.
Additional functions:
If you additionally make simple probes, you can measure the ESR of capacitors directly in the printed circuit board without desoldering and without harming the board components! In the diagram: resistor R1 0.6-2 W, 22±1% Ohm, low-loss polypropylene capacitor C1 type WIMO, D1 and D2 Schottky barrier diodes type BAT46.
Assembled devices and assembly kits with LCD display with blue backlight and white symbols are available:
In version with blue display The backlight turns on when powered by either a battery or an AC adapter. The current consumed from the power source during operation of the meter is 20...22 mA.
Electrical circuit diagram:
A video of the device in operation can be seen here:
Cost of a printed circuit board with mask and markings: 90 UAH
Cost of a programmed microcontroller: 110 UAH
Cost of the kit for assembling the measuring device: 430 UAH
Cost of assembled and tested device: 460 UAH
A brief description, assembly instructions, diagram and composition of the kit can be found
To order the device, please contact or
Good luck, peaceful skies, good luck! 73!
Stepan Mironov.
It has long been no secret that half of the failures in modern household appliances are associated with electrolytic capacitors.
Swollen capacitors are immediately visible, but there are also those that look quite normal. All faulty capacitors have a loss of capacity and an increased ESR value, or only an increased ESR value (the capacity is normal or higher than normal).
Calculating them is not so easy; you have to unsolder them, if several capacitors are connected in parallel, or if any shunt elements are connected in parallel to the capacitor being measured, check them and solder them back into working order. Many capacitors are glued to the board, located in hard-to-reach places and dismantling/installing them takes a lot of time. Even when heated, a faulty capacitor can temporarily restore its functionality.
Therefore, radio mechanics, and not only them, dream of having a device for checking the serviceability of electrolytic capacitors, in-circuit, without desoldering them.
I want to disappoint you, it’s 100% impossible. It is not possible to correctly measure capacitance and ESR, but it is possible to check the serviceability of an electrolytic capacitor without soldering, in many cases using an increased ESR value.
Faulty capacitors with increased ESR and normal capacity are common, but those with normal ESR and loss of capacity are not.
A 20% decrease in capacitance from the nominal value is not considered a defect, this is normal even for new capacitors, so for the initial defectiveness of an electrolytic capacitor, it is enough to measure the ESR. In-circuit capacitance readings, for information only and depending on the shunt elements in the circuit, may be significantly overestimated or may not be measured.
An indicative table of acceptable ESR values is given below:
Several versions of the ESR meter have been developed.
The ESR+LCF v3 meter (third version) was developed taking into account maximum capabilities for in-circuit measurements. In addition to the main ESR measurement (display Rx>x.xxx), there is an additional function for in-circuit ESR calculation, called "aESR" by the analyzer (display a x.xx).
The analyzer detects nonlinear areas when charging the measured capacitor (a working capacitor is charged linearly). Next, the estimated deviation is calculated mathematically and added to the ESR value.
When measuring a working capacitor, “aESR” and “ESR” are close in value. The display additionally shows the value “aESR”.
This function does not have a prototype, so at the time of preparing the main documentation, there was very little experience in using it.
At the moment, there are many positive reviews from different people with recommendations for its use.
This mode does not give a hundred percent result, but with knowledge of circuit design and accumulated experience, the effectiveness of this mode is great.
The result of an in-circuit measurement depends on the shunting influence of the circuit elements.
Semiconductor elements (transistors, diodes) do not affect the measurement result.
The greatest influence is exerted by low-resistance resistors, inductors, as well as other capacitors connected to the circuits of the measured capacitor.
In places where the shunting effect on the capacitor being tested is not large, the faulty capacitor can be measured well in the normal "ESR" mode, and in places where the shunting effect is large, the faulty capacitor (without desoldering) can only be calculated using the "analyzer - aESR".
It should be remembered that when making in-circuit measurements of healthy electrolytic capacitors, the "aESR" readings in most cases are slightly higher than the "ESR" readings. This is normal, since multiple connections to the capacitor being measured introduce error.
The most difficult places to measure are circuits with simultaneous shunting of many elements of different types.
In the diagram above, the faulty capacitor C2+1ohm is shunted by C1+L1+C3+R2.
When measuring such a capacitor, the ESR value is normal, but the analyzer shows “0.18” - this is exceeding the norm.
Unfortunately, it is not always possible to determine the serviceability of an electrolytic capacitor within the circuit.
For example: in motherboards it will not work to power the processor, the shunting there is too large. A radio mechanic, as a rule, repairs equipment of the same type, and over time he gains experience, and he already knows exactly where and how electrolytic capacitors are diagnosed.
So, what can my meter do?
In ESR mode, you can measure constant resistances of 0.001 - 100 Ohm; measuring the resistance of circuits with inductance or capacitance is impossible (since the measurement is performed in pulse mode and the measured resistance is shunted). To correctly measure such resistances, you must press the “+” button (in this case, the measurement is performed at a constant current of 10 mA). In this mode, the range of measured resistances is 0.001 - 20 Ohm.
- In ESR mode, pressing the “L/C_F/P” button turns on the in-circuit analyzer function (see below for a detailed description).
- In frequency meter mode, when the “Lx/Cx_Px” button is pressed, the “pulse counter” function is activated (continuous counting of pulses arriving at the “Fx” input). The counter is reset using the “+” button.
- Low battery indication.
- Automatic shutdown - about 4 minutes (in ESR mode - 2 minutes). After the idle time has expired, the inscription “StBy” lights up and within 10 seconds, you can press any button and work will continue in the same mode.
In modern technology, electrolytic capacitors are often bypassed with inductance less than 1 μH and ceramic capacitors. In normal mode here, the meter is not able to detect a faulty electrolytic capacitor without desoldering. For these purposes, an in-circuit analyzer function has been added.
The analyzer detects nonlinear areas when charging the measured capacitor (a working capacitor is charged linearly). Next, the expected deviation is calculated mathematically and added to the value ESR(Rx) = aESR(a). The display also shows the aESR (a) value. This function is most effective when measuring capacitances above 300 µF. To enable this function, you must press the “L/C_F/P” button.
“The heart of the meter is the PIC16F886-I/SS microcontroller. This meter can also operate PIC16F876, PIC16F877 microcontrollers without changing the firmware.
LCD indicator based on the HD44780 controller, 2 lines of 16 characters.
Controller - PIC16F886-I/SS.
Transistors BC807 - any P-N-P, similar in parameters.
Op-amp TL082 - any of this series (TL082CP, AC, etc.). It is possible to use the MC34072 op-amp. The use of other op-amps (with different speeds) is not recommended.
Field effect transistor P45N02 - 06N03, P3055LD, etc., fits almost any computer motherboard.
Choke L101 - 100 µH + -5%. You can make it yourself or use a ready-made one. The diameter of the winding wire must be at least 0.2mm.
S101 - 430-650pF with low TKE, K31-11-2-G - can be found in the KOS of domestic 4-5 generation TVs (KVP circuit).
C102, C104 4-10uF SMD - can be found in any old Pentium-3 computer motherboard near the processor, as well as in a Pentium-2 boxed processor.
BF998 - can be found in VCRs, TVs and VCRs GRUNDIK.
SW1 (size 7*7mm) - pay attention to the pinout, there are two types. The PCB layout corresponds to Fig. 2.
The printed circuit board is made of single-sided fiberglass.
At the same time, the printed circuit board serves as the base for the housing. 21mm wide fiberglass strips are soldered around the perimeter of the board.
The covers are made of black plastic.
There are control buttons on top, and in front there are three TULIP type sockets for a removable probe. For the “R/ESR” mode - a higher quality socket.
A metal tulip-type plug was used as a probe. A needle is soldered to the central pin.
From the available material, a brass rod with a diameter of 3 mm can be used to make a needle. After some time, the needle oxidizes and to restore reliable contact, it is enough to wipe the tip with fine sandpaper.
Below in the archive there are all the necessary files and materials for assembling and configuring this meter.
Good luck to everyone and all the best!
miron63.
Archive ESR+LCF v3 meter.
When repairing equipment, radio mechanics specialists are faced with various problems - damaged tracks on boards, oxidation, burnt-out elements, swollen capacitors. These faults are clearly visible during the initial inspection of the equipment and eliminating them using the most basic tools of any engineer is not difficult. But there are cases in which a visual inspection is not enough.
Capacitors come in different capacities, both very large (4000, 10000 µF) and very small (0.33 µF, for example, such parts are actively used in assembling components for various office equipment). And if the swelling of the top cover of the former is clearly visible due to their size, then with the latter, identifying their malfunction can cause a lot of problems.
A simple device for testing capacitors will help with this - ESR meter. It is not difficult to make it with your own hands if you have sufficient knowledge of circuit design. It can be either a standalone device or made as an attachment to a digital multimeter. With its help, you can easily identify faults such as breakdown and drying out.
Electrolytic capacitors have a number of parameters that are important for their correct operation in the device circuit. This is its capacitance, the dielectric resistance between the terminals and the body, and its own inductance, equivalent series resistance or, in the American style, Equivalent Series Resistance. ESR is the resistance of the capacitor plates and its legs, with which it is soldered to the board, and the terminals.
There are special formulas for calculating this indicator, but no one uses them in real practice. It is much easier to assemble a device to measure it, and compare the results obtained with the ESR table of electrolytic capacitors, which shows the values in milliohms, depending on the characteristics of the parts - capacitance and supported voltage.
Capacitors are used almost everywhere. Not a single device circuit with even minimal complexity can do without them.
In personal computers, they are found in power supplies, monitors, near important components of motherboards - network and sound chips, in the power supply system of the processor, south and north bridges, and RAM.
In speaker systems and network equipment (routers, switches, for example), they are found near amplifiers and LAN ports. All of them provide stable power to these elements, and the slightest problems with power supply, as is known, can lead to both problems in operation - freezing, braking, and a banal refusal to work.
Dried and broken capacitors cannot be detected by simple inspection, so it is the ESR meter that can determine the cause of the malfunction. To do this, the suspected parts are desoldered from the board and checked with the device. It is not recommended to check them without soldering them - the indicators in this case may be too inaccurate. If the resistance value is too high, the component should be replaced with one with the lowest ESR.
At the core ESR meter circuits lies a pulse generator chip of the K561LN2 type, operating at a frequency of up to 120 kHz. For additional convenience, the microcircuit itself can not be soldered directly into the board, but a special panel with the required number of legs can be used. This will allow you to quickly replace a failed part and replace it without additional operations with a soldering iron and solder suction. As an analogue of this generator, you can use the K1561LN2, which is similar in characteristics.
The frequency is adjusted by a circuit consisting of a resistor and a capacitor. The ESR measurement is adjusted and configured using a trimming resistor.
The power supply is either a standard CR2032, which produces a voltage of up to 3 volts, or, if this is not enough for operation, a 9-volt rechargeable battery connected through a special terminal (these can be found in some self-powered watches, for example, or in old batteries Crohn's type). The AC voltage meter includes a multimeter, which must be switched to the appropriate mode, and germanium diodes.
Capacitor tester assembly can be produced both on a breadboard measuring approximately 4 by 6 centimeters, and on special printed circuit boards. The second option will be a little more expensive, but its advantage is the presence on the board of symbols of all the necessary elements and the tracks connecting them.
Printed circuit boards are made of foil PCB and before mounting the elements, the contacts on them must be tinned with solder.
When using breadboards, the elements are placed and connected independently. To create the circuit, wires of sufficient thickness with fluoroplastic insulation are used to prevent damage due to heat.
Both purchased and homemade probes can be used as probes. In the second case, you need to independently take care of the good conductivity of the material used and the sufficient thickness of the wire going to the multimeter. It is not recommended to use long wires, more than 10 centimeters.
Possible shortcomings and comments on the operation of this device:
The first and second disadvantages have a common solution - it is enough to install a stabilizer in the circuit, powered directly from the battery, and two capacitors. This increases the reliability and accuracy of the device, which makes it possible to discard situations in which, if the resistance of the element being measured was too low, the multimeter signaled a short circuit instead of the expected value.
After mounting the device on the board and performing initial tests, it must be calibrated. To do this, you will need an oscilloscope and a set of resistors for adjustment with a value from 1 to 80 Ohms. Calibration procedure:
After calibration, the device can be used. It will help in detecting reactance related faults. They cannot be diagnosed any other way.
