Quartz resonator probe circuit. Quartz resonator tester. Power supply for Frequency counter FC1100-M3

The reason for the creation of this device was a considerable number of accumulated quartz resonators, both purchased and soldered from different boards, and many did not have any markings. Traveling through the vast expanses of the Internet and trying to assemble and run various quartz tester circuits, it was decided to come up with something of our own. After many experiments with different generators, both on different digital logics and on transistors, I chose the 74HC4060, although it was also not possible to eliminate self-oscillations, but as it turned out, this does not create interference during the operation of the device.

Quartz meter circuit

The device is based on two CD74HC4060 generators (74HC4060 was not in the store, but judging by the datasheet they are even “cooler”), one operates at a low frequency, the second at a high one. The lowest-frequency ones I had were hour quartz, and the highest frequency was non-harmonic quartz at 30 MHz. Due to their tendency to self-excite, it was decided to switch the generators simply by switching the supply voltage, which is indicated by the corresponding LEDs. After the generators, I installed a logic repeater. It might be better to install capacitors instead of resistors R6 and R7 (I haven’t checked it myself).

As it turned out, the device runs not only quartz, but also all sorts of filters with two or more legs, which were successfully connected to the appropriate connectors. One “biped” similar to a ceramic capacitor was launched at 4 MHz, which was later successfully used instead of a quartz resonator.

The photographs show that two types of connectors are used to test radio components. The first is made from parts of sockets - for lead-out parts, and the second is a fragment of the board glued and soldered to the tracks through the corresponding holes - for SMD quartz resonators. To display information, a simplified frequency meter is used on the PIC16F628 or PIC16F628A microcontroller, which automatically switches the measurement limit, that is, the frequency on the indicator will be either in kHz or MHz. About the device details Part of the board is assembled on lead parts, and part on SMD. The board is designed for the Winstar single-line LCD indicator WH1601A (this is the one with the contacts at the top left), contacts 15 and 16, which serve for illumination, are not wired, but anyone who needs can add tracks and details for themselves. I didn’t turn on the backlight because I used a non-backlit indicator from some phone on the same controller, but at first there was a Winstar one. In addition to WH1601A, you can use WH1602B - two-line, but the second line will not be used. Instead of a transistor in the circuit, you can use any of the same conductivity, preferably with a larger h21. The board has two power inputs, one from a mini USB, the other through a bridge and 7805. There is also space for a stabilizer in another case.

Device setup

When tuning with the S1 button, turn on the low-frequency mode (the VD1 LED will light up) and by inserting a quartz resonator at 32768 Hz into the corresponding connector (preferably from the computer motherboard), use the tuning capacitor C11 to set the frequency on the indicator to 32768 Hz. Resistor R8 sets the maximum sensitivity. All files - boards, firmware, datasheets for the radio elements used and more, download in the archive. The author of the project is nefedot.

ARCHIVE:

The main feature of this frequency meter:
A highly stable TCXO (Thermal Compensated Reference Oscillator) is used. The use of TCXO technology allows you to immediately, without preheating, ensure the declared frequency measurement accuracy.

Technical characteristics of frequency meter FC1100-M3:

Distinctive features of frequency counters of the FC1100 line in particular:

Due to popular demand, an SMA-BNC adapter has been added to the kit, allowing the use of numerous standard cables, including oscilloscope probes with BNC connectors.
Dimensions of the printed circuit board of the FC1100-M3 device: 83mm*46mm.
Color TFT LCD display with backlight (diagonal 1.44" = 3.65 cm).
** The upper limit of the input signal is limited by the dissipation power of the B5819WS protection diodes (0.2 W * 2 pcs).

Reverse side of the FC1100-M3 frequency meter

Quartz frequency measurement mode in frequency meters FC1100-M2 and FC1100-M3

Comparator/former circuit for input signal 0...50 MHz.

Frequency divider circuit for input signal 1...1100 MHz.

Brief description of the FC1100-M3 frequency meter:

The FC1100-M3 frequency meter has two separate frequency measurement channels.
Both channels of the FC1100-M3 frequency counter operate independently of each other, and can be used to measure two different frequencies simultaneously.
In this case, both values ​​of the measured frequency are simultaneously displayed on the display.
"Input A" - (SMA-FEMALE connector type) Designed for measuring relatively high-frequency signals, from 1 MHz to 1100 MHz. The lower sensitivity threshold of this input is slightly less than 0.2 V, and the upper threshold is limited at 0.5...0.6 V by protective diodes connected back-to-back. There is no point in applying significant voltages to this input, because voltages above the opening threshold of the protective diodes will be limited.
The diodes used allow power dissipation of no more than 200 mW, protecting the input of the MB501L divider chip. Do not connect this input directly to the output of high power transmitters (over 100 mW). To measure the frequency of signal sources with an amplitude of more than 5 V, or significant power, use an external voltage divider (attenuator) or a low-capacity transition capacitor (units of picofarads) connected in series. If it is necessary to measure the frequency of the transmitter, usually a short piece of wire is enough as an antenna, included in the frequency meter connector, and located at a short distance from the transmitter antenna, or you can use a suitable “rubber band” antenna from portable radio stations connected to the SMA connector.

"Input B" - (SMA-FEMALE connector type) Designed for measuring relatively low-frequency signals, from 1 Hz to 50 MHz. The lower sensitivity threshold of this input is lower than that of “Input A” and is 0.6 V, and the upper threshold is limited by protective diodes at 5 V.
If you need to measure the frequency of signals with an amplitude of more than 5 V, use an external voltage divider (attenuator). This input uses the MAX999 high-speed comparator.
The input signal is supplied to the non-inverting input of the comparator, and resistor R42 is connected here, which increases the hardware hysteresis of the MAX999 comparator to a level of 0.6 V. A bias voltage is supplied to the inverting input of the MAX999 comparator, from a variable resistor R35, which sets the comparator response level. When measuring the frequency of noisy signals, it is necessary to rotate the knob of the variable resistor R35 to achieve stable frequency meter readings. The highest sensitivity of the frequency meter is realized in the middle position of the handle of the variable resistor R35. Rotation counterclockwise reduces, and clockwise increases, the threshold voltage of the comparator, allowing you to shift the threshold of the comparator to a noise-free section of the measured signal.

The "Control" button switches between the "Input B" frequency measurement mode and the quartz resonator testing mode.
In the quartz resonator testing mode, it is necessary to connect the quartz resonator being tested to the extreme contacts of the “Quartz Test” panel, with a frequency from 1 MHz to 25 MHz. The middle contact of this panel does not need to be connected; it is connected to the “common” wire of the device.

Please note that in the quartz resonator testing mode, in the absence of the tested quartz in the panel, constant generation is observed at a relatively high frequency (from 35 to 50 MHz).
Also, it should be noted that when connecting the quartz resonator under study, the generation frequency will be slightly higher than its typical frequency (within a few kilohertz). This is determined by the parallel excitation mode of the quartz resonator.
The quartz resonator testing mode can be successfully used to select identical quartz resonators for ladder multi-crystal quartz filters. At the same time, the main criterion for selecting quartz resonators is the closest possible generation frequency of the selected quartz.

Connectors used in the FC1100-M3 frequency meter:

Power supply for Frequency Counter FC1100-M3:

The FC1100-M3 frequency meter is equipped with a standard Mini-USB connector with a supply voltage of +5.0 Volts.
Current consumption (no more than 300 mA) - ensures compatibility with most USB voltage power supplies.
The kit includes a “Mini-USB” “USB A” cable, which allows you to power the frequency meter from any device that has such a connector (Personal Computer, Laptop, USB-HUB, USB Power Supply, USB AC Charger) and so on.

For autonomous power supply of the FC1100-M3 Frequency Meter, widely used “Power Bank” batteries with built-in Lithium-Polymer batteries, usually used to power equipment with USB connectors, are optimally suited. In this case, in addition to obvious convenience, as a bonus you get galvanic isolation from the network and/or power supply, which is important.

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about arrival at the warehouse

A set of components for assembling a frequency meter with the function of a quartz resonator tester.

Simple and inexpensive, developed on the basis of a PIC microcontroller with the ability to take into account the frequency shift of superheterodyne receivers in measurements with a five-digit LED indicator, convenient and intuitive.

Functions

• The display resolution automatically switches to ensure maximum reading accuracy with a 5-digit display.
  The measurement duration (gate time) during which the input pulses are counted is also automatically changed.
• If the frequency meter is used for measurements on shortwave receivers or transmitters, you may need to add or subtract the frequency offset value from the frequency being measured. The offset frequency is in many cases equal to the intermediate frequency, since the frequency meter is usually connected to the receiver's variable frequency generator.
• To measure the oscillating frequency of quartz, simply connect it to the connector labeled “Crystal under test”

Additional Information

Main features:

Frequency measurement range: 1 Hz - 50 MHz

Measurement of quartz for general use in generation frequency in the range: 1 MHz - 50 MHz

Automatic band switching

Programmable settings for the added and subtracted value of the frequency shift during adjustments and measurements in VHF receivers and transmitters.

Maximum input voltage 5 Volts

Energy saving mode when powered from an autonomous current source

It is possible to use 5V from the USB interface

Minimum number of components, simple assembly and configuration

Questions and answers

• Hello, can I order this product in quantity of 1 piece?
  • Yes, of course you can!
• Hello. What voltage range of the measured frequency is allowed at the input in frequency meter mode?
  • TTL logic level, up to 5 Volts
• Hello. What is the maximum input voltage for this frequency meter?
  • 5 Volt
• Hello, when will this construction set go on sale, in particular in the Chip and Dip store?
  • Good afternoon The product is now at the stage of acceptance into the finished goods warehouse, I think within a week it will be available for order through our online store. Regarding Chip and Dip, this question should be asked directly to them.
• Good day! Tell me what's the matter. The frequency meter shows the same number all the time. 65.370
  • This is the first time we have heard about such a problem. When assembled correctly, the device starts working immediately and does not require configuration. See installation and ensure correct installation of all components. The value of constant resistors must be checked with a multimeter before installation.

Oscillations play one of the most important roles in the modern world. So, there is even a so-called string theory, which claims that everything around us is just waves. But there are other options for using this knowledge, and one of them is a quartz resonator. It just so happens that any equipment periodically fails, and they are no exception. How can you make sure that after a negative incident it still works as it should?

Let's say a word about the quartz resonator

A quartz resonator is an analogue of an oscillatory circuit based on inductance and capacitance. But there is a difference between them in favor of the first. As is known, the concept of quality factor is used to characterize an oscillatory circuit. In a quartz-based resonator it reaches very high values ​​- in the range of 10 5 -10 7 . In addition, it is more efficient for the entire circuit when temperature changes, which translates into longer service life for parts such as capacitors. The designation of quartz resonators in the diagram is in the form of a vertically located rectangle, which is “sandwiched” on both sides by plates. Externally in the drawings they resemble a hybrid of a capacitor and a resistor.

How does a quartz resonator work?

A plate, ring or bar is cut from a quartz crystal. At least two electrodes, which are conductive strips, are applied to it. The plate is fixed and has its own resonant frequency of mechanical vibrations. When voltage is applied to the electrodes, compression, shear, or bending occurs due to the piezoelectric effect (depending on how the quartz was cut). The oscillating crystal in such cases does work like an inductor. If the frequency of the voltage that is supplied is equal to or very close to its natural values, then less energy is required at significant differences to maintain operation. Now we can move on to highlighting the main problem, which is why this article about a quartz resonator is being written. How to check its functionality? 3 methods were selected, which will be discussed.

Method No. 1

Here the KT368 transistor plays the role of a generator. Its frequency is determined by a quartz resonator. When power is supplied, the generator starts working. It creates impulses that are equal to the frequency of its main resonance. Their sequence passes through a capacitor, which is designated as C3 (100r). It filters the DC component, and then transmits the pulse itself to an analog frequency meter, which is built on two D9B diodes and the following passive elements: capacitor C4 (1n), resistor R3 (100k) and a microammeter. All other elements serve to ensure the stability of the circuit and so that nothing burns out. Depending on the set frequency, the voltage on capacitor C4 may change. This is a fairly approximate method and its advantage is ease. And, accordingly, the higher the voltage, the higher the frequency of the resonator. But there are certain limitations: you should try it on this circuit only in cases where it is within the approximate range of three to ten MHz. Testing quartz resonators that goes beyond these values ​​usually does not fall under amateur radio electronics, but below we will consider a drawing whose range is 1-10 MHz.

Method number 2

To increase accuracy, you can connect a frequency meter or oscilloscope to the generator output. Then it will be possible to calculate the desired indicator using Lissajous figures. But keep in mind that in such cases the quartz is excited, both at harmonics and at the fundamental frequency, which, in turn, can give a significant deviation. Look at the diagrams below (this one and the previous one). As you can see, there are different ways to look for frequency, and here you will have to experiment. The main thing is to follow safety precautions.

Checking two quartz resonators at once

This circuit will allow you to determine whether two quartz resistors that operate within the range of one to ten MHz are operational. Also, thanks to it, you can recognize the shock signals that go between frequencies. Therefore, you can not only determine the performance, but also select quartz resistors that are most suitable for each other in terms of their performance. The circuit is implemented with two master oscillators. The first of them works with a ZQ1 quartz resonator and is implemented on a KT315B transistor. To check operation, the output voltage must be greater than 1.2 V, and press the SB1 button. The indicated indicator corresponds to a high level signal and a logical unit. Depending on the quartz resonator, the required value for testing can be increased (the voltage can be increased each test by 0.1A-0.2V to that recommended in the official instructions for using the mechanism). In this case, output DD1.2 will be 1, and DD1.3 will be 0. Also, indicating the operation of the quartz oscillator, the HL1 LED will light up. The second mechanism works similarly and will be reported by HL2. If you start them simultaneously, the HL4 LED will also light up.

When the frequencies of two generators are compared, their output signals from DD1.2 and DD1.5 are sent to DD2.1 DD2.2. At the outputs of the second inverters, the circuit receives a pulse-width modulated signal in order to then compare the performance. You can see this visually by flashing the HL4 LED. To improve accuracy, a frequency meter or oscilloscope is added. If the actual indicators differ by kilohertz, then to determine a higher frequency quartz, press the SB2 button. Then the first resonator will reduce its values, and the tone of the light signal beats will be less. Then we can confidently say that ZQ1 is higher frequency than ZQ2.

Features of checks

When checking always:

1. Read the instructions that came with the quartz resonator;
2. Follow safety precautions.

Possible causes of failure

There are quite a few ways to disable your quartz resonator. It’s worth familiarizing yourself with some of the most popular ones to avoid any problems in the future:

1. Falls from a height. The most popular reason. Remember: you must always keep your work area in order and monitor your actions.
2. Presence of constant voltage. In general, quartz resonators are not afraid of it. But there were precedents. To check its functionality, connect a 1000 mF capacitor in series - this step will return it to operation or avoid negative consequences.
3. The signal amplitude is too large. This problem can be solved in different ways:

• Move the generation frequency slightly to the side so that it differs from the main indicator of the mechanical resonance of quartz. This is a more complex option.
• Reduce the number of volts that power the generator itself. This is an easier option.
• Check whether the quartz resonator is really out of order. So, the reason for the decrease in activity may be flux or foreign particles (in this case, it is necessary to clean it thoroughly). It may also be that the insulation was used too actively and it lost its properties. To check this point, you can solder a “three-point” on the KT315 and check it with an axle (at the same time you can compare the activity).

Conclusion

The article discussed how to check the performance of such elements of electrical circuits as the frequency of a quartz resonator, as well as their properties. Methods for establishing the necessary information were discussed, as well as possible reasons why they fail during operation. But to avoid negative consequences, always work with a clear head - and then the operation of the quartz resonator will be less disturbing.

The reason for the creation of this device was a considerable number of accumulated quartz resonators, both purchased and soldered from different boards, and many did not have any markings. Traveling through the vast expanses of the Internet and trying to assemble and launch various ones, it was decided to come up with something of our own. After many experiments with different generators, both on different digital logics and on transistors, I chose the 74HC4060, although it was also not possible to eliminate self-oscillations, but as it turned out, this does not create interference during the operation of the device.

Quartz meter circuit

The device is based on two CD74HC4060 generators (74HC4060 was not in the store, but judging by the datasheet they are even “cooler”), one operates at a low frequency, the second at a high one. The lowest-frequency ones I had were hour quartz, and the highest frequency was non-harmonic quartz at 30 MHz. Due to their tendency to self-excite, it was decided to switch the generators simply by switching the supply voltage, which is indicated by the corresponding LEDs. After the generators, I installed a logic repeater. It might be better to install capacitors instead of resistors R6 and R7 (I haven’t checked it myself).

As it turned out, the device runs not only quartz, but also all sorts of filters with two or more legs, which were successfully connected to the appropriate connectors. One “biped” similar to a ceramic capacitor was launched at 4 MHz, which was later successfully used instead of a quartz resonator.

The photographs show that two types of connectors are used to test radio components. The first is made from parts of sockets - for lead-out parts, and the second is a fragment of the board glued and soldered to the tracks through the corresponding holes - for SMD quartz resonators. To display information, a simplified frequency meter is used on the PIC16F628 or PIC16F628A microcontroller, which automatically switches the measurement limit, that is, the frequency on the indicator will be either kHz or in MHz.

About device details

Part of the board is assembled on lead parts, and part on SMD. The board is designed for the Winstar single-line LCD indicator WH1601A (this is the one with the contacts at the top left), contacts 15 and 16, which serve for illumination, are not wired, but anyone who needs can add tracks and details for themselves. I didn’t turn on the backlight because I used a non-backlit indicator from some phone on the same controller, but at first there was a Winstar one. In addition to WH1601A, you can use WH1602B - two-line, but the second line will not be used. Instead of a transistor in the circuit, you can use any of the same conductivity, preferably with a larger h21. The board has two power inputs, one from a mini USB, the other through a bridge and 7805. There is also space for a stabilizer in another case.

Device setup

When tuning with the S1 button, turn on the low-frequency mode (the VD1 LED will light up) and by inserting a quartz resonator at 32768 Hz into the corresponding connector (preferably from the computer motherboard), use the tuning capacitor C11 to set the frequency on the indicator to 32768 Hz. Resistor R8 sets the maximum sensitivity. All files - boards, firmware, datasheets for used radio elements and more, download in the archive. Author of the project - nefedot.

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