The barometer circuit for measuring atmospheric pressure is built using an MPXHG6115 pressure sensor. The sensor itself provides a voltage at its output proportional to air pressure. The operating range covers atmospheric pressure (90 - 110 kPa) at sea level. The minimum operating air pressure of the sensor is 15 kPa, which allows it to be used even in mountainous areas. To do this, however, you need to recalculate the resistors on its board. For atmospheric pressure in an area near sea level, the sensor output voltage range is 3.625 - 4.55 volts. In the analog part of the circuit (shaded in the diagram), a linear voltage in the range of 0 - 5 V is generated at the output, which is in the normal range of the microcontroller ADC. The matching is done using two op-amps. The left one (in the diagram) provides the optimal load resistance for the sensor (51 kOhm) and inverts the reference voltage of about 2.5 V. The reference voltage is obtained using a voltage divider consisting of two 11.5 k resistors (1% accuracy). The right op-amp provides the necessary voltage scaling and initial setting to 0. We recommend using a dual OPA2374.
Specifications
- Measuring range: 700 - 800 mmHg
- Supply voltage: 5 volts
- Current consumption: 40 mA
The zoom sensor and analog amplifier are assembled on a small printed circuit board. It connects to the main board using 3 wires. The test circuit consists of a microcontroller and an LCD module with an interface mounted on its rear side. The interface card makes all communications with the PIC using only two wires and its software implements a simplified version of the standard I2C interface. The PIC16F84 controller program assigns its RC3 pin input to the ADC input. It simply calculates the pressure based on the input voltage according to the formula, converts it into BCD and displays it on the screen.
I remember when I was very little, my grandfather never listened to the weather forecast on the radio, he always looked at his old needle barometer, he had at least two needles (I don’t remember exactly, because so many years have passed), and he was never wrong!
So I have long wanted to have a barometer on my farm, but it’s still not possible, it’s expensive, I didn’t come across it, or there were some other obstacles. But then I started working on microcontrollers and it became possible to make a barometer myself.
I saved some money from my beloved wife’s stash and purchased sensors, MPX4115AP (pressure sensor) and HIH-4000-004 (humidity sensor), why exactly these? Yes, simply, because there is a lot of information on them on the Internet, and they were on sale, although they were expensive. The lion's share of the cost of the entire device came from them.
Both sensors are analog, which means that the barometer should be a two-input voltmeter, with the ADC readings adjusted in mmHg. (millimeters of mercury), and % (percentage of air humidity). The actual conversion of ADC readings into mmHg. , and % I conscientiously took from the article “Small DIY weather station” - http://www.avispro.com.ua/doc.php?id=1172
But the design presented in the article seemed redundant to me, and I wanted to make it simpler and definitely use LED indicators, since they glow and are large in size, which means they will be clearly visible from afar, and in any lighting, and they consume much less current than the LCD backlight.
I used the BA56-12SRWA indicator (LED seven-segment, 3 digits OA), 2 pieces. They are super bright, i.e. current consumption can be further reduced.
You can read about how to use atmospheric pressure and air humidity values in weather forecasting, for example, here - http://www.meteopost.com/info/Pressure/
This is the resulting diagram:
The board layout is like this:
On the printed circuit board there is a common bus - digital and analog are separated.
The power supply is also divided into analog and digital, and is supplied through 25 µH chokes. to analog circuits, and the conductor in a ferrite tube to digital ones.
At the ADC input there are 0.33 µF capacitors to the analog ground, and a 750 ohm resistor to the sensors. These are filters to reduce all kinds of noise at the inputs.
The microcontroller pins AVCC and AREF are shunted with 0.1 μF ceramic capacitors, and another 10.0 μF tantalum capacitors (yellow ones from old motherboards).
In order for the air humidity readings to be correct, it must be taken outside the room (outside), and connected to the board with a cable (preferably shielded), and of course protected from direct exposure to precipitation, because the sensor crystal is completely open. It is not necessary to move the pressure sensor outside the board at all.
This program, of course, is not a standard, but it’s quite suitable as an option for beginners
Of course, you can add suppression of an insignificant zero in the humidity indicator, it’s not difficult, you can dig around and correct something else, because there is no limit to perfection.
I give readers complete freedom to improve the code.
The article is intended for people who like to create something with their own hands, just for the soul and moral satisfaction.
Note: Commercial use of materials from this article is prohibited!
The code is written in CodeWizardAVR V2.04.4a
The board is routed in Sprint-Layout 5.0
The diagram is drawn in Splan7.0.0.8_portable_rus
In healthy people, a change in weather does not have much effect on their well-being, but weather-dependent people react very painfully to any change in weather or atmospheric pressure.
The barometer-alarm proposed in the article is intended to inform weather-dependent people in real time about the current value of atmospheric pressure, when the atmospheric pressure value goes beyond the established limits and its sharp jumps.
The appearance of the device is shown in Figure 1.
Figure 1. Appearance of the device
The user independently sets the boundary values - minimum and maximum thresholds.
If the atmospheric pressure exceeds the maximum threshold or falls below the minimum threshold, the device will emit intermittent sound signals and “Threshold” light signals.
After the sound signals are repeated five times, the sound turns off, and the light signal will be given until the atmospheric pressure returns to the specified limits.
The user sets the magnitude of the controlled jump in atmospheric pressure for a set time interval.
In cases where the atmospheric pressure in a given time interval deviates by an amount exceeding the controlled jump, the device will give intermittent sound signals and light signals “Jump”.
After the beeps are repeated five times, the sound will turn off and the light will continue until the barometric pressure returns to a level where the surge is considered uncontrollable.
Atmospheric pressure values are presented in the device in “mmHg”. Art."
Demo video
Schematic diagram of the device.
The electrical circuit diagram of the device is shown in the figure (Figure 2).
The device is assembled on an ATmega8 microcontroller.
Resistor R1 and capacitor C3 provide a hardware reset of the MK when power is applied.
Capacitors C2 and C1 protect the power circuits from high-frequency interference and power surges.
The atmospheric pressure value comes from the BMP1 sensor (GY68 BMP180).
The pressure sensor is controlled via the TWI (I2C) interface.
The sensor inputs are connected to the supply voltage by resistors R8 and R10.
The Nokia 5110's LCD screen is used to display information. The screen displays information about the current atmospheric pressure, as well as device settings.
Operational indication of the state of atmospheric pressure is carried out using LEDs VD1..3 (“Normal”, “Threshold”, “Jump”).
Sound signaling is carried out using a low-frequency amplifier using transistors VT1..2 and loudspeaker SP1. The sound volume can be adjusted using variable resistor R5.
The device is configured using the buttons SA2 ("Install"), SA3 ("+"), SA4 ("-").
When you press the SA5 (“Screen”) button, the main screen with the current atmospheric pressure value is displayed.
Attention! Fuses for tuning the MK: HIGH=0xD9, LOW=0xE1.
Figure 2. Electrical circuit diagram
Software.
The program for MK is written in C language in the AtmelStudio environment (Version 7.0.1006).
The program code is given in the Appendix (SignalBarometer.rar Archive of the Atmel Studio 7 project in C).
In order to reduce the power consumption of the device, the method of “falling asleep” of the MK in the “power-save” mode was used. At the same time, the current consumption in sleep mode is reduced to 20 μA.
According to calculations, this allows you to use two 1.5 Volt AA batteries for 4 months.
To wake up the MK from the “power-save” mode, an internal asynchronous timer-counter No. 2 is used, which runs constantly.
The counter timer master oscillator uses a quartz resonator Y1 with a resonance frequency of 32768 Hz.
Timer-counter No. 2 is configured so that every 8 seconds it overflows and calls an interrupt, which “wakes up” the MK.
After waking up from timer-counter No. 2, the MK finds out whether 10 minutes have passed since the previous awakening. If not, then the MK gives a light signal “Normal”, “Threshold” or “Jump” depending on the condition that developed after the previous measurement, and falls asleep again for 8 seconds.
If 10 minutes have passed since the previous measurement, then the MK sends a command to the pressure sensor to take measurements, receives a response from the sensor, processes the data, comparing the received value with threshold values or conditions for recording a jump, and issues a light signal “Normal”, “Threshold” or “ Jump" and beep if necessary. And again he “falls asleep” for 8 seconds.
The second source of awakening the MK is an external interrupt at the INT1 input, which occurs when the “Screen” button is pressed.
MK, having awakened and found out that it was “awakened” by the “Screen” button, turns on the liquid crystal display of the Nokia 5110 and displays on it the current value of atmospheric pressure and other information.
The screen will display information until the Screen button is released. After releasing the “Screen” button, the MK turns off the display by issuing the “power-down” command to it, then the MK “falls asleep” itself.
The third and final source of awakening the MK is an external interrupt at the INT0 input, which occurs when the “Set” button is pressed.
MK, having woken up and found out that he was “awakened” by the “Install” button, turns on the liquid crystal display of the Nokia 5110 and displays the device settings parameters on it.
Clicking the “Set” button again moves the cursor to the next parameter. Pressing the “+” and “-” buttons changes the value of the parameter on which the cursor is positioned.
After pressing the “Install” button on the last parameter, the MK turns off the display and “falls asleep” until the next awakening.
Device design.
The device is made in the housing of a distribution box “Tuco 79x79x32, for open wiring, white (65004)” (Figure 3).
Figure 3. Tyco distribution box (65004).
The board is made on one-sided foil fiberglass. Board size 72x72mm. The location of the parts on the board is shown in Figure 4. There are 9 (!) jumpers on the top of the board. They are highlighted in different colors. If you use a double-sided PCB, the jumpers can be converted into tracks.
Figure 4. Board. View from above.
The PCB layout is shown in Figure 5. The image is mirrored.
Figure 5. PCB layout.
The speaker is attached to the back wall of the device case. The assembly components are shown in Figure 6.
Figure 6. Device components.
Batteries (two AA cells) are placed in the battery compartment in specialized holder-beds (Figure 7).
Figure 7. Battery placement.
Device setup.
Figure 8 shows the controls for setting up the device.
To enter the mode, click the “Install” button. The display will show the adjustable parameters.
Use the “+” and “-” buttons to set the required parameter value.
To proceed to setting the next parameter, click the “Install” button.
To exit the setup mode, press the “Setup” button several times.
Top Options<порог>", "Lower<порог>» “Leap” are specified in mmHg. Art., the “interval” for measuring the jump is set in hours. .
Figure 8. Device settings controls.
The volume of the sound signal is adjusted using the “Volume” potentiometer. To make adjustments, you must use a miniature Phillips screwdriver.
If necessary, a potentiometer can be installed with an external handle for ease of adjustment.
Operation of the device.
After switching on, the device is ready for use and immediately takes the first measurement of atmospheric pressure. In this case, the screen is darkened, and the measurement results are displayed using the LED indicators “Normal”, “Threshold” or “Jump”.
The indicator corresponding to the measurement and analysis result produces five short flashes every 8 seconds.
When transitioning from the “Normal” state to the “Threshold” or “Jump” state, a sound signal is generated. The alarm sounds for five 8 second intervals, starting with the interval following the state change.
For a detailed assessment of the current state, you must press and hold the “Screen” button. In this case, the information presented in Figure 9 will be displayed:
Current atmospheric pressure;
. the maximum and minimum pressure value measured over the time interval specified in the settings;
. magnitude of the jump in mmHg. as the difference between the values indicated in the previous paragraph;
. text description of the measurement result: NORMAL, THRESHOLD, JUMP.
After pressing the Screen button, the series of beeps will be interrupted.
Figure 9. Controls and indications during device operation.
After releasing the “Screen” button, the display will go out, and the device will continue to operate in normal mode, displaying the measurement and analysis results only on the LED indicators.
Application:
SignalBarometer2.dch Electrical diagram in DipTrace format
SignalBarometer2.dip PCB in DipTrace format
SignalBarometer.hex Load file
SignalBarometer.rar Archive of the Atmel Studio 7 project in C
Good luck in your creativity and all the best!
Download the archive.
David W. Bray
A description of the design of version 2.0 of an electronic barometer with a 1-Wire interface is given, which differs from the popular version 1.1a in double measurement accuracy.
As in version 1.1a, this design uses Motorola's MPX4115 integrated pressure sensor. Analog-to-digital conversion is performed by the DS2438 chip with a 1-Wire interface. In addition to these circuits, one operational amplifier, two voltage regulators, two diodes, an LED and several resistors and capacitors are used. Note that the original purpose of the DS2438 chip is a battery charge monitor.
The background to the development of version 2.0 can be found in the article http://davidbray.org/onewire/barometer.html.
Printed circuit board
As with the previous version 1.1a, the single-sided circuit board for the barometer version 2.0 was designed by Jim Jennings. The printed circuit board for version 2.0 is more universal; it can also be used to assemble the barometer circuit for version 1.1a.
Some subtleties
This circuit requires another additional power supply, which was missing in version 1.1a, since the MPX4115 pressure sensor requires a current of about 7 mA, which is more than what can be taken from the 1-Wire interface line.
The circuit provides a resolution (pressure measurement accuracy) of approximately 0.00417 inHg (0.1059 mm Hg or 0.0139 kPa) over an atmospheric pressure measurement range of 31.0 to 28.0 inHg (787.4 to 711.2 mm Hg or 105.0 to 95.0 kPa). Even greater measurement accuracy can be achieved by reducing the range of measured atmospheric pressure values.
Schematic diagram
This diagram does not show the connector. The complete diagram is given.
Description of the circuit diagram
The MPX4115 pressure sensor produces voltages ranging from 4.25 to 3.79 V at sea level and approximately 2.77 V to 2.45 V at 10,000 ft (3048 m). This exceeds the operating range of the input voltage of the LM358N operational amplifier when powered from a 5 V source. The fact is that the output signal of the pressure sensor is actually measured relative to its power bus, and not relative to ground, as would be much more convenient.
Fortunately, the DS2438's ADC can handle signals down to 10V, so when powering the op amp at 10V, the MPX4115's signals will be well matched to the DS2438's input range.
The signal from the output of the MPX4115 pressure sensor through an RC filter is fed to the input of the operational amplifier U1B with a gain of about 4. An adjustable voltage is supplied to the second input of the amplifier, which, summed with the output voltage of the pressure sensor, provides a level shift to match the ADC input.
Gain and offset are controlled by 10-turn trimmers. R3 sets the gain of U1A, and R4 controls the offset.
Please note that the output of the pressure sensor is connected to resistor R1 through a removable jumper. This is done so that the MPX4115 signal can be calibrated using an external voltage source.
Continue reading
Brief content of the magazine "Radio" No. 1:
Indicator of short-circuit turns in coils with ferromagnetic magnetic cores.
The device is designed to check for the presence of short-circuited turns of the windings of various electrical devices - transformers, direct and alternating current machines, magnetic amplifiers, etc.
Increased soldering iron power regulator.
The proposed device is designed to regulate the power of a soldering iron and other heating devices with a power of up to 100 watts. It can also be used to power lighting fixtures with incandescent lamps of the same power at reduced network voltage.
Interference simulator for testing network filters.
Schematic diagram and principle of operation of the original device, which can be used to comparatively evaluate the effectiveness of LC filters designed to operate in a 220 Volt alternating current network.
Dimmer with IR remote control.
The dimmer presented in the article is intended for use with incandescent lamps. They control it using a remote control from any household equipment. The device may be useful for people with disabilities.
LED lawn light includes electrical appliances.
The article describes the modification of an autonomous LED lawn lamp to automatically turn on networked electrical appliances, in particular lighting, at night. At the same time, the main function of the lamp is preserved.
Intercom.
This device is designed for conversations between two ordinary telephone sets. Communication via a two-wire line is provided at a distance of up to 1 km if its resistance does not exceed 500 Ohms.
Brief content of the magazine "Radio" No. 2:
Audio signal level indicator on ILT6-30M.
The author of the article shares his experience in using indicators from the Mayak MP-240S cassette recorder as a two-channel signal level indicator for an AF amplifier.
Ampere-voltmeter for laboratory power supply.
The device is designed to work together with any laboratory power supply. It not only shows the output voltage and current of the load, but also performs several additional functions that make the power supply more reliable.
Oscilloscope calibrator.
The proposed device is designed to calibrate amplitude and duration. The 1.999 Volt precision voltage source is based on an LM317T adjustable voltage regulator, and the duration calibrator is based on an ICM555IN integrated timer.
Network power supply based on a solar power battery.
The article describes an original low-power mains power supply with galvanic isolation from the network, in which the output voltage is created by a solar battery from a lawn lamp, illuminated by a garland of 14 white LEDs extracted from an LED lamp.
Chargers based on voltage stabilizer chips.
Detailed description, operating principle, as well as design features of simple chargers that are designed for charging lead-acid batteries.
Drawings, diagrams and assembly procedures for a microcontroller control unit, which was designed and manufactured to replace the standard control unit for the EVAN EPO-7.5/220 V electric heating boiler. It can also be used to control other electric heating devices.
Brief content of the magazine "Radio" No. 3:
The author of the article shares his experience in independently manufacturing a simple car stereo amplifier with a switching voltage converter.
Generator of a “drawn” signal.
A detailed overview of the manufacturing process of a signal generator based on the PIC16F873A-I/P microcontroller, which is capable of generating a signal literally drawn on a graphic display screen with a resolution of 128 x 64 pixels.
A device for experiments with Ni-Mh batteries of AA and AAA sizes.
The developed device makes it possible to identify batteries that have completely exhausted their resource, and to extend the life of the rest by selecting the optimal charging mode for each. The device is based on the ATmega8 microcontroller.
The proposed incubator allows you to automatically hatch chicks of four types of poultry: chickens, turkeys, ducks and geese. All actuators in it are powered by a constant voltage of 12 Volts, which allows the incubator as a whole to be powered not only from a 220 Volt household network, but also from a battery.
Control of an electric heating boiler.
End of the article published in Radio magazine No. 2 for 2014.
Running lights control unit.
The section “Electronics while driving” proposes the design of an electronic device that automatically turns on the running lights when the engine is running and turns them off when the low or high beam headlights are turned on.
Brief content of the magazine "Radio" No. 4:
Compact car amplifier.
The M-83x series multimeters are powered by a single battery.
The article offers options for powering popular multimeters of the M-83x series from one Ni-Cd or Ni-MH battery of AAA or 2/3 AAA size using a boost converter.
Low voltage automatic incubator.
End of the article published in Radio magazine No. 3 for 2014.
Radio alarm for hunters.
The author of the article shares his experience in independently manufacturing an original device that signals via radio about the movement of an animal in a controlled area.
Insect trap.
The proposed device can significantly reduce the number of flying insect pests. Several traps placed in the garden allow you to completely eliminate the use of chemicals.
Vehicle security system with satellite tracking of coordinates and transmission of alerts via GSM channel.
The article presents the original design of a car security system, which uses ready-made modules that have a rich set of functions and a design that allows installation with a conventional soldering iron.
QRP transceiver MA12.
A detailed description, as well as design features of the telegraph QRP transceiver for the 40 meter range, developed by the German shortwave DK1HE.
Brief content of the magazine "Radio" No. 5:
Stabilization of the mode of class AB amplifiers.
The article presents a method for automatically adjusting the bias voltage of push-pull amplifiers to stabilize the current consumed by the amplifier when the amplified signal passes through zero and at rest.
Audio player for MP3 and Opus formats.
The author of the article shares his experience in making a homemade portable player for music files of common formats from a microSD memory card. It is assembled on an STM32F407VGT6 microcontroller in a housing from a NOKIA 1100 cell phone.
Detailed description, operating principle, as well as design features of a matrix LED display for eight spaces. It can work with various sources of information, receiving data from them for display via the TWI (PC) interface.
Carbon monoxide concentration analyzer.
The proposed device is made on three microcircuits and five transistors. Gas sensor - electrochemical with liquid electrolyte TGS5042, visual indicator - three-digit LED LTD5122.
Stabilized voltage converter on the YX8018 chip.
The converter is designed to power various electronic devices that require a supply voltage of 2...5 Vol from one galvanic cell or Ni-Cd (Ni-MH) battery.
High precision thermometer with DS18S20 sensor.
A temperature measurement device is proposed, made on the ATmega8515 microcontroller and DS18S20 temperature sensor, characterized by simplicity of circuit and design with increased measurement accuracy (temperature readout resolution - 0.1 degrees Celsius).
Brief content of the magazine "Radio" No. 6:
The M-832 multimeter is powered by two batteries.
The author of the article proposes a method of powering 83x series multimeters from two high-capacity AA-size Ni-MH batteries, which can significantly extend the operating time of the devices without turning off the power.
Generator of two reference frequencies for broadcast transmitter synthesizers.
The generator is designed to generate signals of two switchable stable frequencies. It can be used as part of synthesizers for individual radio broadcasting when forming both a medium-wave broadcast grid with a step of 9 kHz and a short-wave broadcast with a step of 5 kHz.
Charging the battery using Peltier elements.
The device is based on the ATmega88-20AU microcontroller and contains, in addition to it, nine transistors.
Matrix LED display.
End of the article published in Radio magazine No. 5 for 2014.
Adjustable current stabilizer for powering high-power LEDs.
Design features and assembly process of the device, which is made on an integrated voltage stabilizer LM317T and transistor FMMT617 and is designed to power an LED assembly with a rated voltage of 12 Volts and a power of up to 18 Watts from a 15 Volt source.
Adjustable power supply.
Schematic diagram and operating principle of a homemade power supply, which is based on a unified step-down transformer TPP-251–220–50. The output voltage of the unit is adjustable within 0…12 Volts, load current 0.3…0.8 Amperes.
Brief content of the magazine "Radio" No. 7:
Two-channel stereophony - approaching the ideal. About playing stereo records through speakers.
The article presents a method for acoustic reproduction of stereophonic phonograms, which allows, without interfering with the sound engineer’s plan, to get rid of some of the shortcomings of this format and fully reveal its advantages in different rooms.
VHF range in VEF and Spidola receivers.
Description of the method of organizing the VHF range in radio receivers of the Spidola and VEF series using the TEA5710 microcircuit.
Device for monitoring EPS.
The device is designed to measure equivalent series resistance in two switchable intervals: in the first, you can test capacitors with a capacity of more than 1 μF (the ESR measurement limits are approximately from 1 to 30 Ohms), in the second - more than 10 μF (from 0.25 to 10 Ohms).
Portable MP3 player.
Design features and assembly process of a portable MP3 player, which allows you to play MP3 files with a digital audio stream speed of up to 256 Kbps and a duration of up to 99 minutes 59 seconds. The device is assembled based on a PIC18F4610-I/PT microcontroller and six microcircuits.
Welding machine "Malyutka".
A detailed description, principle of operation, as well as design features of a small-sized welding machine, which allows you to make welding connections of thin metal plates, work with it as an electrograph (“pencil”), and also make drawings of conductors of prototype printed circuit boards on foil-coated fiberglass laminate.
Brief content of the magazine "Radio" No. 8:
Automatic signal switch.
Drawings, diagrams and assembly procedures for a simple electronic switch that provides simultaneous switching of audio and video signals from two different sources.
Oscillating frequency generator with LCD indicator.
The article describes in detail the process of manufacturing a homemade device designed to determine the resonant frequency of an oscillating circuit or quartz resonator, the shape of the frequency response of an amplification path or filter in the frequency range from several hertz to ten megahertz.
Creeping line with text input using a computer keyboard.
This device is designed to display various advertisements and is intended for installation, for example, on the rear window of a car.
Laboratory power supply from a UPS.
The author of the article shares his experience in independently manufacturing a laboratory power supply from a faulty or outdated uninterruptible power supply.
A detailed overview of the manufacturing process of a simple device that ensures the stability of the soldering iron rod temperature set by the regulator when the mains voltage changes.
Clock-calendar on gas-discharge indicators.
The article talks about how to make an original watch with your own hands that shows the current time and date and has alarm functions. Their feature is the use of gas-discharge digital indicators IN-12.
Brief content of the magazine "Radio" No. 9:
Attachment to a frequency meter for resonant measurements.
Drawings, diagrams and assembly procedures for a homemade device, which is designed to determine the resonant properties of inductors, capacitors, as well as determine the capacitance of p-n junctions of varicaps, diodes and transistors.
Converter for powering a digital multimeter.
The article proposes a voltage converter option for powering a multimeter from one galvanic cell, as well as a Ni-Cd or Ni-MH battery.
Effective voltage stabilizer on the PIC16F684 microcontroller.
Design features and assembly process of the original device, which is designed for stepwise adjustment of the effective voltage value supplied to heating devices and incandescent lamps, and its stabilization during voltage fluctuations in the network.
Indication and control unit for a laboratory power supply and charger based on a computer power supply.
The proposed microcontroller display and control unit can be connected to any computer power supply that uses the TL494 chip or its equivalent, having previously modified this unit according to the recommendations of the article.
Capacitive liquid level meter.
The article provides a description of a device that measures the liquid level using the capacitive method. It is based on measuring the electrical capacitance between two electrodes placed in a reservoir of liquid that covers them to a greater or lesser extent.
Dependent switching on of electrical appliances.
The author of the article offers his own version of the device, which automatically supplies power to the slave device when the master is turned on.
Brief content of the magazine "Radio" No. 10:
Signal conditioner for subwoofer.
The author of the article offers a very simple and original circuit solution for achieving effective adjustments when generating signals for a subwoofer.
Low power high voltage source.
The presented high voltage source contains a relaxation generator based on a triac and a storage capacitor, a pulse high-voltage transformer and a rectifier using a voltage doubling circuit. The device is powered from the mains through a ballast capacitor.
Regulated power supply with protection.
The design of a homemade laboratory power supply, which provides for software setting of output voltage and current thresholds, exceeding which is impossible not only as a result of the most likely malfunctions of the unit, but also due to careless influence on its operational control elements.
Soldering iron tip temperature stabilizer.
The article presents a device, accessible for repetition, designed to maintain the optimal temperature of the soldering iron tip by measuring the resistance of the heater during short-term disconnections from the network.
Simple power regulator.
The device is designed to regulate power in a load with high inertia. The control method is to change the number of periods of the supply voltage supplied to the load.
Automation of the flush cistern.
The proposed device implements automatic, without any manual intervention, control of the flush cistern and ventilation in the toilet.
The chandelier is intended for general lighting of a living room or kitchen with an area of 10...14 m2 and creating decorative colored lighting in it. The brightness of the lighting and lighting effects are controlled using the IR remote control from the TV.
Brief content of the magazine "Radio" No. 11:
Welding machine with voltage booster and smooth current adjustment.
The article provides a description of a welding machine that is easy to manufacture and reliable in operation. It allows welding with both direct and alternating current, and in both cases stepwise and smooth adjustment is possible.
Aquarium control device.
The device measures water temperature with a DS18B20 sensor, and it is possible to connect two sensors and stabilize the temperature using the arithmetic mean value of their readings. It is also designed to connect LEDs that illuminate the aquarium.
SDU with ATtiny2313 microcontroller for 16 garlands.
The SDS is developed in two versions. The first controls only the LEDs located on its board and is intended for developing and debugging lighting effects programs. A microcontroller with a debugged program can be transferred to the board of the second version of the SDU, to which you can connect 16 lighting devices powered by a 220 Volt network.
LED chandelier "Rainbow".
End of the article published in Radio magazine No. 10 for 2014.
Bipolar voltage converter.
The schematic diagram and principle of operation of the device, which is built on the NSP1400ASN50T1 microcircuit, is powered by one galvanic cell or battery and provides an output voltage of +5 and –5 Volts.
Fan control device in a laboratory power supply.
The control device is made on the basis of an integrated voltage stabilizer KA78R12L-TF4-T, the peculiarity of which is the ability to turn it on and off by an external signal. In this case, it powers the fan motor, which turns on when the temperature inside the power supply reaches a preset value.
Brief content of the magazine "Radio" No. 12:
Preamplifiers and adders on TL064 microcircuits.
The article proposes options for AF preamplifiers based on an economical quad op-amp microcircuit, suitable for use in devices with battery or universal power supply.
Probe for testing oxide capacitors.
Schematic diagram and principle of operation of a homemade probe, which does not have a dial indicator. Its functions are performed by a line of LEDs, the glow length of which can be used to estimate the equivalent series resistance (ESR) of oxide capacitors.
Built-in current and voltage meter on PIC12F675.
The proposed device is designed for installation in various regulated power supplies. It displays the output voltage of the unit and its load current on its LED indicators.
Washbasin with touchless control.
