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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING The radio call controls the pump. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Home, household, hobby The creation of devices for remote electronic control of various actuators was a promising direction in radio engineering back in the days of my "pioneer" childhood in the 1980s. Then, under the guidance of mentors, we enthusiastically assembled such equipment based on discrete elements. Usually it had a range of 5 - 6 m and at the same time it barely fit in a box measuring 300x300x150 mm. If it was possible to assemble and set up at least half a month the equipment for remote control of a boat or aircraft model with a command transmission range of 20 - 30 m, this was considered by us (10 - 12-year-old children) a great success. This direction has not lost its relevance today. But now it is easier to do this, because you can not assemble it in detail, but purchase a ready-made device for transmitting a signal over a radio channel in a store (using an IR channel, a laser beam, etc.), and for a very "democratic" price and adjust it to your own tasks by improving it. Of course, it is regrettable that, in this case, the creative component of the creation of the device, which involves painstaking understanding of the issue of its functioning - from development to adjustment, is practically nullified, which not only improves qualifications, but also opens the door to deep fundamental research. But, on the other hand, why waste time and "suffer" - to create a device from scratch, if you can improve the finished one, expanding its range. This approach is acceptable for professionals or those who need to quickly get the practical result of their work. These are the realities of the times, and we have to adapt to them to a reasonable extent. I invite readers to consider a remote control device that operates over a radio channel at a distance of more than 100 m and allows you to automate the switching on and off of an injection submersible water pump that supplies water to a house, a bathhouse, a barn and other buildings in a personal plot from a source - a village well. The device is based on a wireless radio call purchased at a household goods store worth 192 rubles. In passing, I note that the finished equipment for controlling the pumping station (without wires) costs over 3000 rubles. Draw your own conclusions. True, it is also capable of additionally carrying out automatic control of the water pressure in the circuit when it decreases (they open a tap in the house), commands the filling of the reserve tank, and some models also heat the water. But in our case, these functions were redundant.
Wireless calls may have a different appearance, but their mandatory elements are the transmitter and receiver of the radio signal. Typically, these wireless calls operate on the 433 MHz frequency and do not cause interference. In addition, their transmitter power is low. The range of the purchased radio call declared by the manufacturer in the passport is 50 m. However, in practice this distance is much less, even if the transmitter and receiver are mounted in line of sight, without any obstacles between them. As a rule, this indicator should be divided by three. With an increase in the declared range of radio calls, their retail price also increases. For example, a wireless call with a working radius of 100 m (in reality 35 m) already costs more than 1100 rubles. But you don’t need to buy such ones - after all, the radio amateur, in fact, doesn’t care which call to improve, developing its range. Therefore, consider the simplest - "budget" option. The first step is to remove the cover of the radio housing, because we will increase the range on it. We will not touch its antenna, since at a radio signal frequency of 433 MHz its length practically does not affect the increase in the distance of the transmitter-receiver link. The photo shows radio receivers with the cover removed - two models that differ in appearance. But they have the same circuit (shown on p. 21), although the execution on the printed circuit board is different, in particular, one of the photos shows a variant assembled from discrete elements, and the other one - from elements in SMD packages for surface mounting. Pin 2 of U1 is active high when a radio signal is received from the receiver (when a button is pressed on it). Conclusions 1 and 8 U1 - vice versa: a high level - at rest, and a low logic level - when a control signal is received. These two signals can be used to control load devices with a simple add-on. In order for the remote device to turn on the pump to work effectively (the first time you press the transmitter button, it connects the pump to the 220 V network, and when you press it again, it turns it off), you will need to assemble a simple additional device and connect it to the finished circuit (board) of the industrial wireless call receiver . Receiving Node Improvement The diagram (below) shows the electrical circuit of the set-top box (additional device) of the wireless call receiver. In parallel with the EL1 incandescent lamp, a submersible pump is connected (not shown in the diagram) with a corresponding reinforced hose stretching to the house from the well. The EL1 lamp is an additional light indicator of the pump operation, thanks to it you can make sure at a distance that the command from the transmitter has been received, the remote device has worked, and the pump has turned on. The output of the set-top box is connected to the base printed circuit board of the radio call receiver with unshielded wires of the MGTF-0,4 type (or similar), while the common wire is connected (to the power minus) and output 3 of the DD1.1 (K561TM2) microcircuit element to output 2 of the CD4069BD microcircuit (in some D4069UBC models). Domestic analogues of these microcircuits are KR1561LN4 and K561LN5. When a radio signal is received from the transmitter (its duration is about 2 s provided by the key fob transmitter, regardless of the duration of exposure to its button), at pin 2 of the CD4069BD (U1) microcircuit, the signal level changes from low to high. Conclusions 6 and 7 of the U2 chip, which is a melodies generator, are connected to a low-power dynamic head. Thus, in order to prevent a melodious call from turning on during the signal transmission over the radio channel, it is enough to break the printed conductor from terminal 7 U2 to the dynamic capsule. Or unsolder one of the conductors leading to it.
The basis of the console is a trigger on one element of the popular K561TM2 chip. Without going into the details of its work (many articles have been written about this), I will note the main thing: this microcircuit has two D-flip-flops containing two asynchronous control inputs S and R. The trigger switches on a positive differential at clock input C (pin 3 DD1.1 ). In this case, the logic level present at the input D is transmitted to the direct output Q. When the logic level is high at the reset input R, the flip-flop is reset. The supply voltage can be in the range of 5 ... 9 V (about the experiment to increase the supply voltage of the receiving node - below). Now, knowing the operation of the DD1.1 chip, you can understand the general principle of the set-top box. When the power is turned on, the input R DD1.1 at the first moment, thanks to the discharged capacitor C2, receives a high logic level, which resets the trigger - a low voltage level is set at the direct output Q. Transistor \/T1 is closed, relay K1 is de-energized, lamp EL1 is off, the pump is not working. After about a third of a second (this is due to the capacitance of the oxide capacitor C2 and the resistance of the resistor R1), the first one will charge almost to the supply voltage, and the level at the input R (pin 4 DD1.1) will change to low. Now the trigger is ready to receive signals on the clock input C, which, as follows from the diagram, has a low initial level. When the radio signal from the transmitter from the receiving device enters the input C of the DD1.1 chip, a high voltage level is supplied from the remote call circuit. As a result, the flip-flop is transferred to another stable state - now its direct output Q has a high voltage level. Transistor VT1 turns on relay K1, and its contacts, in turn, close the electrical circuit for powering the lighting lamp EL1 and the submersible pump. The trigger stays in this state for an arbitrarily long time, until the next positive edge of the pulse at input C, upon receipt of which (the next keystroke on the transmitter remote control) the trigger goes into its initial state - the EL1 lighting lamp goes out, the pump is de-energized and turns off. The C2R1 circuit resets the trigger of the DD1 chip to its original standby mode when the power is turned on. Oxide capacitor C1 performs the function of a filter element for power. Diode VD1 prevents reverse voltage surges when the relay is turned on / off. The total power of the switched load depends on the parameters of the electromagnetic relay K1 and in our case is limited to 350 watts. Since the number of discrete elements of the set-top box is small, they are all mounted on a 30x40 mm section of a perforated board and, together with the connecting wires, are placed in the standard housing of the remote call receiver in the battery compartment. To reduce the effect of electrical interference, it is desirable that the wires connecting the device to the power source and coming from relay K1 to the pump have a cross section of at least 1,5 mm and a minimum length. About details Fixed resistors MLT-0,25 (MF-25). Oxide capacitors of the K50-26 type for an operating voltage of at least 16 V. The rest are non-polar capacitors of the KM-6B type. The DD1 (K561TM2) microcircuit can be replaced by the K561TM1 without compromising the efficiency of the node, but in this case the circuit will have to be changed, since the conclusions of these microcircuits have different purposes. Detailed information about this replacement option can be found in reference books on modern CMOS chips. Transistor VT1 - field, with a large input resistance. This minimizes the leakage current in the radio standby state and has little to no effect on the flip-flop output despite the low R2 terminating resistor. Relay K1 can be replaced by RES43 (version RS4.569.201) or another, designed for a response voltage of 4 ... 4,5 V and a current of 10 ... 50 mA. It is undesirable to install a relay with a switching current of more than 100 mA in the device, since the VT1 transistor that controls the operation of the relay has a power limit.
Instead of KP540A, you can use a field effect transistor of any of the KP540 series or its foreign counterparts BUZ11, IRF510, IRF521. LED НL1 - any, with its help it is convenient to control the operation of the relay and the closure of the executive contacts. If necessary, the elements NI and (R3) can be excluded from the circuit without consequences. An additional (in manual mode) pump switch in the diagram is shown under the designation SA1. Coil L1 - frameless with a diameter of 4 mm from 1,5 turns of silver-plated wire with a diameter of 0,8 mm (turn to turn). Inductor L2, type D-06 with an inductance of 82 μH (micro Henry). In the basic version, an autonomous power supply is provided - 2 finger cells of 1,5 V each. But in the conditions of the recommended use of a remote call device, it is best to supply stationary power from a stabilized power source with a voltage of 5 V with deviations not exceeding ± 5%. Such a source can be, for example, a stabilizer on a KR142EN5A chip. Current consumption of the transmitter in active mode - 35 mA. The current consumption from the power source of the receiving node in the constant standby mode does not exceed 10 mA and increases to 50 mA when the relay indicated in the diagram is turned on. With other types of relays, the current consumption may have a different value. Attention, important! The optimal receiver supply voltage is 5-9 V. It is not worth increasing the supply voltage of the receiving node, since the range of the device does not increase from this innovation (tested experimentally by bringing the voltage to 12 V). The transmitter itself, outwardly representing a case in the form of a key fob, the size of a standard matchbox, does not need to be finalized. In order not to change the battery once a year (the same as that installed in most burglar alarm transmitters for cars - 12 V, 23AE, manufacturer GP Ultra or similar), the transmitter is powered using any industrial adapter with a stabilized output voltage 12 V and a current of at least 0,5 A, for example, type TV-182-S. Tuning coil L1 with an armored core inside. External coil diameter 4 mm, winding 5 turns of silver-plated wire with a diameter of 0,8 mm. L2 - choke type D-06 with an inductance of 82 kH. The transmitter antenna is worthy of a detailed description. To increase the operating range, a telescopic whip antenna for radio receivers (available in stores) is soldered to the antenna contact on the printed circuit board using a piece of wire MGTF-0,8 (or similar). Or, in extreme cases - which is incommensurably worse - use as an antenna a stranded wire similar to the regular one 350 ... 400 mm long, fluffing thin conductors at its end, like flower petals (diameter of the "flower" - 60 ... 80 mm ). The greatest range of work with a telescopic antenna (in practice) will be when the "telescope" is extended to the middle, that is, by the same 350 ... 400 mm. Now, subject to the recommended modification of the antenna in the transmitter device, it is possible to obtain a range of up to 200 m in direct line of sight and remotely control an electric pump or other active load, the choice of which is limited by the parameters of the executive relay and the author's imagination. Author: A.Kashkarov
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Comments on the article: Paul You have added a trigger circuit to the receiver circuit. It is not clear to me due to what the range of radio communication is increased? How to find a wireless bell with the same receiver circuit or a similar circuit? And as I understand it, no changes are made to the transmitter circuit, which means it should also be similar to yours?
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