|
Arabic
Bengali
Chinese
English
French
German
Hebrew
Hindi
Italian
Japanese
Korean
Malay
Polish
Portuguese
Spanish
Turkish
Ukrainian
Vietnamese|
ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING We control by radio - transmitter and receiver. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Beginner radio amateur TRANSMITTER operates at a frequency of 28.2 MHz, the modulation frequency is approximately 2 kHz. Its schematic diagram is shown in Figure 1.
The high frequency generator is assembled on the transistor T1, according to the capacitive three-point circuit. Its frequency is determined by the circuit R2, C2, C4, C5. The ratio of the capacitances of capacitors C4 and C5 determines the amount of feedback. Communication with the antenna is made according to the P-loop scheme. This made it possible to simplify the design of the transmitter and facilitate its adjustment. The value of this connection depends on the ratio of the capacitance of the capacitor C2 and the capacitors C4 and C5 connected in series. Capacitor C1 is installed in order to avoid disruption of the generator oscillations when the antenna is closed to the transmitter housing. The transmitter modulator is assembled according to the multivibrator circuit on transistors T2 and T3. The Kn1 button serves as a control that allows you to turn on and off the executive engine on the model. Do not use the power switch for this purpose! And that's why. The electric motors installed on the model are a source of rather strong radio interference, especially considering their close location to the receiver. And the receiver is made in such a way that its sensitivity to interference decreases during the operation of the transmitter. Therefore, commands are given by turning the modulation on or off. The transmitter is located in a duralumin case measuring 110x45x150 mm. All parts of the transmitter, except for the controls, batteries and antenna, are placed on a circuit board made of 1,5 mm thick getinaks. Board dimensions 90x50 mm. For mounting, the board is drawn with a caliper into squares with a side of 5 mm. Holes with a diameter of 1 mm are drilled at the intersections of the obtained lines for fastening parts. Their placement on the circuit board and the connections to each other are shown in Figure 2. The dotted lines here indicate the connections made from the underside of the board. Holes with a diameter of 4 mm, drilled in the corners, serve to fix the board in the transmitter housing.
The L1 loop coil is wound on a plastic frame with a diameter of 9 mm with a PEV-2 wire with a diameter of 0,51 mm. The frame and core can be used from the contours of the Rubin TV. Inductor Dr1 has an inductance of approximately 8 μH. You can use the correction choke from the TV or make it yourself. To do this, on the MLT-0,5 resistor, the resistance of which is at least 100 kOhm, wind 90 turns of PEV-2 wire with a diameter of 0,1-0,12 mm. Capacitors C1-C5 must be ceramic, and C6 and C7 can be paper. The circuit board is designed for MLT-0,5 resistors. But resistors MLT-0,125, ULM, VS-0,12 and others can also be used. Transistor T1 can be of type P403, P4I4-P416, GT308 with a gain of at least 50. But in place of T2 and T3, low-frequency transistors P13-P16, MP39-MP42 also work fine, but at the same time, their gain should also not be less than 50. The transmitter is powered by two 3336L batteries connected in series. If you want to reduce the size of the transmitter, then use the Krona batteries. The transmitter antenna has a length of approximately 80 cm and is screwed from two dural rods with a diameter of 4 mm using a tube with an internal thread. A telescopic antenna from a transistor receiver is well suited for the transmitter. When placing the circuit board in the housing, make sure that the L1 coil is at least 8 mm away from the housing. Properly assembled from serviceable parts, the transmitter immediately starts working. It is only necessary to check the frequency of the transmitter and, if necessary, adjust it with the core of the coil L1. RECEIVER (See Fig. 3). It is assembled entirely on transistors. Even at the output of the receiver there is no traditional relay - a powerful transistor has taken its place. This made it possible not only to exclude a rather scarce part, but also to increase the reliability of the receiver.
Its first cascade is assembled according to the self-extinguishing super-regenerator circuit, and the high-frequency part of this cascade is assembled according to the inductive three-point circuit. Chain R3, C5 determines the blanking frequency. In our receiver, it is approximately 100 kHz. A high quenching frequency reduces the gain of the cascade, but it makes it possible to separate the useful signal from the quenching frequency using fairly simple filters. The operating mode of the cascade is set by potentiometer R2. The single-stage low-frequency amplifier of the receiver is assembled on a transistor T2. The signal to the input of the cascade is fed through the filter R4, Sat. Thanks to the inclusion of capacitor C6 in the feedback circuit, its capacitance was significantly reduced. From the output of the ULF through the resistor R7, the signal is fed to the input of the second detector, assembled on the transistor T3. This made it possible to increase the input impedance of the cascade. The constant component of the detected signal, supplied to the output transistor T5 through the emitter follower T4, controls the operation of the executive motor ED-1. In order to increase the reliability of the circuit, the receiver and motor are powered by separate batteries. The only homemade part of the receiver is the L1 coil. It is wound on a plastic frame with a diameter of 8 mm and contains nine turns of PEV-2 wire with a diameter of 0,51 mm. The winding is made turn to turn, and the tap is made from the third turn. The reading is taken from the end of the coil that is connected to the negative power wire. This is done as follows: first, 3,5 turns are wound on the frame and the place where the tap should be made is marked. Then carefully clean the upper surface of the wire with a sharp knife. A tinned wire with a diameter of 0,2-0,3 mm is soldered to the cleaned place. After winding the coil, the wiring is connected to the appropriate terminal. The rest of the receiver parts are standard. Transistor T1 can be of type P403, P414-P416, and T2-T4 - MP20B. The gain of the transistors must be at least 100. As the output transistor T5, transistors P213-P217 with a gain of at least 25 can be used. Capacitors, other than electrolytic, are ceramic. Capacitors C1 and C7 can be increased to 33 nF, and capacitor C8, on the contrary, reduced to 0,5 uF. An increase in the capacitance of the capacitor C9 leads to an increase in the acceleration and stop time of the engine. All fixed resistors are of the MLT-0,5 type, but MLT-0,125, VS-0,12 can also be used. Trimmer resistor R2 type SP-3. Structurally, the receiver is mounted on a getinax board 50x120x1,5 mm in size. Preparing the receiver board for mounting is done in the same way as the transmitter board. Its wiring diagram is shown in Figure 4.
The tuning of the radio receiver must be carried out with the antenna connected. It is best with the tone with which it will work on the model. An oscilloscope is connected to the emitter of transistor T1 through a resistor of 20-30 kOhm. By turning the knob of the potentiometer R2, the most stable damping frequency amplitude is obtained. Then, a signal with a frequency of 28,2 MHz, modulated in amplitude with a frequency of 1000 Hz, is fed from the signal generator to the input of the receiver. The connection between the generator and the receiver should be as weak as possible. You can, for example, place the wire coming from the generator at a distance of 1-2 cm from the receiver antenna. By rotating the core L1, they achieve the maximum value of the useful signal. It will be viewed as a change in the amplitude of the blanking signal. The remaining stages of the receiver do not require tuning. If it is necessary to increase the current strength to rotate the ED-1 electric motor, replace the T5 transistor. The maximum value of the output current is 0,8-1A. Author: E.Tarasov
Traffic noise delays the growth of chicks
06.05.2024 Wireless speaker Samsung Music Frame HW-LS60D
06.05.2024 A New Way to Control and Manipulate Optical Signals
05.05.2024
▪ Single layer sensor recognizes multiple simultaneous touches ▪ Safe genetically modified mosquitoes ▪ The implant will return a person to tactile sensations
▪ section of the Electrician website. PUE. Article selection ▪ article Do not speak with longing: they are not, but with gratitude: they were. Popular expression ▪ Article Fennel ordinary. Legends, cultivation, methods of application ▪ article Wiper control unit. Encyclopedia of radio electronics and electrical engineering
Home page | Library | Articles | Website map | Site Reviews
www.diagram.com.ua |
See other articles Section 
Latest news of science and technology, new electronics:
All languages of this page