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The sound controls the model. Tips for a modeller


Directory / Radio control equipment

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You've obviously had to read about beep-driven models. The receiving device, the description of which we bring to the attention of readers, responds to a sound signal of a certain strength. Its source can be, for example, a whistle, a pipe or a special transmitter of sound commands. Equipped with such equipment, the model executes commands in any sequence: "forward", "backward", "left", "right". The termination of the sound signal or its decrease to a certain level causes the model to stop ("stop"). Here is how the device works.

The model has four alternately flashing lamps, each of them corresponds to a specific command. If during the period during which one of the lamps is on, a continuous sound signal of sufficient strength is given, the model will execute the intended command. But as soon as the receiver stops "hearing" the sound, the model stops, and the command lamps continue to flash alternately.

To control such a device, certain skills are needed. Therefore, the burning time of each lamp is first set to 2 s, and then gradually reduced, bringing it to 0,5 s or even less.

The receiver is powered by two 3336L batteries connected in series.

On the A1 chip (Fig. 1), a low-frequency amplifier is assembled, and on the elements D1.1 and D1.2 of the IC D1, a reset pulse shaper, which, when the toggle switch S1 is turned on, sets the pulse counter D2 to the initial state. A clock generator is assembled on elements D1.3 and D1.4, and a decoder is assembled on elements D3.1 - D3.4 of the D3 chip. The pulse counter and the decoder make up the pulse distributor. It has one input (pin 3 D2.2) and four outputs (pins 3, 6, 8 and 11 D3). The task of the distributor is to convert the input pulse sequence into an output one. A pulse recorder is assembled on the D4 chip. The role of electronic keys is performed by transistors V1-V5. A voltage regulator is assembled on a V8 semiconductor triode.

Sound controls the model
Rice. 1. Schematic diagram of an audio receiver

Consider the operation of the device in standby mode (or no sound signal). Immediately after turning on S1, the clock generator begins to generate pulses at a frequency of 1 Hz. The first pulse received at the input of the distributor causes a logic zero to appear at the output of element D3.2 (pin 6) (logic 0 level corresponds to a voltage of 0,05 V, logic 1-3,6 V): transistor V3 opens and lamp H2 flashes. When the second pulse arrives at the distributor input, only transistor V4 opens and lamp H3 lights up. The third pulse will turn on the V5 transistor, and with it the H4 lamp. The fourth pulse will open only the transistor V2 - the lamp H1 is on. The fifth pulse opens transistor V3 again, as evidenced by the lit lamp H2. And so, in turn, all the lamps will continue to flash, and the model will remain motionless until it receives a sound signal "Let's say that it comes in the interval between the H1 lamp lighting up and going out (the "forward" command").

From the dynamic head B1, electrical oscillations through the transformer T1 and the capacitor C3 are fed to the input of the A1 microcircuit. The signal amplified by it through the capacitor C6 comes to the pulse recorder, and a logical 8 appears at its output (pin 4.4 of element D0). Transistor V1 will open and relay K1 will work. Its contact plates K1.1, K1.2 break the power circuit of the lamps H1 - H4 and turn off the clock generator. At the same time, relay K2 is activated, while the lamp H1 is on, transistor V2 is open. Its contact system K2.1 and K2.2 (Fig. 2) connects the electric motors M1, M2 to the power source: the model will move forward as long as the sound signal is active. But as soon as it becomes less than 3 mV, a logical 1 appears at the output of the pulse recorder - transistor V1 closes, relay K1 turns off and the clock generator continues to work. As a result, the relay K2 and the electric motors M1, M2 will be de-energized, and the lamps H1 - H4 will start flashing in sequence. In the same way, the model will execute the “backward” command if the sound signal arrives during the burning of the H3 lamp, the “left” or “right” commands - during the burning of the H4 or H2 lamps, respectively.

Sound controls the model
Rice. 2. Electrical diagram of the running gear of the model

Sound controls the model
Rice. 3. The location of the elements of the receiver on the circuit board

To control the model, it is not recommended to use frequencies below 400 Hz, since the noise of operating electric motors and gearboxes occupy a band of 25-350 Hz. The use of sound waves above 18 kHz is limited by the frequency properties of the dynamic driver.

The following parts are used in the sound receiver. Dynamic head V1 0,25GD-10 or any other with a voice coil DC resistance of 6-10 ohms. T1 - output transformer from the pocket radio "Malchish" or "Youth". The core is Ш3Х8 mm, the primary winding has 100 turns of PEV-1 0,2 wire, the secondary winding has 900 turns of PEV-1 0,1. Electrolytic capacitors - K50-6, K50-3 or IT, the rest - KLS. Fixed resistors - MLT-0,125 or ULM, R1 - variable resistor SDR-1.

Diodes D311A can be replaced with D311, KD503 with any letter index; microcircuits K155LAZ (former designation K1LB553) - pa K1LBE13, K1LBZZZ; K155TM2 (former designation K1TK552) - on K1TK332. Instead of MP26A transistors, MP20-MP21, MP25-MP26 are suitable, instead of KT315G - KT315 with any letter indices. The static current transfer coefficient for all semiconductor triodes is at least 30. Relays: K2, K4 RES9 (passport RS4.524.202 or PC4.524.215), K1, K3, K5 RES-15 (passport RS4.591.003) with a response voltage of 6-7 IN.

Lamps type MH2,5X0,15. Switch - P2K-1-1. Electric motor - from an electrified toy or DIT-2. Spark arresting coils have an inductance of 15 μH each. On a 600NN ferrite core with a length of 12 and Ø 2,5 mm (from the IF circuits of the Selga, Sokol radio receivers), 25 turns of wire PEV-2 0,35 are wound,

To be sure that the relays are working properly, they need to be checked. To do this, the winding of the relay under test is connected to a 7 V voltage source and the tester measures the resistance between the closed plates. If it is equal to zero, such a relay is suitable for operation. When the contact resistance is greater than zero, remove the protective cover and clean the contact surfaces.

Connect an audio frequency generator to the negative terminal of capacitor C3, setting the output voltage to 3 mV, frequency 1000 Hz. At the time of ULF tuning, unsolder the negative terminal of capacitor C6, connect a millivoltmeter to it, setting the measurement limit to 10 V. Selecting the value of resistor R3, achieve millivoltmeter readings of 2,5-3 V. Then temporarily replace resistor R6 with a variable value of 4,7 kOhm and connect the tester to conclusion 8D4.4. Using a variable resistor, set the tester needle to 0,03 - 0,1 V. In this case, relay K1 should work.

If you now turn off the sound generator, K1 will return to its original state, and at pin 8 of element D4.4, the voltage will increase to a value of 1,8 - 3 V. Replace the variable resistor with a constant one, use R1 to set the desired lamp flash frequency and check the operation of the entire device 8 overall.

With lamps of type MH1X0.068, increase the resistance R7 - R10 to 47 ohms.

The sound receiver is suitable for any moving model driven by electric motors. Lamps are placed on it in any place at the choice of the designer, but in such a way that they constantly remain in the field of view of the modeller.

The dynamic head can be installed above the electric motors with the diffuser up and covered with a plastic spherical cap, in which 20-25 holes Ø 2,5-3 mm are made.

Author: A.Proskurin

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