The radio remote control circuit is to utilize the radio signal as a remote instruction to complete various designated actions, prescribed. The amateur frequency band has 28.0 ~ 29.7MHz, 50 ~ 54MHz, 1448 MHz and 420 ~ 448MHz, etc., the higher frequency, the requirements of the device are higher, this paper first introduces radio remote control composed of discrete components within 28.0-9.7MHz. Unit circuitry.
The radio remote control circuit consists of two parts: the radio transmitter and the receiver. The transmitter can be divided into no modulation, modulation, frequency modulation and phase modulation, etc., the receiver can be divided into the receiver. Directly amplify, super reproducible and over-extra differentials. This article describes the unmatched and modulated radio remote transmitter and then describes the unit circuit of the radio remote receiver.
Radio remote transmitter
Figure 1 is a simplest three-point radio remote transmitter, and the oscillation frequency is determined by L2 and C2, and L1, L2 is wound around the same φ8 magnetic core, and L2 winds 10, in the second turns The Vt collector, L1 is 5 turns. The circuit is a non-modulated, pressing the button SB, the circuit is, and the antenna radiates high frequency carrier to the air. The circuit transmits only a few tens of millions of millions, and the remote control range is several tens of meters. VT is a super high frequency tube with a cutoff frequency of 200 MHz. Such as 9018, 3DG12, etc.
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Figure 1 The simplest three-point radio remote transmitter
2 is a three-point oscillator that is grounded by the base ground, with a radio remote transmitter, the circuit operation is stable, the oscillation frequency can be done, but the output power of the circuit is slightly smaller, L2 and L3 are high frequency choke coils, available Φ0.1 Paint Bread line The resistance of the resistance of 1 MΩ or more, and then the two-wire soldering can be sold on the resistor two-pin feet, and the purpose of setting the high frequency choke coil can effectively reduce the human hand according to the switch SB. The human body induction, the circuit is also a non-modulated.
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Figure 2 Capacitor three-point oscillator of the base ground
Figure 3 is a push-pull radio remote transmitter having a large output power. The output power can reach several tens to hundreds of milliwatts. The remote distance can reach hundreds to a thousand kilometers, and it is also no modulation, directly utilizing high frequency carriers. As the remote control, in order to make the circuit work well, the characteristics of the VT1 and VT2 two tubes are as consistent as possible. L2 can be wrapped around 6, the coil diameter is 12 ~ 15mm, and the bone rack is used, the center tap to the power supply, the two ends of the coil are directly soldered on the two soldering sheets of the ceramic micro-adjustable capacitor C2, and L1 uses the same line to bypass 2 The room is between L2.
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Figure 3 Push-pull radio remote transmitter having a large output power
Figure 4 is a non-modulated radio remote transmitter using quartz crystal, the circuit characteristics is easy to activate, the frequency stability is high, the structure is simple, and B uses a quartz crystal encapsulated by a 28.750 MHz aluminum shell, and the transmitting of each circuit is transmitted. The antenna can be used with a lens antenna for the transistor radio, and the length is between 0.6 to 1.5 m, and the antenna having a different length has a slight effect on the emission distance, and the optimum length is 1/4 of the high frequency carrier wavelength.
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