Single-channel remote control switch - power supply circuit - circuit diagram - Huaqiang Electronic Network

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The remote control switch described in this paper has a remote control distance (greater than 30 meters), no direction limitation, can penetrate the wall, work stably, and has a small size. As long as such a circuit is added to the power supply circuit of the household electrical appliance, the home appliance can have a remote control function. The following describes its circuit principle and production.

First, the circuit principle: 1. Remote control: circuit as shown in Figure 1, a multi-vibrator consisting of T5, T6, etc., generated square wave signal, for the 240MH--260MH RF generated by the inductor three-point oscillator composed of T7 Pulse modulated, the modulated RF signal is radiated from the printed antenna of the board to the space. The battery used in the remote control is an A23 type 12V battery, which can be used for half a year and is easy to replace. 2. Receiving circuit: The circuit is shown in Fig. 2. The UHF receiving demodulation circuit is composed of T1, L1, C0, etc. Adjusting C0 can correct the receiving circuit and the remote controller in the optimal position. The demodulated pulse signal is sent to the operational amplifier A1A through R5 and C5 for comparison and amplification. The output signal is sent to the operational amplifier A1B for peak comparison after passing through the C7, D2, and D3 voltage doubler circuits. When the 6-pin inverting terminal has a peak pulse exceeding the threshold voltage set by the 5 pin, the 7 pin outputs a hopping low level signal, triggering the bistable circuit composed of T2, T3, etc. to reverse, and controlling the T4 to conduct. Or cut off, the relay is pulled or released. The integral delay function of R11 and C8 can effectively suppress and eliminate the interference of various short-time sharp pulses on the circuit (such as lightning, fluorescent light, etc.).

Second, production and debugging: 1, the remote control circuit is simple and generally can work without debugging, need to pay attention to the selection of the launch tube T7 and inductance. The magnification of T7 can be around 80. 2. The receiving circuit components are selected according to the parameters in the figure. The amplification factor of T1 is about 90, and the relay is a micro relay of 12V. Other components have no special requirements. 3. Press the remote control switch when debugging, connect the negative electrode to the A1A output pin of the op amp with a high-impedance earphone, and then turn the C0 with a non-inductive screwdriver until the “beep” sound in the earphone is maximum. After the commissioning is completed, the transmitter and receiver are respectively installed in a suitable casing. When in use, it will receive the normally open contact of the circuit relay, connect it in the power supply circuit of the appliance to be controlled, then press the remote control, the relay will pull in, the appliance works, press the remote control relay again, and the appliance is powered off.