200m four-button remote control module design

This is a 200-meter four-button remote control module that is currently widely used. It is often used for alarm defense, garage door remote control, motorcycle and car anti-theft alarm, etc. This type of use requires the remote control distance of the remote control to be not far, generally 50 meters is enough, but the requirements are: the remote control module is cheap, the transmitter handle is small and exquisite in appearance, power consumption is as low as possible, and the operation is stable and reliable.

The transmitter provided here is very small, with a volume of only 58x38x8 mm, using a high-quality plastic shell with mahogany pattern, with a safety cover to prevent accidental touch of the buttons, the antenna is 13 cm long when pulled out, and the remote control is only 20 grams.

Dimensions: 58x38.5x13 mm
Transmitting power: 20 mW
Working current: 14 mA
Working voltage: 12V, A27 alarm dedicated battery
20 yuan each

This is a new 200-meter remote control, 22 yuan each. You can specify "200 meters, white" when purchasing.

The above picture shows the appearance of the transmitter. There are four control buttons A, B, C, and D on the panel and a transmission indicator light. The transmitter uses imported SAW resonators for frequency stabilization, with very good frequency consistency and extremely high stability. The operating frequency of 315MHZ has a frequency stability better than 10-5. There is no need to adjust the frequency during use. It is particularly suitable for use in radio remote control systems such as multiple transmitters and one receiver. However, some low-priced radio remote control modules on the market generally still use LC oscillators, which have poor stability and consistency. Even if high-quality fine-tuning capacitors are used, it is difficult to ensure that the debugged frequency will not shift after temperature changes or vibrations, resulting in a shortened transmission distance.



This is the equivalent circuit diagram of the transmitter

The receiving module can be divided into superheterodyne receiving board and super regenerative receiving board according to the working mode. The super regenerative receiving board is divided into pin-type output and pad-type output according to the different PCB layouts. These three boards are compatible and interchangeable in function. The pin-type receiving board can be easily installed on the required motherboard. The rectangular receiving board and the motherboard are welded vertically. The receiving board is recommended to be placed on the edge of the motherboard and as far away from large metal objects as possible. The square receiving board and the motherboard are welded horizontally. Customers can choose the most suitable receiving board according to actual needs.

Super-regenerative receivers are widely used due to their simple circuits and low costs, while superheterodyne receivers are more expensive, have strong temperature adaptability, higher receiving sensitivity, stable and reliable operation, strong anti-interference ability, good product consistency, low receiver local oscillator radiation, no secondary radiation, good performance indicators, and are easy to pass FCC or CE and other standard inspections, meeting industrial use specifications.

The performance difference and pin function distribution of remote control receiving modules:

Receiver board A Super regenerative pin-type rectangular receiver board: Volume: 48x20x8 mm (15 yuan each)

This is the equivalent circuit diagram of the super regenerative receiver

The super regenerative receiving module has seven leads, namely 10, 11, 12, 13, GND, 17, and VCC, where VCC is the 5V power supply terminal, GND is the ground terminal, 17 is the decoding effective output terminal, 10, 11, 12, and 13 are the 10-13 pins of the decoding chip PT2272 (SC2272) integrated circuit, which are four-bit data latch output terminals. When there is a signal, it can output a high level of about 5V, with a driving current of about 2mA, which corresponds to the four buttons on the transmitter one by one.

The receiving module is manufactured using SMD patch technology. It is a super-regenerative receiving method. It contains amplification shaping and decoding circuits and is extremely convenient to use.
1. There is a frequency selection circuit at the antenna input end, which does not rely on the frequency selection function of the 1/4 wavelength antenna. When the control distance is close, the external antenna can be shortened or even removed
. 2. The radiation of the receiving circuit itself is extremely small, and the shielding effect of the mesh grounding copper foil on the back of the circuit module can reduce the leakage of its own oscillation and the intrusion of external interference signals.
3. The receiver uses a high-precision copper core inductor with a skeleton to adjust the frequency to 315M and then seal it. Compared with the circuit that uses an adjustable capacitor to adjust the receiving frequency, the temperature, humidity stability and mechanical vibration resistance are greatly improved. The adjustable capacitor has a low adjustment accuracy and only has an adjustment range of 3/4 turns, while the adjustable inductor can be adjusted in multiple turns. The adjustable capacitor cannot be sealed after adjustment, because whether it is a conductor or an insulator, the proximity or intrusion of various media will change the capacitance of the capacitor, thereby affecting the receiving frequency. In addition, when an unsealed adjustable capacitor is vibrated, displacement will occur between the stator and the rotor; when the temperature changes, thermal expansion and contraction will cause the distance between the stator and the rotor to change; humidity changes will change the capacity due to changes in the medium; long-term work in a humid environment will also change the capacity due to oxidation of the stator and the rotor. These will seriously affect the stability of the receiving frequency. The use of adjustable inductors can solve these problems, because the inductor can be sealed after adjustment, and the insulator sealing agent will not change the inductance. In addition, due to the use of patch technology, there is no need to worry about the receiving frequency drift even if there is a strong vibration. The receiving bandwidth of the receiving circuit is about 500KHz, and the center frequency of the product has been adjusted to 315MHz when it leaves the factory. The fine-tuning inductor on the receiving chip has an adjustable frequency range of about 5MHz. Do not change it easily during use to avoid affecting the performance.

Receiver board B superheterodyne pin type receiver board: 41x24x6 mm (25 yuan each)

The superheterodyne receiver board provided here uses imported high-performance wireless remote control and data transmission dedicated integrated circuit RX3310A, and uses a 316.8MHZ SAW resonator, so it works stably and reliably and is suitable for all-weather work in relatively harsh environments.

The ANT on the left side of the superheterodyne receiving board is the antenna terminal, and the GND next to it is the antenna ground terminal. It is best to connect an antenna with a characteristic impedance of 50 ohms. You can also use a 30 cm long wire directly connected to the ANT terminal instead of the antenna.

RX3310A integrated circuit introduction:

RX3310A is a Taiwan HMARK company specializing in amplitude keying ASK modulation wireless remote control and data transmission signal receiving integrated circuit, contains low noise high frequency amplifier, mixer, local oscillation, intermediate frequency amplifier, intermediate frequency filter, comparator, etc., for a single frequency conversion superheterodyne circuit, dual row 18-pin wide body SMD package, the main technical indicators are as follows:

operating frequency: 150 ~ 450MHZ
operating voltage: 2.7 ~ 6V
operating current: 2.6 mA (3V power supply)
receiving sensitivity: -105DBM (1K data rate and antenna matching)
maximum data rate: 9.6KBPS

superheterodyne receiving chip RX3310A use development information

The signal received from the external antenna is coupled to the frequency selection network composed of L2 and C11 through C10 for impedance transformation and then input to the 14th pin of the internal high-frequency amplifier input of RX3310. After high-frequency amplification in the chip (gain is 15-20DB), the signal is mixed with the local oscillation signal (316.8M) by the mixer to generate a 1.8M intermediate frequency signal. This intermediate frequency signal is output from the 3rd pin after internal intermediate frequency amplification, and then enters the comparator for amplification and shaping, and finally the data is output from the 8th pin.

The superheterodyne receiver has high requirements for antenna impedance matching. The impedance of the external antenna must be 50 ohms, otherwise it will have a great impact on the receiving sensitivity. Therefore, if a 1/4 wavelength ordinary wire is used, it should be 23 cm for the best. The lead length from the antenna root to the antenna welding point of the transmitting module should be reduced as much as possible. If it cannot be reduced, it can be connected with a RF coaxial cable with a characteristic impedance of 50 ohms (there is a special grounding solder joint on the right side of the antenna solder joint)

Usually the sensitivity of super regenerative receiver is about -106DBM, with many components, poor stability and complex processing, while the sensitivity of super heterodyne receiver using RX3310A can reach -102DBM, with few peripheral components and high integration, which is suitable for large-scale production. There are two types of super heterodyne receivers: acoustic frequency stabilization and LC frequency stabilization. The sensitivity of LC frequency stabilization can reach -104DBM, but the stability is slightly poor, while the sensitivity of acoustic frequency stabilization is about -102DBM, with good stability. The super heterodyne receivers provided here are all acoustic frequency stabilization.

Application Examples

There are four buttons on the transmitter handle. When the buttons on the transmitter are pressed, the transmitting circuit will be activated and enter the transmitting state. The transmitter does not consume power when it is static. The battery installed in the machine is only used for point transmitting state. When used for alarm setting and electrical switch, each battery can generally be used for more than one year. The battery capacity is 45mAH.

In order to test whether the remote control module works properly, we can add a 5-6 volt DC voltage to the VCC and GND terminals of the receiving module, or we can use the 78L05 three-terminal voltage regulator chip to obtain a 5 volt regulated working power supply. Connect a light-emitting diode to the ground at terminals 10, 11, 12, 13, and 17 (the negative electrode of the light-emitting diode is grounded). The receivers of the remote control modules provided here are all latching types, that is, they can maintain the instantaneous state of the remote control signal. Suppose we press the A button of the transmitter, the corresponding LED of channel 11 can light up, release the A button of the transmitter, and the LED of channel 11 is still lit in a self-holding state (latched), until other buttons such as B are pressed, 11 goes out and the LED at 12 lights up. Terminal 17 is the effective output terminal of decoding. No matter which button of the transmitter is pressed, as long as the decoding is successful, terminal 17 becomes a high level until the transmitter stops transmitting. We can use terminal 17 in conjunction with 10, 11, 12, and 13 to make the remote control module have a non-latching function, as shown in the following production example 2.

Receiver board C-L4 multi-purpose single relay remote control receiver board (receiver board 25 yuan each)

This is our newly developed multi-purpose single relay remote control receiver board, which can be used with the 100m four-button remote control, 200m four-button remote control, 800m four-button remote control, 2000m four-button remote control, 500m emergency button, etc. introduced on the website.

Purpose: Used to remotely control the opening and closing of a circuit, or the turning on and off of a lamp.

This receiving board has a 4-position jumper column, which is used to switch one of the four remote control signals (such as the A button in the remote control buttons A/B/C/D). There is also a 2-position jumper column, which is used to switch between latching and non-latching modes. The so-called latching mode is that when the A button is pressed, the relay of the receiving board is attracted and maintained, and the relay is only released when any of the B/C/D buttons is pressed. The so-called non-latching mode is that when the A button is pressed, the relay of the receiving board is attracted, and if the A button is released, the relay of the receiving board is released immediately.

Netizens with practical experience will find that under the same conditions, the remote control distance of the non-latching receiving board using the M4 chip is much smaller than that of the L4 latching type, sometimes only half of the latching type or even less, and the relay has unstable attraction. This is because in the non-latching state, the remote control signal needs to be synchronized about 30 times per second. When the load controlled by the relay is a motor or other equipment that is prone to interference, the interference generated by the equipment itself after power-on will interrupt the remote control signal, causing the relay to work in a jumping unstable state.

Here we adopt a method, still using the L4 decoding chip, by delaying the signal output from pin 17 for about 0.5 seconds, making the remote control output signal more stable. The stationmaster used this method when developing remote control gate products to make the remote control farther and more stable. Practice has proved that a 0.5-second lag delay will not affect the operation.

Receiver board C-T4 multi-purpose single relay remote control receiver board (receiver board 25 yuan each)

By replacing the chip with a 2272 T4 chip and selecting the latch mode, the receiving board can be operated in the trigger flip mode, that is, press the A button of the remote control once, the relay of the receiving board is energized, and press the A button of the remote control again, the relay of the receiving board is released. Application: Use a 200-meter four-button remote control + 4 trigger flip single relay receiving boards, and the 4 receiving boards are switched to the four channels A/B/C/D respectively. At this time, the A/B/C/D of one remote control can control the receiving boards in four locations respectively, such as multi-channel (4 channels and below) home lamps and electrical appliances control.

Note: The receiving board and the housing will cost an additional 5 yuan, and replacing the receiving head with a 3310 superheterodyne will cost an additional 8 yuan.

Receiver board D Four-relay latch type receiver board: (receiver board 35 yuan each)

Its function is: there are 4 high-current relays on the receiving board, corresponding to the 4 buttons of the transmitter, and the logical relationship of the action is latching mode, that is to say: press a button of the transmitter, such as A, and the corresponding A relay of the receiving board will be energized. Release the button, and the A relay will remain energized until the next time any one of the buttons B, C, and D is pressed, the corresponding relays in B, C, and D are energized, and the A relay is released, that is to say, the receiving board can remember the state of the last remote control, and can self-lock and maintain until the next remote control command is received to change the state of the relay.

Each relay has a corresponding red light-emitting diode to indicate its working state. The two-position terminal on the lower right foot of the circuit board is the 12V DC power input terminal, with "+" on the left and "-" on the right. Each relay has a corresponding three-position terminal, which is a set of normally open to normally closed contacts, with the middle as the common terminal, the left side as normally open, and the right side as normally closed. The PCB surface of the board is detailed.

Receiver board E Four-relay non-latching receiver board: (receiver board 35 yuan each)

Purpose: Used for remote control of some occasions that require inching to achieve four-way remote control, such as remote control of the opening and closing of electric doors, and some occasions controlled by touch switches, such as the volume increase and decrease buttons, channel increase and decrease buttons on household appliances.

The difference between this circuit and the previous receiving board is that the receiving decoding chip uses the PT2272 chip with the M4 suffix, so it can realize the function of four-way inching remote control. For example, when a button on the transmitter is pressed, such as A, the corresponding A relay of the receiving board will be energized, and when the button is released, the A relay will be released synchronously.

Receiver board F Four-relay anti-interference non-latch receiver board: (receiver board 38 yuan each)

Netizens with practical experience will find that under the same conditions, the remote control distance of the non-latching receiving board is much smaller than that of the latching type, sometimes only half of the latching type or even less, and the relay has unstable attraction. This is because in the non-latching state, the remote control signal needs to be synchronized about 30 times per second. When the load controlled by the relay is a motor or other equipment that is prone to interference, the interference generated by the equipment itself after power-on will interrupt the remote control signal, causing the relay to work in a jumping unstable state.

Here we adopt a method that uses the L4 decoding chip. By delaying the signal output from pin 17 for about 0.5 seconds, the remote control output signal is made more stable. Of course, this is achieved at the expense of the real-time performance of the remote control. The stationmaster adopted this method when developing remote control gate products to make the remote control farther and more stable. Practice has proved that a 0.5-second lag delay will not affect the operation.

There are several added components in the upper right corner of the board. Changing the value of the capacitor can change the delay time. When using 22UF, the delay is about 0.5 seconds, 100UF is about 1 second, and 220UF is about 2 seconds.

Receiver board G Transient trigger flip type four relay anti-interference receiver board: (receiver board with shell 48 yuan each)

The four-channel instantaneous trigger flip-type receiver board can control four channels independently without affecting each other. For example: press the A button on the remote control, the relay corresponding to channel A is energized and maintained, press the A button again, the relay is released, and the working process of other channels is the same.

This type of product on the market usually uses the CD4013 integrated circuit to complete the control, but it is prone to the disadvantage of unstable remote control. For example, it may be unstable when used to control loads such as motors and electronic energy-saving lamps. For example, when you press the switch, the light will light up for a while and then turn off automatically. This is because the electronic energy-saving lamp will generate a strong electromagnetic interference pulse when it is lit. If the interference signal is transmitted to the trigger end of CD4013 through some means, it will cause 4013 to flip again by mistake, causing the light to be turned off again.

In response to the situation, we developed a transient triggered flip-type four-relay anti-interference receiving board controlled by the AT89C2051 microcontroller, which can effectively solve the problem of control stability.

This receiving board is powered by a DC 9-12V power supply. You can directly plug a positive-inside and negative-outside voltage-stabilized power plug into a socket to supply power, or connect the power supply to the power terminals on the board.

Receiver board H Transient trigger flip type four relay receiver board: (receiver board 42 yuan each)

This is a four-way trigger flip-type receiver board designed and developed by us using the latest 2272 T4 chip. It can control four channels independently without affecting each other. The action logic is exactly the same as the receiver board G, but the hardware is greatly simplified. This receiver board is powered by a DC 9-12V power supply, and the power supply can be directly connected to the power terminal on the board.