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LM567 Universal tone decoder integrated circuit applications

Published on Mar 11 2011 // Device application circuits

567 for the general tone decoder, when the input signal in the pass band to provide saturated transistor switch to ground, the circuit from the I and Q detector structure, driven by a voltage controlled oscillator center frequency of the oscillator to determine the decoder. Independent set with an external component output center frequency bandwidth and latency.
Mainly used for oscillation, modulation, demodulation, and remote control code, decoding circuitry. Such as power line carrier communications, radio sub-audio decoder, remote control and so on.

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With an external resistor the frequency range of 20 to 1
Logic compatible output with 100mA current absorption capacity of absorption.
Adjustable bandwidth from 0-14%
Width of the high signal output and noise suppression
Interference of false signals
High stability of the center frequency
Center frequency adjustment from 0.01Hz to 500kHz
Power supply voltage 5V – 15V, recommended 8V.
Example: 104 capacitor input termination, output termination pull-up resistor 10K, C1, C2 to 1uF. R1, C1 determine the oscillation frequency, generally 104 capacitor C1, R1 is 10K – 200K. Supply voltage of 8V.
Single-channel infrared remote control circuit
Control without the need for multiple applications, you can use the integrated circuits formed by conventional single-channel infrared remote control circuit. The control circuit does not require a special codec to use more expensive and therefore lower costs.
Single-channel infrared remote control transmitter circuit shown in Figure 1. Launch a high-speed circuits using CMOS-based quadruple two input "and not" gate 74HC00. The "non" gate composed of the carrier 3,4-oscillator, the oscillation frequency f0 in the 38kHz tone about; "and not" low-frequency oscillator composed of 1,2-door, do not have to fine-tune the oscillation frequency f1. modulation of f0 f1, so from the "non" gate 4 outputs the carrier waveform is intermittent, which is transmitted by infrared light-emitting diode waveform. Several key points of the waveform shown in Figure 2, Figure B ‘A point waveform is modulated waveform without direct access to high point when the B output waveform. It can be seen from Figure 2, when the A point of the waveform is high, the infrared light-emitting diode carrier launch; A point when the waveform is low, does not emit infrared light-emitting diode carrier. The frequency of this stop is to first serve low-frequency oscillator frequency f1. Why in the infrared emission circuit is not used inexpensive low-speed CMOS quad two input "and not" gate CD4011, and the use of higher-priced 74HC00 it? Mainly due to power supply voltage. IR emitter shell are varied, but the power is generally designed to 3V, with two 5 or 7 batteries for power. Although the nominal operating voltage of CD4011 3 ~ 18V, but it is in terms of dealing with digital signals. Because this CMOS "and not" the door is used as a square wave oscillation signal, ie analog applications, so it’s working voltage at least 4.5V for the job or not easy to vibration, impact of use. The 74HC series CMOS digital integrated circuits minimum operating voltage of 2V, 3V power so use it "handy" the. 74HC00 pin functions shown in Figure 3.

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Figure 4 shows the infrared receiver demodulation control circuit. The figure, IC1 is the LM567. LM567 is a PLL circuit, 8-pin plastic dual in-line. The 5, 6 pin external resistor and capacitor determine the center frequency of the internal VCO f2, f2 ≈ 1/1.1RC. The 1, 2 feet were usually grounded through a capacitor to form the output filter network and loop single-stage low pass filter. 2 pin capacitance of the connection the capture bandwidth of the PLL: the greater the capacitance, the narrower the loop bandwidth. 1 feet have connected capacitor pin capacitor should be at least 2 times 2. 3 pin is input, requiring the input signal ≥ 25mV. 8 pin is a logical output, and its interior is an open collector transistor, allowing maximum sink current of 100mA. LM567 operating voltage of 4.75 ~ 9V, the operating frequency from DC to 500kHz, quiescent current of about 8mA. LM567’s internal circuitry and the process is very complex and detailed work, here only its basic functions are summarized as follows: When the LM567’s 3 pin input amplitude ≥ 25mV, frequency of the signal bandwidth, 8 feet from the high into low , 2 pin output by the frequency / voltage conversion of the modulated signal; 2 If the device pin input audio signal output pin in5,2 pin input modulated signal by modulating the FM square wave signal. The circuit in Figure 4, only the use of the LM567, we receive the same frequency carrier signal 8 pin voltage from high to low this feature to control the formation of the control object.

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LM567 clarified the basic working principle and function, again the circuit of Figure 4 would be very simple. IC1 is the infrared receiver that receives infrared signals emitted by transmitter, the transmitter center frequency and the same carrier frequency f0, demodulated by IC1, the output OUT output frequency f1 of the square wave signal, which is shown in Figure 1 A point in the same signal waveform. We will be transferred to the center frequency of LM567 and transmitter "and not" the same oscillation frequency of 1,2-door, even if f2 = f1. When the transmitter is transmitting signals, LM567 began to work, 8 feet from high level to low level of use of this change can be to control a variety of objects. The circuit in Figure 4, we can make remote control switch, remote control of various home appliances.
In fact, the use of Figure 1 and Figure 4 shows the circuit, we can more easily be transformed into multi-channel remote control circuit. Is: in the transmitter (Figure 1) will stop resistance R * into a different number of values, the resulting frequency of several different modulation signal; in the receiving circuit, set the number of only the LM567, the input comes from IR receiver, the oscillation frequency of each LM567 different but one correspondence with the transmitter. So that when a different transmitter button press, access to different modulation signal corresponding to the LM567 at the receiving end of 8 foot level will change, thus forming multiple control. Strictly speaking, this is a form of frequency division multiplexing, and digital encoding and decoding multi-channel control than the disadvantage is that debugging is more complex. However, in some cases, such as multiple alarms, also has its place. Applications due to the alarm, the need to address two issues alarm over the same time, using time division multiplexing with complex synchronization problems in case of bandwidth to allow frequency division multiplexing using is very easy to solve.
Ultrasonic remote control circuit
1, ultrasonic remote control light switch
The remote control switches, circuit is simple, and free testing, is suitable for beginners production.
First, the working principle
For the transmitter. Circuit using discrete devices pose, VT1 and VT2 and R1 ~ R4, C1, C2 constitute a self-excited multivibrator, ultrasonic B transmitting device is connected in the collector loop VT1 and VT2 in the form of work to push-pull, loop time constant by the R1, C1 and R4, C2 determined. B ultrasound emitter resonant frequency of the multivibrator circuit triggered. Therefore, the circuit can work in the best frequency.

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(Figure 2) for the receive circuit, junction field effect VT1 constitute a high input impedance amplifier, and ultrasound can well match the receiving device B, available to selected high receiver sensitivity and frequency characteristics. VT1 by self-bias way to change the attitude of R3 to change the operating point of VT1, ultrasonic receiving device will receive the ultrasonic B converted to the corresponding electrical signals, amplified by the VT1 and VT2 poles, and then carried out by the half-wave VD1 and VD2 rectifier into a DC signal, the post integral role of C3 and the base in VT3, the VT3 into conduction by the deadline, the collector output negative pulse triggered JK flip-flop D, its flip. JK flip-flop Q terminal level direct drive relay K, the K pull or release. K by the relay switch control circuit contacts.
Second, component selection
Transmitter circuit, VT1 and VT2 with CS9013 or CS9014 and other small power transistors, ≥ 100. Ultrasonic emission devices using SE05-40T, using a 9V power supply GB laminated batteries, to reduce the size and weight of the transmitter.
Receiver circuit, VT1 and 3DJ6 3DJ7 or other small power junction field effect transistors. VT2 ~ VT3 with the CS9013, ≥ 100. VD1 and VD2 with the IN4148. JK flip-flop 263B. Ultrasonic receiving device using SE05-40R, paired with the SE05-40T. Relay K-type with the HG4310.
Ultrasonic remote control fan gear
First, the working principle
(Figure 3) transmitter. It uses a homemade bat brand FS-A5A-type electric fan remote control transmitter. The transmitter features small size, low power consumption, reliable, and simple circuits. In use, each click launch button, the transmitter sent the 40KHZ Ultrasonic about 500ms. Transmitter circuit works as follows.

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VT2 and VT3 a direct coupled positive feedback oscillation circuit, B is 40KHz ultrasonic emission devices, and the feedback oscillator circuit and the first frequency components. Therefore, this circuit can oscillate at exactly the center frequency of ultrasonic emission devices 40KHZ. VT1 and R2, C1 500ms delay circuit components. R1, VD1 is the discharge channel C1, the time when you press the launch key S, VT2 oscillation circuit constituted, issued ultrasound, the same time, the power charge through R2 to C1, when the C1 on the potential charge to 1.4V (approximately 500ms after ), VT1 conduction, VT2 and VT3 collector potential base dropped to about 0.3V, the oscillator stops, when the release when firing key S, C1 discharges rapidly through the VD1 and R1, to prepare for the next launch. VD3 and R4 constitute a firing instruction circuit, when the press launch key, VD3 light.
(Figure 4) for the receiver circuit. CMOS NAND gate D1 ~ D3 R1 offset by a linear amplifier, total gain of up to 60bB above, due to high input impedance CMOS circuit, it can be a good match with the ultrasonic receiving device. Amplified signal from the C1 decoder coupled to the PLL input of LM567 3 feet. When the input signal frequency falls when its center frequency, LM567 8-pin logic output from the high to low.

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Voice Switching Frequency Selection
This voice-activated switch can be a particular pitch (500 to 2000Hz) to control the sound of any electrical appliances on or off. Because it has a certain frequency selection effect, it is a small chance of malfunction.
Circuit design for the use of audio signals (up to 100mV) to control, the control signal source can be a telephone, radio, record player, tape recorder, the appropriate point from which lines drawn with a shield. If you want to use acoustic remote control, plus an electret microphone and a preamplifier can be.
The circuit of the device shown in Figure 16. It is the center of the pickup device is a piece of integrated circuit LM567, and a 50mA relay.
A certain tone to the LM567 audio signal is applied to the input of (3 feet), after amplification in the circuit, selected frequency and other treatment, in its 8-pin output low output (no input signal is high.) At this time, instead of connecting tube, a PNP (2N3906) turns on, the collector circuit connected to the relay, which could in its electrical contacts to control the accused. If used to start, use the relay normally open contacts move together; if used to shut down, should be used often together, moving the open contacts.
Frequency response depends on the connected pin 5,6 potentiometers and capacitor values, so adjust the 10kΩ potentiometer to adjust its frequency response. The machine can receive the audio range of 500 ~ 2000Hz.
1N4001 diode to protect transistor. 2N3906 can use any other type of medium and small-power PNP silicon tube instead.

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Infrared photodetector in electrostatic spray application of target
Abstract: Details of the infrared detector, and using infrared photoelectric detector position of cotton, to achieve the target spray design.
Agriculture is the foundation of national economy, advanced harvest plant protection technology is the protection of agricultural production, the modern plant pest control is still dominated by chemical control, pesticide application of conventional application methods and equipment behind, a large number of pesticide loss to water, soil and atmosphere in low utilization of pesticides, control costs are high, and caused serious environmental pollution, poor results for some pest control, advanced application methods and pesticide application equipment research and development of the sustainable development of agriculture in China to reduce production costs, especially important role in protecting the environment. Spray on the target is a newly developed high efficiency and low pesticide application of new technologies, AGTECH company developed the "Tree-sense" smart sprayer with the "Desert Storm" to detect enemy tanks using three-dimensional image sensor, it can under the crop distance, the shape of the effective spray; DURAND WAYLAND company’s "Smart Spray" spray, "Tree-see" sprayer uses advanced sonar systems for accurate target positioning accuracy of these devices, but expensive. According to our country, we designed an infrared photodetectors for target detection, combined with the high-voltage electrostatic droplet charged, charged droplets as a directional movement toward the plant, and finally adsorbed on the plants, the hit rate increased significantly. The development of infrared detectors, low cost, high sensitivity, small size, coupled with the electrostatic binding, these systems will achieve the same effect.
Design ideas
This paper describes the development of infrared photodetectors. Infrared is a non-visible light, using special infrared tubes and receiving tubes, can effectively prevent the interference of the surrounding visible light, the non-contact detection, does not damage the measured object. The detector is installed in the small electric car. Infrared target spray is mainly used in cotton and growth during the seedling stage, when the cotton in the seedling stage, the seedling dispersion, on target easily. When the growing season, the cotton stems have a certain altitude, then stems infrared radiation through reflection, identifying the target. Attaches great importance to take into account the farmers field management, very few weeds in cotton field, so the interference infrared photodetector by a very small and can be ignored.

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Figure 1 Schematic infrared detector frame

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Figure 2 Detection Range

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State diagram Figure 3 555

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Figure 4 Infrared devices transmit and receive direction

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Design of infrared photodetectors

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Shown in Figure 1, LM567 decoder integrated PLL lock circuit components and its peripheral components. Transistor V1, H1 infrared emission control and resistance R1, R9 form infrared transmitter circuit, PLL circuit oscillation signal output from the LM567’s 5 feet, sent to the V1 magnification, driving issue square wave infrared emission control signal. IC mA741, H2 and the infrared receiver infrared receiver circuit composed of external components, the infrared receiving tube H2 will receive the infrared signal into a change in their resistance, the resistor R3, capacitor C3 coupled to mA741 the 2 feet from mA741 zoom, 555 circuits, transistors V2 and its peripheral components related to the device output delay circuit, used to control the solenoid valve open time, when the cotton when detected, LED green light, power relay, normally open contacts closed, began to spray .
Infrared photoelectric detector to detect the infrared reflection of cotton is done by, in setting the effective detection range, without cotton, not reflected infrared receiver infrared receiver control signals, LM567’s output 8 feet high, 555 3 pin output low, transistor V2 cut-off, the solenoid valve does not close the spray; when detected in cotton, the infrared receiver tube receives Pi Mianhua infrared signals reflected back by the conversion circuit conversion, sent to the amplifier circuit μA741 zoom, The amplified signal is sent to the LM567’s 3 feet compared with the oscillation signal itself, when the oscillation signal with itself, with the frequency, LM567’s 8 pin output low, output 555 of 3 feet high, transistor V2 turn, relay power , began to spray solenoid valve to open.
In order to prevent malfunction produce interlaced detection, can be detected by adjusting the effective distance L (L2 in order to ensure the nozzle opening time, from 555, R7, C9 form a single state delay circuit shown in Figure 1. V2 of the output pulse width Tp0 = R7 · C9 · ln3 ≈ 1.1R7 · C9. If the circuit is stable for the duration of temporary interference trigger pulse, the pulse does not work, as shown in Figure 3, which guarantees the solenoid valve open time. Tp0 output pulse width can be R7 regulation.
Infrared transmitter and receiver in the radiating element to take into account the existence of the receiver components are directional. Therefore there is a position in this position sensors for maximum sensitivity. In addition, there is a sensor working range, as shown in Figure 4.
Using LM567 5 foot infrared LED drive pulse signal, in addition to the decoder using LM567 PLL improve the detection sensitivity and the elimination of background light such as sun interference, but also of the infrared LED in the average case of constant input power than the DC drive to double the transmission power. In the infrared detector infrared filter can remove the front plus visible light, infrared light through to further enhance the anti-jamming capability.
The biggest characteristic of the circuit is to achieve an infrared transmitter and receiver synchronization frequency automatic tracking, infrared emission part is no specific pulse circuit, and directly from the introduction portion of the pulse detection circuit (solid phase-locked center frequency for the LM567 signal), both to simplify the circuit and debugging work, but also prevent the environment changes and changes in device parameters caused by the sending and receiving frequency of inconsistencies, so that the circuit greatly enhanced stability and anti-jamming capability. The detector in the experiment has achieved good results, compared with non-target spray on spray greatly increased the hit rate.

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