Schematic diagram of FM stereo encoder with discrete components

Schematic diagram of FM stereo encoder with discrete components

Xiaoxiao recently discovered a previous experiment from old data. At that time, Xiaoxiao didn't have a 38KHZ crystal. Later, I found this picture from a friend. If you are interested, you may wish to try it.

Circuit schematic diagram Y1 and Y2 in IC1-4069 form an oscillator with a frequency of 76KHZ. After Y3-Y6 isolation and shaping, it is sent to a two-component frequency circuit composed of IC2 double JK flip-flop CD4027 to produce a symmetrical +/-38KHZ And 19KHZ square wave, of which +/-38KHZ square wave is used to control IC3 analog switch CD4066, switch and modulate the input stereo audio signal, mix it with 19KHZ frequency signal, and then isolate it by transistor 9014 and send it to FM modulator . For the FM modulator circuit, please refer to the various FM transmitter circuits in this site. This article is not drawn, the purpose is to make it easy for enthusiasts to use this encoder, not only can add stereo function to your previous FM transmitter, but also as a general equipment.

Commissioning Connect the FM modulator and the five-volt power supply as shown in the figure. Use a multimeter to measure the pins of IC1CD4069 and the pins of IC2 CP, Q, Q and IC2. The voltage should be half of the power supply voltage, indicating that the oscillator has started oscillating. If there is a digital cymometer, measure the output frequency of IC1 and adjust RW1 to make the frequency 75KHZ+/-10HZ. If not, you can adjust the radio first. After RW2 is adjusted halfway, adjust RW1 to make the radio stereo indicator light and there is no temple-frequency whistling sound in the speaker. Then send a stereo audio signal (1.5Vpp, can be output by a power amplifier)from the input, and then you can receive the stereo broadcast on the radio. The input signal can also be obtained from the circuit, but at this time R7 should be changed accordingly. Finally, you can adjust R7 to minimize the high-frequency noise. In fact, R6 and R7 are equivalent to the external components in the 13 and 14 pins of BA1404. They are the pilot signal and composite signal mixing circuit, and then input into the amplifier. It is 9014, and BA1404 is entered from 12 feet. I think this circuit has many areas to be improved. If you are interested, you might as well develop it.

Encoder|Transmitter|Soft starter|Power supply|VFD|Light curtain|Servo products|Human-machine interface|Solenoid valve|Cylinder|Actuator|Flow meter|Transformer|Thyristor|Sensor|Deceleration drive gearbox reducer|Linear guide|Circuit breaker|Refrigeration compressorAll industrial products of okplazas are purchased from the original factory or formal channels of agents to ensure the original authenticity, which perfectly solves the problem of industrial product sample procurement and small-batch procurement for the majority of engineers and purchasing personnel.

4066 internal block diagram:

Encoder|Transmitter|Soft starter|Power supply|VFD|Light curtain|Servo products|Human-machine interface|Solenoid valve|Cylinder|Actuator|Flow meter|Transformer|Thyristor|Sensor|Deceleration drive gearbox reducer|Linear guide|Circuit breaker|Refrigeration compressorAll industrial products of okplazas are purchased from the original factory or formal channels of agents to ensure the original authenticity, which perfectly solves the problem of industrial product sample procurement and small-batch procurement for the majority of engineers and purchasing personnel.

4069 internal block diagram:

Encoder|Transmitter|Soft starter|Power supply|VFD|Light curtain|Servo products|Human-machine interface|Solenoid valve|Cylinder|Actuator|Flow meter|Transformer|Thyristor|Sensor|Deceleration drive gearbox reducer|Linear guide|Circuit breaker|Refrigeration compressorAll industrial products of okplazas are purchased from the original factory or formal channels of agents to ensure the original authenticity, which perfectly solves the problem of industrial product sample procurement and small-batch procurement for the majority of engineers and purchasing personnel.

4027 internal block diagram:

Encoder|Transmitter|Soft starter|Power supply|VFD|Light curtain|Servo products|Human-machine interface|Solenoid valve|Cylinder|Actuator|Flow meter|Transformer|Thyristor|Sensor|Deceleration drive gearbox reducer|Linear guide|Circuit breaker|Refrigeration compressorAll industrial products of okplazas are purchased from the original factory or formal channels of agents to ensure the original authenticity, which perfectly solves the problem of industrial product sample procurement and small-batch procurement for the majority of engineers and purchasing personnel.