Multifunctional remote control circuit diagram produced by NE555 and LM909

The circuit consists of two parts: generator and receiver. Transmitters include astable multivibrators (or duty cycle generators), tone generators and RF oscillators. The receiver mainly uses the integrated circuit LM909.

For the multivibrator composed of IC1 (555) and R1, R2, R3 and C3, the charging and discharging time constants can be changed by moving the switch K1 to different positions. When in the "1" position, the duty cycle D=(R2+R3)/(R1+R2+R3+R4)≈60%; when in the "2" position, D is 30%; when in the "3" position , D is 100% (that is, IC1 ③ pin outputs a low level signal). The output signal of IC1 is divided into two channels and added to the status switch circuit BG2 and BG3 after passing through D3. When K2 is in the "1" position, BG3 is saturated and conducts, and the output signal of IC1 is added to the control terminal of IC2, triggering it to generate 5.5kHz+ 600Hz square wave signal; when K2 is connected to the "2" position, BG2 and BG3 are cut off, IC2 only generates a single 5.5kHz pulse signal, and the two output states I1 and I2 of the corresponding receiver LM909 are both 0, and the motor does not Work; when K2 is connected to the "3" position, BG2 is saturated and conducts, triggering IC3 to generate a signal with an oscillation frequency of 5.5kHz-600Hz. The audio oscillation signal output by IC2 is added to the high-frequency oscillator BG1, which modulates the 27MHz high-frequency carrier wave, and then transmits it through the antenna TX.

In addition, the integrated circuit LM909 integrates radio frequency amplification, detection, audio decoding circuit with phase-locked loop, AGC circuit, level detection and drive circuit, etc. It receives and demodulates different modulated audio signals (5.5 kHz, 5.5kHz+600Hz, 5.5kHz-600Hz), so that the output I1 and I2 states of LM909 are different, thereby controlling the movement of the two motors M1 and M2 to achieve the purpose of remote control.

This circuit controls the two motors M1 and M2 of the receiver by controlling the switches K1 and K2 on the transmitter, thereby changing the motion state.