Intelligent video monitoring signal acquisition circuit module circuit schematic

Photocoupler

The terminal controller is responsible for two main functions. First, it manages the integrated camera and pan/tilt mechanisms based on instructions from the main controller. Second, it captures and processes voice signals from the current classroom environment before uploading them. For the camera and pan/tilt control circuit, the system receives RS485 control commands through a MAX485 interface. These commands are then used to activate a relay group that controls the PTZ motor's zoom, rotation, and aperture adjustments. Additionally, the MC145027 chip decodes the MCU’s instructions. The MCU sends an address command first, followed by a data command. Only when the address matches the one set in the MC145027 does the chip accept the data command, allowing individual addressable control of each terminal. The matrix switcher circuit supports 32 channels of audio and video monitoring. To simplify design, installation, and future upgrades, the system divides the 32 channels into four sub-boards, each handling 8 channels. Each sub-board provides 8 outputs, enabling a 32-to-4 output configuration. This setup is shown in Figure 3, where relays J1–J8 manage switching, and J4078 ensures synchronized audio and video switching. J11 and J12 are jumper sockets used to set the sub-board address. When the address matches the main controller’s selection (A0, A1, A2), the 4099 IC activates, allowing the main controller to select any channel via cmd0–cmd2. For voice signal acquisition, the system uses a logarithmic amplification circuit to ensure clear capture across large areas (up to 50 m²). Ordinary microphones would not be effective over such distances, so this design improves clarity. The logarithmic amplifier, as shown in Figure 5, uses two stages of LM358 operational amplifiers to boost the signal effectively. Overall, the integration of sensing and electronic technologies results in a simple, cost-effective, and practical system. It enhances student awareness, monitors independent learning tools, prevents unnecessary damage, and increases equipment reliability.