Why Can't CCTV Microphone Use the Switching Power Supply

  • source: sizheng;
  • Time: 2019-06-24

Generally, during the use of the CCTV microphone, we recommend that users use a 12V DC power supply and avoid using a switching power supply.


So why not use a switching power supply? We will tell you how to use the switching power supply from the working principle of the CCTV microphone and the working principle of the switching power supply.


switching power supply

The CCTV mic is a highly sensitive sound collection device. It has a built-in amplifier circuit that allows direct active speakers.


The working model of the switching power supply: As the name implies, the switching power supply uses electronic switching devices (such as transistors, FETs, thyristors, etc.), switching power supplies and circuit diagrams to control electricity, enables the electronic switching device to be "on" and "off" continuously, allowing the electronic switching device to pulse modulate the input voltage, thereby achieving DC/AC, DC/DC voltage conversion, and adjustable output voltage dynamic regulation. Compared with a linear power supply, the switching power supply is more effectively operated by "chopper", which is to convert the input DC voltage into a pulse voltage having an amplitude equal to the input voltage amplitude.


The duty cycle of the pulse is regulated by the controller of the switching power supply. Once the input voltage is clamped into an AC square wave, its amplitude can be raised or lowered by the transformer. By increasing the secondary winding of the transformer, the number of groups can increase the voltage value of the output. Finally, these AC waveforms are rectified and filtered to obtain a DC output voltage.


The main purpose of the controller is to keep the output voltage stable, and it's working operation is very similar to that of a linear controller. That is to say, the function block, voltage reference and error amplifier of the controller can be set the same as the linear regulator. The difference is that the output of the error amplifier (error voltage) goes through a voltage/pulse width conversion unit before driving the power tube.


Switching power supplies have two main modes of operation: forward conversion and boost conversion. Although the layout of their parts is very small, the working process varies greatly, in specific applications, each has its merits.

Because it is an "open" and "off" way to turn the exchange point into a DC point. Therefore, more interference is generated compared to the linear power supply. These disturbances are placed in monitoring products like cameras very subtle, but placed inside the CCTV microphone is completely different (because the pickup has built-in amplifier circuit). So many times we can hear very strong currents that interfere with the sound. So we often recommend when installing the CCTV microphone, the user does not need to share the power with the camera. Try to supply power independently and do not use the switching power supply.


During the use of the power supply, many users also asked how to distinguish between the switching power supply and linear power supply. In fact, most of the domestic security markets are not marked, but also difficult to distinguish in appearance (they are works differently) so it is best to ask the seller. Under normal circumstances, the business will not hide. But also because of their different working principles, switching power supplies use more chips than ordinary linear power supplies, it saves a lot, so it is also a 50W power supply. The switching power supply is much smaller and cheaper than a normal linear power supply. Sizheng Technology advises users here if you want to save trouble, recommend using a positive dedicated power supply or normal power supply.



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