Change the Zhongjiu receiver to 12V power supply

After the 9-channel receiver is changed to 12V power supply, it can be used for outdoor mobile or car viewing. Because the power consumption of some 9-channel receiver motherboards is more than twice that of ordinary receivers, the power conversion board must also be large enough. The circuit in this article uses TL494 and high-power MOS tube structure, and the output power can reach 10w. It has power consumption current limiting function, so it is not afraid of load short circuit.

T1 is a switching transformer, and the core specification is EE28. Since the channels on the current 9-pin are all of the same polarization, the right polarization voltage (14v) is omitted in this power supply. The primary wire diameter is 0.5mm, the +3.3V winding wire diameter in the secondary is 0.45mm, and the +18v winding wire diameter is 0.3mm. D2, D3, C4, C5, C6 and L1 can all use the corresponding components on the original receiver power supply board. The test connects 10Ω and 100Ω dummy loads to the +3.3v output terminal and the +18v output terminal respectively, and connects an adjustable DC power supply to the power input terminal. When the input power supply voltage changes between 8v and 15v, the output voltage should remain stable. J1 is a 4PIN plug with wires, which is connected to the power input socket of the motherboard.

Q4: Choose a 10A 100v MOS tube, such as 10N10, which does not require a heat sink. The K3638 removed from an old computer motherboard works very well.