Cars are charged with high and high-quality sound. I think the most important part of these systems is auto amplifier. With the ebilir switch mode “method, we can obtain the desired voltage from the car’s 12volt battery. The heart of the circuit that operates with the switch mode method is the SG3525 integration. The second important part in this circuit are the coils we will wrap.
The circuit employs two coils: TR1, which handles high voltage, and TR2, utilized to suppress generated frequencies. Both coils are wound around a standard 4cm diameter core using 1mm enameled wire. TR1 comprises primary and secondary windings, with the secondary output being derived from the circuit by providing a frequency input.
For TR1, the primary winding consists of 2 x 4 turns, while the secondary winding is 2 x 13 turns for a 2 x 35-volt output and 2 x 17 turns for a 2 x 42-volt output. TR2 is wound with 2 x 30 turns. It’s essential to observe the winding directions when creating these coils. A 2 x 35-volt output is suitable for the TDA7294 amplifier integration, or the voltage can be adjusted to meet the requirements of other noise-amplified amplifiers.
Voltage is crucial, but current is equally important for delivering power. To drive TR1 in the circuit, BUZ11 is used, and the number of MOSFETs employed depends on the power requirements. For instance, when I constructed a setup with 4 TDA7294 amplifiers, I used 2 x 4 pieces of BUZ11 MOSFETs to deliver 4 x 100W. In my tests, I was able to achieve powerful and clear sound without additional cooling, but higher volumes necessitate effective cooling.
As the voltage from TR1 in the switch mode power supply is frequency-loaded AC voltage, standard diodes are not used for rectification. Ultra-fast diodes, such as the BYW29 diode, are recommended. It’s important to insulate all MOSFETs and diodes when mounting them onto the cooler.
The circuit features a voltage control section facilitated by opto-coupler components. Furthermore, the output voltage can be fine-tuned using the trimpot within the circuit.
The SG3525 includes a shut-down SG output. The circuit remains in the shut-down state until it receives a +12V input. Hence, a +12V input is required in this part of the circuit.
The car auto amplifier is controlled by the car stereo’s remote bin output. When the car stereo is powered on, it sends a signal to the car amplifier, turning the amplifier on. To achieve this, a simple transistor circuit has been incorporated into the circuit. Below, you can find the circuit’s schematic diagram.