In a distinct configuration, the control system for a PC power supply employs transformers along with the SG3525 controller and IRF730 primary drive transistors. However, it’s necessary to wind the transformer manually since the original power supply unit’s driver transformer voltage isn’t sufficient for certain requirements.
For a 250-watt Switched-Mode Power Supply (SMPS), a remarkable project outcome is achieved through the use of MOSFETs as Power FETs, although the overall system needed a specific method that I’m not entirely familiar with for proper alignment. Normally, the output from the power transformer is rectified using two IRFZ44N diodes if they are deemed appropriate for the task.
Drive Transformer BJT type winding secondary transformers according to BJT type transistors.
If you have a strong powersupply, you can see how many volts the drive transformer has by canceling the primary part in your hand and simply arranging it to the control floor and drive transformer.
I’ve provided an example in the image, but please note that the material values within the construction can vary. Typically, the most cost-effective standard components are used. To verify compatibility, you can check the TL494 or standard datasheet file for the test. All components utilized in the project and comprehensive details can be found there, including scope measurements and transformer information, which will be helpful for fellow enthusiasts.
The TL494 device incorporates two error amplifiers, an adjustable oscillator, a dead-time control (DTC) comparator, a pulse-steering control flip-flop, a 5V regulator with 5% precision, and circuits for controlling the output.
The error amplifiers have a common-mode voltage range spanning from -0.3V to VCC – 2V. The dead-time control comparator includes a fixed offset that results in approximately 5% dead time. The on-chip oscillator can be either bypassed by connecting RT to the reference output and supplying a sawtooth input to CT or used to drive common circuits in synchronous multiple-rail power supplies.
- Complete Pulse Width Modulation Control Circuitry
- On−Chip Oscillator with Master or Slave Operation
- On−Chip Error Amplifiers
- On−Chip 5.0 V Reference
- Adjustable Deadtime Control
- Uncommitted Output Transistors Rated to 500 mA Source or Sink
- Output Control for Push−Pull or Single−Ended Operation
- Undervoltage Lockout
- NCV Prefix for Automotive and Other Applications Requiring Site and Control Changes
- Pb−Free Packages are Available*