The main components required for linear power supply design include:
Linear power supply characteristics
Linear power supplies typically convert the AC voltage of various electronic devices into lower DC voltage. The AC mains voltage is usually 120V@60Hz or 220V@50Hz Then, it is converted to the required DC level voltage through a linear power supply. Linear power supply modules can provide fixed arbitrary DC voltage or various voltages (+5,+12, -12 V) for larger circuits. They can also create bipolar voltages, such as ± 15V for operational amplifiers or dual tracking power supplies with mutually locked voltages. The common uses of linear power sources are communication systems, amplifiers, laboratory testing equipment, various control circuits, and high-power industrial equipment. Examples of linear power output voltage include:
Connect to the main power supply through switches, fuses, or indicator lights. Ensure good grounding and insulation of any exposed wires with sleeves to protect the power supply.
A transformer with turns and structure based on the required output voltage. This is used to isolate the remaining parts of the downstream circuit from power reference. Transformers may have multiple taps to allow different power input voltages and secondary taps to obtain the required output voltage. Some transformers may have a copper foil shield between the primary and secondary taps to reduce capacitance coupling to high-frequency power source noise.
A rectifier that converts AC signals into DC. Generally speaking, a full wave bridge rectifier is the most suitable. However, please ensure that the diode you choose has been carefully calculated. The use of inexpensive or small diodes may lead to faults caused by excessive current or overvoltage spikes. Choosing diodes with peak reverse voltage may also be helpful in addition to using longer leads for better heat dissipation. Small capacitors can also be placed in parallel for faster recovery.
Smooth capacitors are used to reduce the amount of AC ripple on the output quasi DC voltage of the rectifier. Capacitors with low equivalent series resistance (ESR), such as tantalum based capacitors, can better handle ripple.
A voltage regulator is used to reduce voltage and provide a constant DC voltage to the load. It can be a series connection, shunt, simple or complex regulator. This component is complex and will be further discussed in the following sections.
