Modification of regulated power supply with computer switching power supply
Why do you want to use a computer switching power supply to convert a regulated power supply?
First, it is cheap and easy to get. A used 200-watt computer switching power supply is about 30 dollars.
Second, the output current is large, the output of 4, 5 amps no problem, the general linear regulated power supply when the output current is slightly larger when the heat is very obvious, heat dissipation has become a thorny problem, and the advantage of switching power supply is high efficiency, less heat. Especially for battery chargers, car receivers power supply is very suitable.
Third, the ripple is small, can meet the general use requirements.
Fourth, and the same power linear regulated power supply than, light weight, small size.
There are also shortcomings:
First, the stability of the output voltage is not as good as linear regulated power supply.
Second, there is a certain electromagnetic radiation interference.
Third, the output voltage is not easy to do from 0 volts.
Computer switching power supply modification of regulated power supply method?
Computer power supply circuits are varied, it is not convenient to repeat. Introduce the idea of modification.
First, remove the original rectifier filter and feedback loop.
Second, according to the output voltage and current redesign rectifier filter circuit. Special attention to the use of Schottky diodes, and fixed in the original installation of diodes on the heat sink, plus insulating gaskets.
Third, in the filter capacitor and a suitable drain resistor at both ends, pay attention to the resistance value and power.
Fourth, according to the secondary winding of the original transformer to select a few pins for the tap, tap how many and voltage according to the output voltage to determine. This is a job that requires skill.
Fifth, redesign the feedback loop, so that the output voltage can be adjusted with a variable resistor. This may require access to the pin function of the relevant integrated circuits.
Several issues should be noted:
First, disassemble the transformer to rewind the coil can also be. It is not easy to control the inductance under amateur conditions. Winding a single-ended flyback transformer is more difficult. However, the half-wave conversion circuit is not strict on inductance. It is better to wind the primary section.
Second, if designed as a multiple output, only one set of output voltage can be more safely controlled.
Third, the circuit to regulate the output voltage is designed as follows: if the variable resistor contact is open, the output voltage is * low. Prevent poor contact with the variable resistor contacts and make the output voltage increase instantly.
Third, pay attention to personal safety.
4, I use a 200-watt computer switching power supply successfully produced an output voltage of 3 volts - 35 volts output current of 5 amps regulated power supply.
