High-Performance LED Driver / Power Supply Series. A reliable LED Driver is extremely crucial in order to provide an enhanced color rendering and extend the lifespan of LED light bulbs.
Power supply for LEDs with your own hands The electronic transformer is the cheapest switching power supply, but as you know, everything cheap is garbage. This law also operates here, but on the basis of electronic transformers it is possible to assemble a good power supply for powering powerful LEDs and LED modules. I will introduce the conversion cycle of the electronic transformer, and as a test I will use a Chinese electronic transformer for 12 volt halogen lamps with a power of 50 watts.
In fact, 50 watts is power consumption, and the net output power is not more than 25-30 watts, so it should be, since the efficiency of similar circuits does not exceed 60%. The scheme of itself is an ordinary half-bridge inverter, to strengthen the circuit, of course you can, but we will talk about it some other time. We will try to redesign the power supply and use LEDs with a power of 10 watts to power them. To begin with, we will need to rewind, or more accurately to fool a pulse transformer, since the optimum voltage for these LEDs is 11.5 Volts, and under load, the voltage of the PS drops to 7 Volts. In this power supply, the secondary winding consists of 9 turns of 0.8mm wire, we need to separate one of the secondary winding leads from the board. Then we look at the secondary winding and in the same direction we wind 4 turns of the same wire. You do not need to disassemble the transformer, you also do not need to wind the maximum smooth winding, everything will not increase the efficiency.
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After winding, you need to clean the varnish from the ends of the wire, then successively connect the new and factory winding. This is done so - the tip that was dropped from the board is attached to one of the ends of the new winding, but you need to observe the end of the windings (phasing), for example - the beginning of this winding to the end of the second or vice versa.
Thus, we get one whole winding, one of the ends of the wound winding (the free end that remains after the phasing of the windings) is sealed on the board in place of the old one. We get about 14 - 15 Volts without load at the output, with a load of the order of 10.5-11 Volts - what we need. Further, this tension needs to be straightened. In order not to torture ourselves, we use only one diode (you can use Schottky diodes from computer power supplies or any impulse diodes with a current of more than 3 Amps).
After the diode you need at least somehow to smooth out the ripple, for this you can use a film capacitor with a capacity of 0.22 - 1 μF. At the output, we get a rectified current, which needs to be stabilized, because at sudden jumps in the mains voltage, the unit can burn the LED due to a sharp increase in the output voltage. Stabilization can be realized in two ways - using an integral zener diode, or using a self-made linear regulator on a transistor. In the case of the first variant, you can use the ready-made microcircuit from the 7812 series - an integrated linear voltage regulator at 12 volts. The stabilizer must be fixed to the heat sink. The second option is more reliable, here is used a zener diode and a powerful power key, the transistor is also installed on the heat sink.