Since the LED is used as a lighting, there is an advantage of energy saving, long-lasting life, and now LED lighting is very hot. Due to the LED needs a low voltage DC power supply. In order to use 220V (or 110V) to exchange the city electric drive LED. A power conversion circuit is required. Ordinary common linear power supplies due to the shortcomings of large volume, low efficiency, is not suitable for use here, but commonly used switching power supplies require design transformers. The design and manufacturing process is more complicated and is not suitable for fan DIY.
The LED driver power circuit described below is very simple. And all the products that make it easy to purchase in the market are very suitable for enthusiasts. This power supply supports 90V ~ 265V exchange market power input. Output constant current 100mA. It is capable of driving 4 to 5 series LED modules.
Fig. 1 is a schematic diagram of the circuit of this production. The chip of the LNK304 of the switch tube is integrated interior. Circuit topology is buck-boost structure. 90V ~ 265V AC market is rectified by D4, and C5 filtering into people U1, and there is a reference source inside U1, and a 1.65V reference voltage will be generated between the FB feet and the S pin. This voltage and R12, R2, and R4 together determine the output current. The specific calculation formula is:
I = 1.65X (R2 + R1) / (R2XR4)
According to the value in the figure. The output current is around 100 mA.
The C4 in the figure is a chip filter capacitor, a burr on the C1 filtering R4. C2 is an output ocher capacitor. In order to prevent the output voltage is too high when the LED is not connected. D2 and D1 constitute a pressure pressure circuit. The output voltage is determined by the voltage regulation value of D1 at the time of no load.
Making can be done on the cave plate. Where R3 is an insurance resistance. You can also replace a fuse of about 250W1A. C3 and C10 are electrolytic capacitors, C4 and C2 are ceramic capacitors. In particular, C2 cannot use electrolytic capacitance, instead, otherwise it will be more severe. D2 and D5 require ultra-fast recovery diodes with a pressure about 500 V, which can be replaced with HER107, MUR160, and the like. L1 is inductively inductive with 10 mm in diameter.
The production completed circuit is shown in Figure 2 (omitted). After the production is completed, you can connect the light-emitting diode test. Five groups (4 to 5 series) can also be used in series with 4 ~ 5 power LEDs, and 4 to 5 series each) can be used in parallel, and the current is about 20 mA. Do not directly turn on 220V city electricity during testing. So as not to cause danger. You can adjust the adjustable DC voltage regulator power supply to around 30V, which is losed. In the entry, if the LED can emit light normally and the current is about 100 mA, it can be directly turned on. In the process of collecting market, pay special attention to safety because the entire circuit is not isolated. Touch to any part can cause electric shock.
Successful production, this can be used to make an LED table lamp. Figure 3 (omitted) gives pictures of actual work, lighting five 1W LEDs. Read more
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